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Organic compound and particle emissions of additive manufacturing with photopolymer resins and chemical outgassing of manufactured resin products
Abstract
Photopolymer resins are applied at an increasing rate in additive manufacturing (AM) industry as vat photopolymerization (VP) and material jetting (MJ) methods gain more popularity. The aim of this study was to measure volatile organic compound (VOC), carbonyl compound, ultrafine particle (UFP), and particulate matter (PM10) air concentrations emitted in 3D printer operations. Individual chemicals were identified when multiple photopolymer resin feedstocks were used in various VP and MJ printers. The size distributions of UFPs, and indoor air parameters were also monitored. Finally, the VOC outgassing of the cured resin materials was determined over 84 days. The data demonstrated that 3D printer operators were exposed to low concentrations of airborne exposure agents as follows: average concentrations of VOCs were between 41 and 87 µg/m³, UFP number levels ranged between 0.19 and 3.62 × 10³ number/cm³; however, no impact was detected on air parameters or PM10 concentrations. A majority of the UFPs existed in the 10–45 nm size range. The identified compounds included hazardous species included sensitizing acrylates and carcinogenic formaldehyde. The outgassed products included similar compounds that were encountered during the AM processes, and post-processing solvents. Products heated to 37°C emitted 1.4‒2.9-fold more VOCs than at room temperature. Total emissions were reduced by 84‒96% after 28 days roughly from 3000–14000 to 100–1000 µg/m²/hr. In conclusion, resin printer operators are exposed to low concentrations of hazardous emissions, which might result in adverse health outcomes during prolonged exposure. Manufactured resin products are suggested to be stored for 4 weeks after their production to reduce potential consumer VOC hazards.
... Previous studies of 3D printers have identified emissions of several hazardous VOCs, such as styrene [7,[22][23][24][25][26][27][28][29][30][31] methyl methacrylate [22,29,32,33] isopropanol [32], benzene [22][23][24]34], and toluene [22-24, 28, 30, 34]. Some of these VOCs have been linked to adverse health consequences after large exposure doses, including increased risk of some cancers [16][17][18][19][20][21]. ...
... Previous studies of 3D printers have identified emissions of several hazardous VOCs, such as styrene [7,[22][23][24][25][26][27][28][29][30][31] methyl methacrylate [22,29,32,33] isopropanol [32], benzene [22][23][24]34], and toluene [22-24, 28, 30, 34]. Some of these VOCs have been linked to adverse health consequences after large exposure doses, including increased risk of some cancers [16][17][18][19][20][21]. ...
... The laser scans the entire plane of the structure, focusing the light on the selected curing zone for each pass. Previous research by Väisänen et al. [32] identified and quantified a range of carbonyl compounds released during stereolithographic printing a Formlabs Form 2, resin 3D printer with clear and castable Formlabs wax resins. Dental resins were also examined. ...
Background
Three-dimensional (3D) printing is a technique by which materials are continually added in layers to form structures. The technique has grown in popularity over the past decade and affordable desktop 3D printers are now widely used in schools, universities, businesses, and hospitals.
Objective
Understanding the types of chemical emissions from these 3D printers and their potential health effects is essential to safely use this technology.
Methods
A scoping literature review on volatile organic compound (VOC) emissions from resin-bed and filament 3D printers has been conducted. Most of the published research has focused on emissions from filament 3D printers.
Results
VOC emissions from resin 3D printers have been reported mostly as carbonyl compounds or methacrylate monomers. Filament VOC emissions are more varied in composition reflecting the constituents in the filaments used in this printer. The published research reported that the airborne concentrations of specific VOCs from 3D desktop printers fell below the HSE British workplace exposure limits (WELs). This may suggest that VOC emissions from these printers do not present a risk to occupational health. However, caution is required in reaching this conclusion because most of these studies quantified specific VOC emissions using methods different to those required by workplace regulatory standards. Other exposure circumstances, such as the effect of total VOC emissions, need to be considered, particularly for vulnerable groups, including individuals with respiratory disease, the elderly, or young children. Variables that could increase exposure and risks to health include long print times, multiple 3D printers, and poor ventilation. Research on the VOC emissions from resin 3D printers is required using experimental emission chambers.
Impact
The research discussed in this review focused on VOC emissions from desktop 3D printers and the potential health impacts associated with exposure to these compounds. The review identifies circumstances when people may be exposed to 3D printer emissions for which no regulatory exposure limits apply. This circumstance is especially relevant to people working in small businesses and organisations and to vulnerable people, such as the young, elderly and those with pre-existing lung disease. Raising awareness of these potential health concerns from 3D printer emissions can help to inform actions to mitigate exposure, through policy and behavioural changes, as well as engineering control measures. To our knowledge, this is the first review discussing studies of VOC emission from resin and popular filament 3D printers, including exposure risks and health outcomes.
... Individual sample constituents were identified by comparing the mass spectral patterns and retention times of peaks in the samples to the mass spectral patterns and retention times of a standard curve (acetone, isopropyl alcohol, hexane, benzene, toluene, ethylbenzene, xylenes, and methyl acrylate, ethyl acrylate, ethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, allyl methacrylate, glycidyl methacrylate, and hydroxypropyl methacrylate). Compounds in the standard curve were selected based on ingredient lists from Safety Data Sheets (SDS), prior characterization of vat resins (author's unpublished data), and available literature [5,[12][13][14][15][16][23][24][25][26]. Additionally, tentatively identified compounds were qualitatively identified from the remaining chromatographic peaks based on the mass spectral matches with mass spectral library software (Wiley Registry 8th Edition/NIST 2008 Mass Spectral Library, Wiley-Blackwell, New York, NY, USA) and a manual review by the analyst. ...
... This observation was consistent with Zhang et al. who reported that sub-micron size particle concentrations released during SLA printing were similar to the background [34]. In a series of studies, Väisänen et al. used a CNC to monitor emissions from several different VP machines and resins during printing [15,16]. In their studies, average particle concentrations during the operation of SLA and DLP printers were approximately 1200 to 3600 #/cm 3 . ...
... Though particle emission rates differed on a group-level basis in that study, for the specific SLA and DLP printers used in the current study, particle number concentrations were not significantly different [23]. Väisänen et al. reported that maximum particle number concentrations measured using a CNC instrument while printing with SLA and DLP printers were approximately 4000 to 13,500 #/cm 3 [15,16]; however, VP particle concentrations tend to be lower than fused filament fabrication (FFF). As heat is used to melt the polymer, particle concentrations can reach a maximum of 2 × 10 5 -1 × 10 6 #/cm 3 [3]. ...
Vat photopolymerization (VP), a type of additive manufacturing process that cures resin to build objects, can emit potentially hazardous particles and gases. We evaluated two VP technologies, stereolithography (SLA) and digital light processing (DLP), in three separate environmental chambers to understand task-based impacts on indoor air quality. Airborne particles, total volatile organic compounds (TVOCs), and/or specific volatile organic compounds (VOCs) were monitored during each task to evaluate their exposure potential. Regardless of duration, all tasks released particles and organic gases, though concentrations varied between SLA and DLP processes and among tasks. Maximum particle concentrations reached 1200 #/cm3 and some aerosols contained potentially hazardous elements such as barium, chromium, and manganese. TVOC concentrations were highest for the isopropyl alcohol (IPA) rinsing, soaking, and drying post-processing tasks (up to 36.8 mg/m3), lowest for the resin pouring pre-printing, printing, and resin recovery post-printing tasks (up to 0.1 mg/m3), and intermediate for the curing post-processing task (up to 3 mg/m3). Individual VOCs included, among others, the potential occupational carcinogen acetaldehyde and the immune sensitizer 2-hydroxypropyl methacrylate (pouring, printing, recovery, and curing tasks). Careful consideration of all tasks is important for the development of strategies to minimize indoor air pollution and exposure potential from VP processes.
... No report of ventilation controls for BJ, VP, PBF, or DED machines was identified by the literature search. Väisänen et al. (2022) noted a LEV control for an MJ machine and 6 articles evaluated ventilation controls for ME-type FFF 3-D printers. Of these six articles, three evaluated LEV at or near to the extruder nozzle (Dunn et al. 2020;Kwon et al. 2017;Viitanen et al. 2021), one evaluated the efficacy of a room LEV system (Zontek, Scotto, and Hollenbeck 2021), one evaluated the efficacy of an air purifier equipped with different particulate and gas combination filters positioned near a printer , and one evaluated room GEV (Secondo et al. 2020). ...
... Of these six articles, three evaluated LEV at or near to the extruder nozzle (Dunn et al. 2020;Kwon et al. 2017;Viitanen et al. 2021), one evaluated the efficacy of a room LEV system (Zontek, Scotto, and Hollenbeck 2021), one evaluated the efficacy of an air purifier equipped with different particulate and gas combination filters positioned near a printer , and one evaluated room GEV (Secondo et al. 2020). Väisänen et al. (2022) measured particles, VOCs, and carbonyls emitted from an MJ printer. The printer had a built-in LEV duct, and samples were collected from the lab room air and from the printer exhaust ventilation duct (operating at 7 ACH) when using different resins. ...
Additive manufacturing (AM) refers to several types of processes that join materials to build objects, often layer-by-layer, from a computer-aided design file. Many AM processes release potentially hazardous particles and gases during printing and associated tasks. There is limited understanding of the efficacy of controls including elimination, substitution, administrative, and personal protective technologies to reduce or remove emissions, which is an impediment to implementation of risk mitigation strategies. The Medline, Embase, Environmental Science Collection, CINAHL, Scopus, and Web of Science databases and other resources were used to identify 42 articles that met the inclusion criteria for this review. Key findings were as follows: 1) engineering controls for material extrusion-type fused filament fabrication (FFF) 3-D printers and material jetting printers that included local exhaust ventilation generally exhibited higher efficacy to decrease particle and gas levels compared with isolation alone, and 2) engineering controls for particle emissions from FFF 3-D printers displayed higher efficacy for ultrafine particles compared with fine particles and in test chambers compared with real-world settings. Critical knowledge gaps identified included a need for data: 1) on efficacy of controls for all AM process types, 2) better understanding approaches to control particles over a range of sizes and gas-phase emissions, 3) obtained using a standardized collection approach to facilitate inter-comparison of study results, 4) approaches that go beyond the inhalation exposure pathway to include controls to minimize dermal exposures, and 5) to evaluate not just the engineering tier, but also the prevention-through-design and other tiers of the hierarchy of controls.
... The severity of these hazards varies between different AM techniques, operation parameters, and materials used (Roth et al., 2019;Stefaniak et al., 2021;Romanowski et al., 2023). Most of the studies have concentrated on MEX printers, especially desktop printers (Stephens et al., 2013;Viitanen et al., 2021;Dunn et al., 2020;Du Preez et al., 2018;Azimi et al., 2016;Wojtyła et al., 2020;Zhang et al., 2017;Stabile et al., 2017;Floyd et al., 2017;Mendes et al., 2017), but some studies on PBF (Graff et al., 2017;Kangas et al., 2023;Jensen, A.C.0., Harboe, H., Brostrøm, A., Jensen, K.A., Fonseca, A.S., 2020), directed energy deposition DED (Bau et al., 2020;Ding and Ng, 2021), binder jetting BJT (Kangas et al., 2023;Afshar-Mohajer et al., 2015) and VPP (Zisook et al., 2020;Väisänen et al., 2022;Väisänen et al., 2019) have been published as well. ...
... These additives range from dyes, photopolymer resins, organometallic compounds, carbon nanomaterials, nanometal oxides to micrometer-scale particles such as copper, bronze, steel, tungsten, gold, and aluminum nitride (Vance et al. 2017). Several engineered nanomaterials were infused into PC filaments, such as silicon dioxide nanoparticles, titanium nitride nanoparticles (Vidakis et al. 2021), titanium carbide nanopowder (Vaisanen et al. 2022;Vidakis, Petousis, Grammatikos, et al. 2022), aluminum nitride nanoparticles (Vidakis, Petousis, Mangelis, et al. 2022), and carbon nanotubes (Potter et al. 2021). ...
During fused filament fabrication (FFF) 3D printing with polycarbonate (PC) filament, a release of ultrafine particles (UFPs) and volatile organic compounds (VOCs) occurs. This study aimed to determine PC filament printing emission-induced toxicity in rats via whole-body inhalation exposure. Male Sprague Dawley rats were exposed to a single concentration (0.529 mg/m³, 40 nm mean diameter) of the 3D PC filament emissions in a time-course via whole body inhalation for 1, 4, 8, 15, and 30 days (4 hr/day, 4 days/week), and sacrificed 24 hr after the last exposure. Following exposures, rats were assessed for pulmonary and systemic responses. To determine pulmonary injury, total protein and lactate dehydrogenase (LDH) activity, surfactant proteins A and D, total as well as lavage fluid differential cells in bronchoalveolar lavage fluid (BALF) were examined, as well as histopathological analysis of lung and nasal passages was performed. To determine systemic injury, hematological differentials, and blood biomarkers of muscle, metabolic, renal, and hepatic functions were also measured. Results showed that inhalation exposure induced no marked pulmonary or systemic toxicity in rats. In conclusion, inhalation exposure of rats to a low concentration of PC filament emissions produced no significant pulmonary or systemic toxicity.
... Broekhuizen et al. suggested a nano reference value of 40,000 particles/cm 3 for nanoparticles with a density below 6 g/cm 3 (polymer particles have a density of 1-2 g/cm 3 ), which was exceeded in this study for all FDM and extrusion prints with no encapsulation or filter (23). Other techniques in this study, i.e., VP, PBF, and MJ, had concentrations below 20,000 particles/cm3 (PBF) or even below 5,000 particles/cm3 (VP and MJ), which is in agreement with other studies (24). ...
Additive manufacturing (AM), or 3D printing, is a growing industry involving a wide range of different techniques and materials. The potential toxicological effects of emissions produced in the process, involving both ultrafine particles and volatile organic compounds (VOCs), are unclear, and there are concerns regarding possible health implications among AM operators.
The objective of this study was to screen the presence of respiratory health effects among people working with liquid, powdered, or filament plastic materials in AM.
Methods
In total, 18 subjects working with different additive manufacturing techniques and production of filament with polymer feedstock and 20 controls participated in the study. Study subjects filled out a questionnaire and underwent blood and urine sampling, spirometry, impulse oscillometry (IOS), exhaled NO test (FeNO), and collection of particles in exhaled air (PEx), and the exposure was assessed. Analysis of exhaled particles included lung surfactant components such as surfactant protein A (SP-A) and phosphatidylcholines. SP-A and albumin were determined using ELISA. Using reversed-phase liquid chromatography and targeted mass spectrometry, the relative abundance of 15 species of phosphatidylcholine (PC) was determined in exhaled particles. The results were evaluated by univariate and multivariate statistical analyses (principal component analysis).
Results
Exposure and emission measurements in AM settings revealed a large variation in particle and VOC concentrations as well as the composition of VOCs, depending on the AM technique and feedstock. Levels of FeNO, IOS, and spirometry parameters were within clinical reference values for all AM operators. There was a difference in the relative abundance of saturated, notably dipalmitoylphosphatidylcholine (PC16:0_16:0), and unsaturated lung surfactant lipids in exhaled particles between controls and AM operators.
Conclusion
There were no statistically significant differences between AM operators and controls for the different health examinations, which may be due to the low number of participants. However, the observed difference in the PC lipid profile in exhaled particles indicates a possible impact of the exposure and could be used as possible early biomarkers of adverse effects in the airways.
... The emissions from these plastics were reported to produce adverse health effects in both aquatic and land species (Burgos-Aceves et al. 2022;Dmytriw 2020;Martín et al. 2018;Rubio, Marcos, and Hernandez 2020;Suhyun et al. 2019). Recently, the use of 3D printers has increased, and there are data demonstrating that 3D printers used in areas that are not properly ventilated might generate and release high concentrations of respirable particulate and volatile vapors that may also affect health (Chan et al. 2020, Yi et al. 2016Kim et al. 2015;Leso et al. 2021;Vaisanen et al. 2022). The exact characteristics of the exposure, and the physiological and biological effects of the exposure, are dependent upon the concentrations and types of PM and VOC released during the printing process (Farcas et al. 2019;MT et al. 2020). ...
With the growing adoption of additive manufacturing (AM) technology across various industries, concerns regarding the possible release of hazardous volatile organic compound (VOC) emissions have surfaced, particularly in VAT photopolymerization (VPP) processes. This study investigates VOC emissions in VPP AM by implementing machine learning (ML) and advanced digital twins to monitor, predict, and mitigate VOC release. An Industrial Internet of Things (IIoT) sensor network, integrated with an Anycubic Mono X 6 K 3D printer, captured data on critical parameters, including layer thickness, exposure time, and light intensity. Subsequent ML model analysis identified exposure time as a principal factor influencing VOC emissions. A Unity-based digital twin was developed to support proactive process optimization, offering real-time visualization and predictive analytics of emission trends. The system aligns with Industry 4.0 objectives, showing considerable potential to enhance operational efficiency and environmental sustainability in VPP AM. This integrated approach significantly advances environmentally responsible AM practices in industrial settings.
Three-dimensional (3D) printing of manufactured goods has increased in the last 10 years. The increased use of this technology has resulted in questions regarding the influence of inhaling emissions generated during printing. The goal of this study was to determine if inhalation of particulate and/or toxic chemicals generated during printing with polycarbonate (PC) plastic affected the neuroendocrine system. Male rats were exposed to 3D-printer emissions (592 µg particulate/m3 air) or filtered air for 4 h/day (d), 4 days/week and total exposures lengths were 1, 4, 8, 15 or 30 days. The effects of these exposures on hormone concentrations, and markers of function and/or injury in the olfactory bulb, hypothalamus and testes were measured after 1, 8 and 30 days exposure. Thirty days of exposure to 3D printer emissions resulted in reductions in thyroid stimulating hormone, follicle stimulating hormone and prolactin. These changes were accompanied by (1) elevation in markers of cell injury; (2) reductions in active mitochondria in the olfactory bulb, diminished gonadotropin releasing hormone cells and fibers as well as less tyrosine hydroxylase immunolabeled fibers in the arcuate nucleus; and (3) decrease in spermatogonium. Polycarbonate plastics may contain bisphenol A, and the effects of exposure to these 3D printer-generated emissions on neuroendocrine function are similar to those noted following exposure to bisphenol A.
Introduction
3D printing is increasingly present in research environments, and could pose health risks to users due to air pollution and particulate emissions. We evaluated the nanoparticulate emissions of two different 3D printers, utilizing either fused filament fabrication with polylactic acid, or stereolithography (SLA) with light curing resin.
Methods
Nanoparticulate emissions were evaluated in two different research environments, both by environmental measurements in the laboratory and by personal sampling.
Results
The SLA printer had higher nanoparticulate emissions, with an average concentration of 4,091 parts/cm³, versus 2,203 particles/cm³ for the fused filament fabrication printer. The collected particulate matter had variable morphology and elemental composition with a preponderance of carbon, sulfur and oxygen, the main byproducts.
Discussion
Our study implies that when considering the health risks of particulate emissions from 3D printing in research laboratories, attention should be given to the materials used and the type of 3D printer.
Material jetting and vat photopolymerization additive manufacturing (AM) processes use liquid resins to build objects. These resins can contain skin irritants and/or sensitizers but product safety data sheets (SDSs) might not declare all ingredients. We characterized elemental and organic skin irritants and sensitizers present in 39 commercial products; evaluated the influence of resin manufacturer, system, color, and AM process type on the presence of irritants and sensitizers; and compared product SDSs to results. Among all products, analyses identified 23 irritant elements, 54 irritant organic substances, 22 sensitizing elements, and 23 sensitizing organic substances; SDSs listed 3, 9, 4, and 6 of these ingredients, respectively. Per product, the number and total mass (an indicator of potential dermal loading) of ingredients varied: five to 17 irritant elements (8.32–4756.65 mg/kg), one to 17 irritant organics (3273 to 356,000 mg/kg), four to 17 sensitizing elements (8.27–4755.63 mg/kg), and one to seven sensitizing organics (15–382,170 mg/kg). Median numbers and concentrations of irritants and sensitizers were significantly influenced by resin system and AM process type. The presence of undeclared irritants and sensitizers in these resins supports the need for more complete information on product SDSs for comprehensive dermal risk assessments.
Biocomposites (BCs) can be used as substitutes for unsustainable polymers in 3D printing, but their safety demands additional investigation as biological fillers may produce altered emissions during thermal processing. Commercial filament extruders can be used to produce custom feedstocks, but they are another source for airborne contaminants and demand further research. These knowledge gaps are targeted in this study. Volatile organic compound (VOC), carbonyl compound, ultrafine particle (UFP), and fine (PM2.5) and coarse (PM10) particle air concentrations were measured in this study as a filament extruder and a 3D printer were operated under office environment using one PLA and four PLA-based BC feedstocks. Estimates of emission rates (ERs) for total VOCs (TVOC) and UFPs were also calculated. VOCs were analyzed with a GC-MS system, carbonyls were analyzed with an LC-MS/MS system, whereas real-time particle concentrations were monitored with continuously operating instruments. VOC concentrations were low throughout the experiment; TVOC ranged between 34-63 µg/m3 during filament extrusion and 41-56 µg/m3 during 3D printing, which represent calculated TVOC ERs of 2.6‒3.6 × 102 and 2.9‒3.6 × 102 µg/min. Corresponding cumulative carbonyls ranged between 60-91 and 190-253 µg/m3. Lactide and miscellaneous acids and alcohols were the dominant VOCs, while acetone, 2-butanone, and formaldehyde were the dominant carbonyls. Terpenes contributed for ca. 20-40% of TVOC during BC processing. The average UFP levels produced by the filament extruder were 0.85 × 102-1.05 × 103 #/cm3, while the 3D printer generated 6.05 × 102-2.09 × 103 #/cm3 particle levels. Corresponding particle ERs were 5.3 × 108-6.6 × 109 and 3.8 × 109-1.3 × 1010 #/min. PM2.5 and PM10 particles were produced in the following average quantities; PM2.5 levels ranged between 0.2-2.2 µg/m3, while PM10 levels were between 5-20 µg/m3 for all materials. The main difference between the pure PLA and BC feedstock emissions were terpenes, present during all BC extrusion processes. BCs are similar emission sources as pure plastics based on our findings, and a filament extruder produces contaminants at comparable or slightly lower levels in comparison to 3D printers.
Knowledge gaps remain regarding the cardiorespiratory impacts of ambient volatile organic compounds (VOCs) for the general population. This study identified contributing sources to ambient VOCs and estimated the short-term effects of VOC apportioned sources on daily emergency hospital admissions for cardiorespiratory diseases in Hong Kong from 2011 to 2014. We estimated VOC source contributions using fourteen organic chemicals by positive matrix factorization. Then, we examined the associations between the short-term exposure to VOC apportioned sources and emergency hospital admissions for cause-specific cardiorespiratory diseases using generalized additive models with polynomial distributed lag models while controlling for meteorological and co-pollutant confounders. We identified six VOC sources: gasoline emissions, liquefied petroleum gas (LPG) usage, aged VOCs, architectural paints, household products, and biogenic emissions. We found that increased emergency hospital admissions for chronic obstructive pulmonary disease were positively linked to ambient VOCs from gasoline emissions (excess risk (ER%): 2.1%; 95% CI: 0.9% to 3.4%), architectural paints (ER%: 1.5%; 95% CI: 0.2% to 2.9%), and household products (ER%: 1.5%; 95% CI: 0.2% to 2.8%), but negatively associated with biogenic VOCs (ER%: −6.6%; 95% CI: −10.4% to −2.5%). Increased congestive heart failure admissions were positively related to VOCs from architectural paints and household products in cold seasons. This study suggested that source-specific VOCs might trigger the exacerbation of cardiorespiratory diseases.
Human health is closely related to his environment. The influence of exposure to air pollutants on human health and well-being has been an interesting subject and gained much volume of research over the last 50 years. In general, polluted air is considered one of the major factors leading to many diseases such as cardiovascular and respiratory disease and lung cancer for the people. Besides, air pollution adversely affects the animals and deteriorates the plant environment. The overarching objective of this review is to explore the previous researches regarding the causes and sources of air pollution, how to control it and its detrimental effects on human health. The definition of air pollution and its sources were introduced extensively. Major air pollutants and their noxious effects were detailed. Detrimental impacts of air pollution on human health and well-being were also presented.
Ultrafine particles (PM0.1), which are present in the air in large numbers, pose a health risk. They generally enter the body through the lungs but translocate to essentially all organs. Compared to fine particles (PM2.5), they cause more pulmonary inflammation and are retained longer in the lung. Their toxicity is increased with smaller size, larger surface area, adsorbed surface material, and the physical characteristics of the particles. Exposure to PM0.1 induces cough and worsens asthma. Metal fume fever is a systemic disease of lung inflammation most likely caused by PM0.1. The disease is manifested by systemic symptoms hours after exposure to metal fumes, usually through welding. PM0.1 cause systemic inflammation, endothelial dysfunction, and coagulation changes that predispose individuals to ischemic cardiovascular disease and hypertension. PM0.1 are also linked to diabetes and cancer. PM0.1 can travel up the olfactory nerves to the brain and cause cerebral and autonomic dysfunction. Moreover, in utero exposure increases the risk of low birthweight. Although exposure is commonly attributed to traffic exhaust, monitored students in Ghana showed the highest exposures in a home near a trash burning site, in a bedroom with burning coils employed to abate mosquitos, in a home of an adult smoker, and in home kitchens during domestic cooking. The high point-source production and rapid redistribution make incidental exposure common, confound general population studies and are compounded by the lack of global standards and national reporting. The potential for PM0.1 to cause harm to health is great, but their precise role in many illnesses is still unknown and calls for more research.
Particulate matter (PM) is the principal component of air pollution. PM includes a range of particle sizes, such as coarse, fine, and ultrafine particles. Particles that are <100 nm in diameter are defined as ultrafine particles (UFPs). UFPs are found to a large extent in urban air as both singlet and aggregated particles. UFPs are classified into two major categories based on their source. Typically, UFPs are incidentally generated in the environment, often as byproducts of fossil fuel combustion, condensation of semivolatile substances or industrial emissions, whereas nanoparticles are manufactured through controlled engineering processes. The primary exposure mechanism of PM is inhalation. Inhalation of PM exacerbates respiratory symptoms in patients with chronic airway diseases, but the mechanisms underlying this response remain unclear. This review offers insights into the mechanisms by which particles, including UFPs, influence airway inflammation and discusses several mechanisms that may explain the relationship between particulate air pollutants and human health, particularly respiratory health. Understanding the mechanisms of PM-mediated lung injury will enhance efforts to protect at-risk individuals from the harmful health effects of air pollutants.
One of our era's greatest scourges is air pollution, on account not only of its impact on climate change but also its impact on public and individual health due to increasing morbidity and mortality. There are many pollutants that are major factors in disease in humans. Among them, Particulate Matter (PM), particles of variable but very small diameter, penetrate the respiratory system via inhalation, causing respiratory and cardiovascular diseases, reproductive and central nervous system dysfunctions, and cancer. Despite the fact that ozone in the stratosphere plays a protective role against ultraviolet irradiation, it is harmful when in high concentration at ground level, also affecting the respiratory and cardiovascular system. Furthermore, nitrogen oxide, sulfur dioxide, Volatile Organic Compounds (VOCs), dioxins, and polycyclic aromatic hydrocarbons (PAHs) are all considered air pollutants that are harmful to humans. Carbon monoxide can even provoke direct poisoning when breathed in at high levels. Heavy metals such as lead, when absorbed into the human body, can lead to direct poisoning or chronic intoxication, depending on exposure. Diseases occurring from the aforementioned substances include principally respiratory problems such as Chronic Obstructive Pulmonary Disease (COPD), asthma, bronchiolitis, and also lung cancer, cardiovascular events, central nervous system dysfunctions, and cutaneous diseases. Last but not least, climate change resulting from environmental pollution affects the geographical distribution of many infectious diseases, as do natural disasters. The only way to tackle this problem is through public awareness coupled with a multidisciplinary approach by scientific experts; national and international organizations must address the emergence of this threat and propose sustainable solutions.
Background:
Fuel oil-derived volatile organic compounds (VOCs) inhalation is associated with accidental marine spills. After the Prestige petroleum tanker sank off northern Spain in 2002 and the Deepwater Horizon oil rig catastrophe in 2009, subjects involved in environmental decontamination showed signs of ongoing or residual lung disease up to 5 y after the exposure.
Objectives:
We aimed at investigating mechanisms driving persistent respiratory disease by developing an animal model of inhalational exposure to fuel oil-derived VOCs.
Methods:
Female Wistar and Brown Norway (BN) rats and C57BL mice were exposed to VOCs produced from fuel oil mimicking the Prestige spill. Exposed animals inhaled the VOCs 2 h daily, 5 d per week, for 3 wk. Airway responsiveness to methacholine (MCh) was assessed, and bronchoalveolar lavage (BAL) and lung tissues were analyzed after the exposure and following a 2-wk washout.
Results:
Consistent with data from human studies, both strains of rats that inhaled fuel oil-derived VOCs developed airway hyperresponsiveness that persisted after the washout period, in the absence of detectable inflammation in any lung compartment. Histopathology and quantitative morphology revealed the development of peripherally distributed pulmonary emphysema, which persisted after the washout period, associated with increased alveolar septal cell apoptosis, microvascular endothelial damage of the lung parenchyma, and inhibited expression of vascular endothelial growth factor (VEGF).
Discussion:
In this rat model, fuel oil VOCs inhalation elicited alveolar septal cell apoptosis, likely due to DNA damage. In turn, the development of a peculiar pulmonary emphysema pattern altered lung mechanics and caused persistent noninflammatory airway hyperresponsiveness. Such findings suggest to us that humans might also respond to VOCs through physiopathological pathways different from those chiefly involved in typical cigarette smoke-driven emphysema in chronic obstructive pulmonary disease (COPD). If so, this study could form the basis for a novel disease mechanism for lasting respiratory disease following inhalational exposure to catastrophic fuel oil spills. https://doi.org/10.1289/EHP4178.
Additive manufacturing (AM) stands out as one of the promising technologies that have huge potential towards manufacturing industry. The study on additive manufacturing impact on the environment and occupational exposure are attracting growing attention recently. However, most of the researcher focus on desktop and fused deposition modelling type and less attention given to the industrial type of AM. Usually, during the selective laser sintering process, recycle powder will be used again to reduce cost and waste. This article compares the PM 2.5, carbon dioxide (CO 2 ) and total volatile organic compound (TVOC) concentration between virgin and recycles powder using polyamide-nylon (PA12) towards indoor concentration. Four phases of sampling involve during air sampling accordingly to the Industry Code of Practice on Indoor Air Quality 2010 by DOSH Malaysia. It was found that PM 2.5 and CO 2 concentration are mainly generated during the pre-printing process. The recycle powder tended to appear higher compared to virgin powder in terms of PM 2.5, and CO 2 . The peak value of PM 2.5 is 1452 µg/m ³ and CO 2 is 1218 ppm are obtained during the pre-printing process during 8 hours of sampling. TVOC concentration from recycling powder is slightly higher during the post- printing phase where confirm the influence of the powder cake and PA12 temperature from the printing process. In summary, this work proves that elective laser sintering (SLS) machine operators are exposed to a significant amount of exposure during the SLS printing process. Mitigation strategies and personal protective equipment are suggested to reduce occupational exposure.
Background:
While acrylates are well-known skin sensitisers, they are not classified as respiratory sensitisers although several cases of acrylate-induced occupational asthma (OA) have been reported.
Objectives:
The aim of this study was to evaluate the characteristics of acrylate-induced OA in a large series of cases and compare those with OA induced by other low-molecular-weight (LMW) agents.
Methods:
Jobs and exposures, clinical and functional characteristics, and markers of airway inflammation were analysed in an international, multicentre, retrospective cohort of subjects with OA ascertained by a positive inhalation challenge to acrylates (n= 55) or other LMW agents (n=418) including isocyanates (n=125).
Results:
Acrylate-containing glues were the most prevalent products and industrial manufacturing, dental work and beauty care were typical occupations causing OA. Work related rhinitis was more common in acrylate than isocyanate-induced asthma (p<0.001). The increase in post-challenge fractional exhaled nitric oxide (FeNO) was significantly greater in acrylate-induced OA (26.0, 8.2-38.0 ppb) than in OA induced by other LMW agents (3.0, -1.0-10.0 ppb, p<0.001) or isocyanates (5.0, 2.0-16.0 ppb, p=0.010). Multivariable models confirmed that OA induced by acrylates was significantly and independently associated with a post-challenge increase in FeNO (≥17.5 ppb).
Conclusions:
Acrylate-induced OA shows specific characteristics, concomitant work-related rhinitis and exposure-related increases in FeNO, suggesting that acrylates may induce asthma through different immunological mechanisms than other LMW agents. Our findings reinforce the need for a re-evaluation of the hazard classification of acrylates, and further investigation of the pathophysiological mechanisms underlying their respiratory sensitizing potential.
Additive manufacturing (commonly referred to as 3D printing) created an attractive approach for regenerative medicine research in musculoskeletal tissue engineering. Given the high number of fabrication technologies available, characterized by different working and physical principles, there are several related risks that need to be managed to protect operators. Recently, an increasing number of studies demonstrated that several types of 3D printers are emitters of ultrafine particles and volatile organic compounds whose harmful effects through inhalation, ingestion and skin uptake are known. Confirmation of danger of these products is not yet final, but this provides a basis to adopt preventive measures in agreement with the precautionary principle. The purpose of this investigation was to provide a useful tool to the researcher for managing the risks related to the use of different kinds of three-dimensional printers (3D printers) in the lab, especiallyconcerning orthopedic applications, and to define appropriate control measures. Particular attention was given to new emerging risks and to developing response strategies for a comprehensive coverage of the health and safety of operators.
The ISO 16000 standard series provide guidelines for emission measurements of volatile organic compounds (VOCs) from building materials. However, polymer‐based consumer products such as toys may also release harmful substances into indoor air. In such cases, the existing standard procedures are unsuitable for official control laboratories due to high costs for large emission testing chambers. This paper aims at developing and comparing alternative and more competitive methods for the emission testing of consumer products. The influence of the emission chamber size was investigated as smaller chambers are more suited to the common size of consumer products and may help to reduce the costs of testing. Comparison of the performance of a 203 l emission test chamber with two smaller chambers with the capacity of 24 l and 44 ml, respectively, was carried out by using a polyurethane reference material spiked with 14 VOCs during the course of 28 days. The area‐specific emission rates obtained in the small chambers were always similar to those of the 203 l reference chamber after a few hours. This implies that smaller chambers can provide at least useful numbers on the extent of polymer‐based consumer product emissions into indoor air, thereby supporting meaningful exposure assessments.
Little is known about emissions and exposure potential from vat polymerization additive manufacturing, a process that uses light-activated polymerization of a resin to build an object. Five vat polymerization printers (three stereolithography (SLA) and two digital light processing (DLP) were evaluated individually in a 12.85 m³ chamber. Aerosols (number, size) and total volatile organic compounds (TVOC) were measured using real-time monitors. Carbonyl vapors and particulate matter were collected for offline analysis using impingers and filters, respectively. During printing, particle emission yields (#/g printed) ranged from 1.3 ± 0.3 to 2.8 ± 2.6 x 10⁸ (SLA printers) and from 3.3 ± 1.5 to 9.2 ± 3.0 x 10⁸ (DLP printers). Yields for number of particles with sizes 5.6 to 560 nm (#/g printed) were 0.8 ± 0.1 to 2.1 ± 0.9 x 10¹⁰ and from 1.1 ± 0.3 to 4.0 ± 1.2 x 10¹⁰ for SLA and DLP printers, respectively. TVOC yield values (µg/g printed) ranged from 161 ± 47 to 322 ± 229 (SLA printers) and from 1281 ± 313 to 1931 ± 234 (DLP printers). Geometric mean mobility particle sizes were 41.1–45.1 nm for SLA printers and 15.3–28.8 nm for DLP printers. Mean particle and TVOC yields were statistically significantly higher and mean particle sizes were significantly smaller for DLP printers compared with SLA printers (p < 0.05). Energy dispersive X-ray analysis of individual particles qualitatively identified potential occupational carcinogens (chromium, nickel) as well as reactive metals implicated in generation of reactive oxygen species (iron, zinc). Lung deposition modeling indicates that about 15–37% of emitted particles would deposit in the pulmonary region (alveoli). Benzaldehyde (1.0–2.3 ppb) and acetone (0.7–18.0 ppb) were quantified in emissions from four of the printers and 4-oxopentanal (0.07 ppb) was detectable in the emissions from one printer. Vat polymerization printers emitted nanoscale particles that contained potential carcinogens, sensitizers, and reactive metals as well as carbonyl compound vapors. Differences in emissions between SLA and DLP printers indicate that the underlying technology is an important factor when considering exposure reduction strategies such as engineering controls.
Background:
Emerging reports suggest the potential for adverse health effects from exposure to emissions from some additive manufacturing (AM) processes. There is a paucity of real-world data on emissions from AM machines in industrial workplaces and personal exposures among AM operators.
Methods:
Airborne particle and organic chemical emissions and personal exposures were characterized using real-time and time-integrated sampling techniques in four manufacturing facilities using industrial-scale material extrusion and material jetting AM processes.
Results:
Using a condensation nuclei counter, number-based particle emission rates (ERs) (number/min) from material extrusion AM machines ranged from 4.1 × 1010 (Ultem filament) to 2.2 × 1011 [acrylonitrile butadiene styrene and polycarbonate filaments). For these same machines, total volatile organic compound ERs (μg/min) ranged from 1.9 × 104 (acrylonitrile butadiene styrene and polycarbonate) to 9.4 × 104 (Ultem). For the material jetting machines, the number-based particle ER was higher when the lid was open (2.3 × 1010 number/min) than when the lid was closed (1.5-5.5 × 109 number/min); total volatile organic compound ERs were similar regardless of the lid position. Low levels of acetone, benzene, toluene, and m,p-xylene were common to both AM processes. Carbonyl compounds were detected; however, none were specifically attributed to the AM processes. Personal exposures to metals (aluminum and iron) and eight volatile organic compounds were all below National Institute for Occupational Safety and Health (NIOSH)-recommended exposure levels.
Conclusion:
Industrial-scale AM machines using thermoplastics and resins released particles and organic vapors into workplace air. More research is needed to understand factors influencing real-world industrial-scale AM process emissions and exposures.
The paucity of information on the biological risks of photopolymers in additive manufacturing is a major challenge for the uptake of the technology in the construction of medical devices in dentistry. In this paper, the biocompatibility of methacrylates for denture bases, splints, retainers and surgical guides were evaluated using the innovative zebrafish embryo model, which is providing a high potential for toxicity profiling of photopolymers and has high genetic similarity to humans. Toxicological data obtained confirmed gradations of toxicity influenced by ethanol treatment, exposure scenarios and extraction vehicles. In direct exposure tests, juvenile fish exposed to non-treated methacrylates in ultrapure water showed accelerated toxicity endpoints compared to fish in transparent E3 medium. Similarly, toxic extracts induced mostly acute responses (embryonic mortality) in contrast to cumulative chronic (sublethal and teratogenic effects) in direct exposure. Methacrylates composed of >60% Ethoxylated bisphenol A dimethacrylate produced a relatively lower conversion rate in FTIR spectroscopy, but were safe in zebrafish bioassays after ethanol treatment. The study affirms that biocompatibility was influenced primarily by physico-chemical characteristics of the materials, which subsequently influenced their residual monomer content before and after immersion in ethanol. Given the precautionary implications of the study, we propose a 3-tiered approach i.e. using approved materials, apposite manufacturing parameters and post-processing techniques that together guarantee optimal results for medical devices.
Statement of Significance:
This study is timely and relevant since there is limited published literature that precisely describes the toxicological properties of additively manufactured methacrylates despite their increased popularity for medical devices. While it is generally accepted that the zebrafish excels as a model system for developmental toxicity, a further examination of its utility in this study using different protocols provides basis for its consideration and adoption at a crucial time when there is a lack of consensus regarding the most suited biological assessment methods for medical devices.
Printing devices are known to emit chemicals into the indoor atmosphere. Understanding factors that influence release of chemical contaminants from printers is necessary to develop effective exposure assessment and control strategies. In this study, a desktop fused deposition modeling (FDM) 3-D printer using acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) filaments and two monochrome laser printers were evaluated in a 0.5 m³ chamber. During printing, chamber air was monitored for vapors using a real-time photoionization detector (results expressed as isobutylene equivalents) to measure total volatile organic compound (TVOC) concentrations, evacuated canisters to identify specific VOCs by off-line gas chromatography-mass spectrometry (GC-MS) analysis, and liquid bubblers to identify carbonyl compounds by GC-MS. Airborne particles were collected on filters for off-line analysis using scanning electron microscopy with an energy dispersive x-ray detector to identify elemental constituents. For 3-D printing, TVOC emission rates were influenced by a printer malfunction, filament type, and to a lesser extent, by filament color; however, rates were not influenced by the number of printer nozzles used or the manufacturer's provided cover. TVOC emission rates were significantly lower for the 3-D printer (49 to 3552 µg h⁻¹) compared to the laser printers (5782 to 7735 µg h⁻¹). A total of 14 VOCs were identified during 3-D printing that were not present during laser printing. 3-D printed objects continued to off-gas styrene, indicating potential for continued exposure after the print job is completed. Carbonyl reaction products were likely formed from emissions of the 3-D printer, including 4-oxopentanal. Ultrafine particles generated by the 3-D printer using ABS and a laser printer contained chromium. Consideration of the factors that influenced the release of chemical contaminants (including known and suspected asthmagens such as styrene and 4-oxopentanal) from a FDM 3-D printer should be made when designing exposure assessment and control strategies.
Residential proximity to industrial sites has been associated with adverse effects on human health. Children are more susceptible to airborne environmental exposure because their immune and respiratory systems are still developing. This study aimed to investigate whether living close to an oil terminal in Genoa where there is higher VOCs exposure is associated with an increased rate of school absenteeism because of disease in primary school children. Five schools were chosen for the recruitment of children and students residing in the industrial site (A) were compared to those living in residential sites (B). Sixty-six of the 407 students involved in the project were also selected for VOC monitoring. Source apportionment was carried out by comparing profiles of VOCs; principal component analysis was performed to study the correlation between profiles, and Kriging interpolation model was used to extend profiles to all participants. The concentration means of total VOCs were significantly higher in the industrial areas compared to controls. Adjusting for potential confounders, children who lived in area A had a significantly higher risk of being absent from school due to sore throat, cough, and cold compared to controls. o -Xylene, which is dispersed during the industrial activity, showed clear evidence of a significant association with respiratory symptoms.
Desktop three-dimensional (3D) printers are becoming commonplace in business offices, public libraries, university labs and classrooms, and even private homes; however, these settings are generally not designed for exposure control. Prior experience with a variety of office equipment devices such as laser printers that emit ultrafine particles (UFP) suggests the need to characterize 3D printer emissions to enable reliable risk assessment. The aim of this study was to examine factors that influence particulate emissions from 3D printers and characterize their physical properties to inform risk assessment. Emissions were evaluated in a 0.5-m3 chamber and in a small room (32.7 m3) using real-time instrumentation to measure particle number, size distribution, mass, and surface area. Factors evaluated included filament composition and color, as well as the manufacturer-provided printer emissions control technologies while printing an object. Filament type significantly influenced emissions, with acrylonitrile butadiene styrene (ABS) emitting larger particles than polylactic acid (PLA), which may have been the result of agglomeration. Geometric mean particle sizes and total particle (TP) number and mass emissions differed significantly among colors of a given filament type. Use of a cover on the printer reduced TP emissions by a factor of 2. Lung deposition calculations indicated a threefold higher PLA particle deposition in alveoli compared to ABS. Desktop 3D printers emit high levels of UFP, which are released into indoor environments where adequate ventilation may not be present to control emissions. Emissions in nonindustrial settings need to be reduced through the use of a hierarchy of controls, beginning with device design, followed by engineering controls (ventilation) and administrative controls such as choice of filament composition and color.
This study investigates the influence of three environmental indoor parameters (i.e., temperature, relative humidity, and air exchange rate) on the emission of 13 volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) during incense burning. Experiments have been carried out using an environmental test chamber. Statistical results from a classical two-level full factorial design highlight the predominant effect of ventilation on emission factors. The higher the ventilation, the higher the emission factor. Moreover, thanks to these results, an estimation of the concentration range for the compounds under study can be calculated and allows a quick look of indoor pollution induced by incense combustion. Carcinogenic substances (i.e., benzene, benzo(a)pyrene, and formaldehyde) produced from the incense combustion would be predicted in typical living indoors conditions to reach instantaneous concentration levels close to or higher than air quality exposure threshold values.
Objective: The use of chemicals for building prosthetic sockets present the possibility of being hazardous and unsafe due to off-gassing. The purpose of the present study was to investigate if freshly made materials used in prosthetic sockets causes off-gassing that would penetrate the skin and cause damage to the kidneys or blood. Design: Cross-sectional study. Methods: In this research, the off-gassing effects during the initial curing process of styrene monomer, vinyl ester resin, epoxy methacrylate resin, benzene-1, 3-dimethaneamine, trimethylhexanedlamine, and paratertiarybutylphenol were analyzed. Acid detection strips were placed inside newly fabricated mock-prosthetic sockets and left overnight in a closed environment to find out if acid was present in the invisible fumes. The plastic was worn by 9 subjects and urinalysis was made after 48 hours to test for any kidney or blood toxicity of the resins. Results: After wearing the plastic cuff for 48 hours, the ratio of protein to creatinine in the urine was raised to an abnormal level in five out of nine subjects. Four out of the nine subjects showed normal protein to creatinine ratios after wearing the device. The results showed that damage to the kidney occurred from wearing the resins after curing in half of the subjects. Conclusions: It is very important to conduct patient intakes which includes the assessment of renal function. Off-gassing in vented chambers may be needed to protect both prosthetists and patients.
UV printing inks are considered safer than the classical inks; however, despite being on the outer surface of the packaging material, their components can migrate into foodstuffs and can give rise to contamination. Photoinitiators are a part of the formulation of printing inks, being an important class of migrant, for which there have been more than 100 incidents of contamination of packaged food with photoinitiators reported through RASFF (Rapid Alert System for Food and Feed) alerts in the EU. In this review the process of photo-polymerisation is explained in depth to provide an insight into the complexity of the process, and the diversity of potential contaminants together with their degradation products. The critical factors affecting the migration process itself are reviewed, together with analytical methods and the current legislation in the EU and other parts of the world.
Quantifying the impact of air pollution on the public's health has become an increasingly critical component in policy discussion. Recent data indicate that more than 70% of the world population lives in cities. Several studies reported that current levels of air pollutants in urban areas are associated with adverse health risks, namely, cardiovascular diseases and lung cancer. IARC recently classified outdoor air pollution and related particulate matter (PM) as carcinogenic to humans. Despite the air quality improvements observed over the last few years, there is still continued widespread exceedance within Europe, particularly regarding PM and nitrogen oxides (NOx). The European Air Quality Directive 2008/50/EC requires Member States to design appropriate air quality plans for zones where air quality does not comply with established limit values. However, in most cases, air quality is only quantified using a combination of monitored and modeled data and no health impact assessment is carried out. An integrated approach combining the effects of several emission abatement measures on air quality, impacts on human health, and associated implementation costs enables an effective cost-benefit analysis and an added value to the decision-making process. Hence, this review describes the basic steps and tools for integrating health into air quality assessment (health indicators, exposure-response functions). In addition, consideration is given to two major outdoor pollutants: PM and NO2. A summary of the health metrics used to assess the health impact of PM and NO2 and recent epidemiologic data are also described.
Ambient air pollution (AAP) and particulate matters (PM) have been closely associated with adverse health effects such as respiratory disease and cardiovascular diseases. Previous studies have examined the adverse health effects associated with short- and long-term exposure to AAP and outdoor PM on respiratory disease. However, the effect of PM size (PM2.5 and PM10) on cardiovascular disease has not been well studied. Thus, it remains unclear how the size of the inhalable particles (coarse, fine, or ultrafine) affects mortality and morbidity. Airborne PM concentrations are commonly used for ambient air quality management worldwide, owing to the known effects on cardiorespiratory health. In this article, we assess the relationship between cardiovascular diseases and PM, with a particular focus on PM size. We discuss the association of PM2.5 and PM10, nitrogen dioxide (NO2), and elemental carbon with mortality and morbidity due to cardiovascular diseases, stroke, and altered blood pressure, based on epidemiological studies. In addition, we provide evidence that the adverse health effects of AAP and PM are more pronounced among the elderly, children, and people with preexisting cardiovascular and respiratory conditions. Finally, we critically summarize the literature pertaining to cardiovascular diseases, including atherosclerosis and stroke, and introduce potential studies to better understand the health significance of AAP and PM on cardiovascular
disease.
The immunostimulatory effects of the representative dental resin monomer 2-hydroxyethyl methacrylate (HEMA), a HEMA derivative that does not contain a double bond (2-hydroxyethyl isobutyrate, HEIB), and polymerized water-soluble oligomers of HEMA (PHEMA) were investigated. It is known that expression levels of either or both of CD54 and CD86 in THP-1 cells are increased by exposure to sensitizing substances. In this study, the expression levels of CD54 and CD86, the production of reactive oxygen species (ROS), and the viability of the cells were measured after 24 h of incubation with these materials at different concentrations. The concentrations of the materials that induced the expression of both CD54 and CD86 were low in the following order: NiSO4, HEMA, and methyl methacrylate (MMA). These results indicate that these dental resin monomers have lower sensitizing potentials than NiSO4. Although HEIB, which lacks a double bond, resulted in negligible ROS production and reduced cytotoxicity than HEMA, it induced the expression of CD54 and CD86. Comparison of the results for HEMA and HEIB indicates that dental resin monomer-induced sensitization may be related not only to the oxidative stress related to the methacryloyl group but also to the structures of these compounds. Of particular interest is the result that a water-soluble PHEMA oligomer with a relatively high-molecular weight also exhibited negligible cytotoxicity, whereas the expression level of CD54 increased after exposure to PHEMA at a high concentration. This result serves as a warning that polymerized substances also have the potential to induce sensitization. This study provides insight into the nature of allergic responses to dental resin materials in clinical use and may facilitate the development of more biocompatible restorative materials in the future.
Studies of unexplained symptoms observed in chemically sensitive subjects have increased the awareness of the relationship between neurological and immunological diseases due to exposure to volatile organic compounds (VOCs). However, there is no direct evidence that links exposure to low doses of VOCs and neurological and immunological dysfunction. We review animal model data to clarify the role of VOCs in neuroimmune interactions and discuss our recent studies that show a relationship between chronic exposure of C3H mice to low levels of formaldehyde and the induction of neural and immune dysfunction. We also consider the possible mechanisms by which VOC exposure can induce the symptoms presenting in patients with a multiple chemical sensitivity.
Purpose
– This study aims to investigate the potential impacts of rapid prototyping systems on the health and safety of operators and the environment, a growing concern given its wide-spread use in industry and academia.
Design/methodology/approach
– Materials, processing and equipment features were used to identify potential health and safety risks and hazards, as well as environmental effects.
Findings
– The study concludes with a “best practices” guide for rapid prototyping laboratories and service bureaus.
Originality/value
– A thorough literature search revealed that Stephen M. Deak, the Rapid Prototyping Department Manager at Hasbro Inc., is the pioneer of the safety and health concerns in the rapid prototyping area. He is the only person to publish papers in this field in addition to these authors’ recent publications. His papers focused on the rapid prototyping laboratory safety guidelines and safe work practices in the rapid prototyping area.
Short-term effects of air pollutants on respiratory mortality and morbidity have been consistently reported but usually studied separately. To more completely assess air pollution effects, we studied hospitalisations for respiratory diseases together with out-of-hospital respiratory deaths.
A time-stratified case-crossover study was carried out in six Italian cities from 2001 to 2005. Daily particulate matter (particles with a 50% cut-off aerodynamic diameter of 10 μm (PM 10 )) and nitrogen dioxide (NO 2 ) associations with hospitalisations for respiratory diseases (n = 100 690), chronic obstructive pulmonary disease (COPD) (n = 38 577), lower respiratory tract infections (LRTI) among COPD patients (n = 9886) and out-of-hospital respiratory deaths (n = 5490) were estimated for residents aged ≥35 years.
For an increase of 10 μg·m ⁻³ in PM 10 , we found an immediate 0.59% (lag 0–1 days) increase in hospitalisations for respiratory diseases and a 0.67% increase for COPD; the 1.91% increase in LRTI hospitalisations lasted longer (lag 0–3 days) and the 3.95% increase in respiratory mortality lasted 6 days. Effects of NO 2 were stronger and lasted longer (lag 0–5 days). Age, sex and previous ischaemic heart disease acted as effect modifiers for different outcomes.
Analysing multiple rather than single respiratory events shows stronger air pollution effects. The temporal relationship between the pollutant increases and hospitalisations or mortality for respiratory diseases differs.
This comprehensive review introduces occupational (industrial) hygienists and toxicologists to the seven basic additive manufacturing (AM) process categories. Forty-six articles were identified that reported real-world measurements for all AM processes, except sheet lamination. Particles released from powder bed fusion (PBF), material jetting (MJ), material extrusion (ME), and directed energy deposition (DED) processes exhibited nanoscale to submicron scale; real-time particle number (mobility sizers, condensation nuclei counters, miniDiSC, electrical diffusion batteries) and surface area monitors (diffusion chargers) were generally sufficient for these processes. Binder jetting (BJ) machines released particles up to 8.5 µm; optical particle sizers (number) and laser scattering photometers (mass) were sufficient for this process. PBF and DED processes (powdered metallic feedstocks) released particles that contained respiratory irritants (chromium, molybdenum), central nervous system toxicants (manganese), and carcinogens (nickel). All process categories, except those that use metallic feedstocks, released organic gases, including (but not limited to), respiratory irritants (toluene, xylenes), asthmagens (methyl methacrylate, styrene), and carcinogens (benzene, formaldehyde, acetaldehyde). Real-time photoionization detectors for total volatile organics provided useful information for processes that utilize polymer feedstock materials. More research is needed to understand 1) facility-, machine-, and feedstock-related factors that influence emissions and exposures, 2) dermal exposure and biological burden, and 3) task-based exposures. Harmonized emissions monitoring and exposure assessment approaches are needed to facilitate inter-comparison of study results. Improved understanding of AM process emissions and exposures is needed for hygienists to ensure appropriate health and safety conditions for workers and for toxicologists to design experimental protocols that accurately mimic real-world exposure conditions.
ABBREVIATIONS ABS : acrylonitrile butadiene styrene; ACGIH® TLV® : American Conference of Governmental Industrial Hygienists Threshold Limit Value; ACH : air change per hour; AM : additive manufacturing; ASA : acrylonitrile styrene acrylate; AVP : acetone vapor polishing; BJ : binder jetting; CAM-LEM : computer-aided manufacturing of laminated engineering materials; CNF : carbon nanofiber; CNT : carbon nanotube; CP : co-polyester; CNC : condensation nuclei counter; CVP : chloroform vapor polishing; DED : directed energy deposition; DLP : digital light processing; EBM : electron beam melting; EELS : electron energy loss spectrometry; EDB : electrical diffusion batteries; EDX : energy dispersive x-ray analyzer; ER : emission rate; FDM™ : fused deposition modeling; FFF : fused filament fabrication; IAQ : indoor air quality; LSP : laser scattering photometer; LCD : liquid crystal display; LDSA : lung deposited particle surface area; LOD : limit of detection; LOM : laminated object manufacturing; LOQ : limit of quantitation; MCE : mixed cellulose ester filter; ME : material extrusion; MJ : material jetting; OEL : occupational exposure limit; OPS : optical particle sizer; PBF : powder bed fusion; PBZ : personal breathing zone; PC : polycarbonate; PEEK : poly ether ether ketone; PET : polyethylene terephthalate; PETG : Polyethylene terephthalate glycol; PID : photoionization detector; PLA : polylactic acid; PM1 : particulate matter with aerodynamic diameter less than 1 µm; PM2.5 : particulate matter with aerodynamic diameter less than 2.5 µm; PM10 : particulate matter with aerodynamic diameter less than 10 µm; PSL : plastic sheet lamination; PVA : polyvinyl alcohol; REL : recommended exposure limit; SDL : selective deposition lamination; SDS : safety data sheet; SEM : scanning electron microscopy; SL : sheet lamination; SLA : stereolithography; SLM : selective laser melting; SMPS : scanning mobility particle sizer; SVOC : semi-volatile organic compound; TEM : transmission electron microscopy; TGA : thermal gravimetric analysis; TPU : thermo polyurethane; UAM : ultrasonic additive manufacturing; UC : ultrasonic consolidation; TVOC : total volatile organic compounds; TWA : time-weighted average; VOC : volatile organic compound; VP : vat photopolymerization
As additive manufacturing becomes more prevalent in industrial manufacturing facilities, so does human interaction with these machines. In this study, we characterized the size-resolved concentrations of particulate matter (PM, from ≈ 11 to 20,000 nm in size) and volatile organic compounds (VOC) resulting from a material-jetting (Projet 5500X), multi jet fusion (HP MJF 4200), and photopolymerization (Carbon 3D continuous liquid interface production). During all processes, PM concentrations were below the OSHA limits and ultrafine PM (PM0.1) concentrations were well below levels commonly observed for fused deposition modeling printers. PM and total volatile organic compound (VOC) concentrations during printing were close to background levels for the HP MJF printer and HP MJF post processing station. However, the mean particle size of the powder used (PA 12) was above the upper detection limit of the instrument (20 μm). Carbon 3D total VOC levels were highest during part post processing. Cyclic PM emissions from the Projet 5500X printer suggested higher PM emissions during cooling fan activity. VOC analysis revealed high concentrations of HP ink solvents (2-Pyrrolidinone and Triethylene glycol), potential exposure to fluorinated compounds and photoresin VOCs during Carbon 3D post-processing, and exposure to photo-resin compounds during Projet 5500X printing. This study indicates that proper exhaust and facility air exchange can limit concentrations of PM and VOCs and therefore particular attention to the building design and ventilation system should be taken into consideration for additive manufacturing facilities to mitigate potential human exposure and associated health risks.
Fused filament fabrication (FFF) 3D printers are increasingly used in industrial, academic, military, and residential sectors, yet their emissions and associated user exposure scenarios are not fully described. Characterization of potential user exposure and environmental releases requires robust investigation. During operation, common FFF 3D printers emit varying amounts of ultrafine particles (UFPs) depending upon feedstock material and operation procedures. Volatile organic compounds associated with these emissions exhibit distinct odors; however, the UFP portion is largely imperceptible by humans. This investigation presents straightforward computational modeling as well as experimental validation to provide actionable insights for the proactive design of lower exposure spaces where 3D printers may be used. Specifically, data suggest that forced clean airflows may create lower exposure spaces, and that computational modeling might be employed to predict these spaces with reasonable accuracy to assist with room design. The configuration and positioning of room air ventilation diffusers may be a key factor in identifying lower exposure spaces. A workflow of measuring emissions during a printing process in an ANSI/CAN/UL 2904 environmental chamber was used to provide data for computational fluid dynamics (CFD) modeling of a 6 m2 room. Measurements of the particle concentrations in a Class 1000 clean room of identical geometry were found to pass the Hanna test for agreement between model and experimental data, validating the findings.
Fine and ultra-fine particulate matter (PM) are major constituents of urban air pollution and recognized risk factors for cardiovascular diseases. This review examined the effects of PM exposure on vascular tissue. Specific mechanisms by which PM affects the vasculature include inflammation, oxidative stress, actions on vascular tone and vasomotor responses, as well as atherosclerotic plaque formation. Further, there appears to be a greater PM exposure effect on susceptible individuals with pre-existing cardiovascular conditions.
In this pilot-scale study, a wide range of potential emissions were evaluated for four types of additive manufacturing (AM) machines. These included material extrusion (using acrylonitrile-butadiene-styrene [ABS]); material jetting (using liquid photopolymer); powder bed fusion (using nylon); and vat photopolymerization (using liquid photopolymer) in an industrial laboratory setting. During isolated operation of AM machines, adjacent area samples were collected for compounds of potential concern (COPCs), including total and individual volatile organic compounds (VOCs), nano- and micron-sized particulate matter, and inorganic gases. A total of 61 compounds were also sampled using a canister followed by gas chromatography and mass spectrometry analysis. Most COPCs were not detected or were measured at concentrations far below relevant occupational exposure limits (OELs) during AM machine operations. Submicron particles, predominantly nanoparticles, were produced during material extrusion printing using ABS at approximately 12,000 particles per cubic centimeter (p cm⁻³) above background. After subtracting the mean background concentration, the mean concentration for material extrusion printing operations correlated with a calculated emission rate of 2.8 × 10¹⁰ p min⁻¹ under the conditions tested. During processing of parts produced using material jetting or powder bed fusion, emissions were generally negligible, although concentrations above background of respirable and total dust were measured during processing of powder bed fusion parts. Results of this pilot-scale study indicate that airborne emissions associated with AM operations are variable, depending on printing and parts handling processes, raw materials, and ventilation characteristics. Although personal samples were not collected in this pilot-scale study, the results can be used to inform future exposure assessments. Based on the results of this evaluation, measurement of submicron particles emitted during material extrusion printing operations and dust associated with handling parts manufactured using powder bed fusion processes should be included in exposure assessments.
Volatile organic compounds (VOCs) have shown potential as non-invasive breath biomarkers for lung cancer, but their unclear biological origin currently limits clinical applications. This systematic review explores headspace analysis of VOCs in patient-derived body fluids and lung cancer cell lines to pinpoint lung cancer-specific VOCs and uncover their biological origin.
A search was performed in the databases MEDLINE and Web of Science. Twenty-two articles were included in this systematic review.
Since there is no standardised approach to analyse VOCs, a plethora of techniques and matrices/cell lines were explored, which is reflected in the various VOCs identified. However, comparing VOCs in the headspace of urine, blood and pleural effusions from patients and lung cancer cell lines showed some overlapping VOCs, indicating their potential use in lung cancer diagnosis.
This review demonstrates that VOCs are promising biomarkers for lung cancer. However, due to lack of inter-matrix consensus, standardised prospective trials will have to be conducted to validate clinically relevant biomarkers.
The aim of this study was to determine concentrations of particulates and volatile organic compounds (VOCs) emitted from 3D printers using polylactic acid (PLA) filaments at a university workroom to assess exposure and health risks in an occupational setting. Under typical-case (one printer) and worst-case (three printers operating simultaneously) scenarios, particulate concentration (total and respirable), VOCs and formaldehyde were measured. Air samples were collected in the printing room and adjacent hallway. Size-resolved levels of nano-diameter particles were also collected in the printing room. Total particulate levels were higher in the worst-case scenario (0.7 mg/m³) vs. typical-case scenario (0.3 mg/m³). Respirable particulate and formaldehyde concentrations were similar between the two scenarios. Size-resolved measurements showed that most particles ranged from approximately 27 to 116 nm. Total VOC levels were approximately 6-fold higher during the worst-case scenario vs. typical situation with isopropyl alcohol being the predominant VOC. Airborne concentrations in the hallway were generally lower than inside the printing room. All measurements were below their respective occupational exposure limits. In summary, emissions of particulates and VOCs increased when multiple 3D printers were operating simultaneously. Airborne levels in the adjacent hallway were similar between the two scenarios. Overall, data suggest a low risk of significant and persistent adverse health effects. Nevertheless, the health effects attributed to 3D printing are not fully known and adherence to good hygiene principles is recommended during use of this technology.
Despite the potential benefits of photopolymerization-based additive manufacturing, photochemical reactions in free-radical polymerization rarely proceed to completion, leading to the accumulation of residual monomer in polymer networks. In this novel study, we examined an array of methacrylate polymers for denture bases (>60 % Bis-EMA and 15–25 % proprietary methacrylic oligomer), orthodontic appliances (>70 % proprietary methacrylic oligomer, <20 % glycol methacrylate and <5 % pentamethyl-piperidyl sebucate) and implant surgical guides (≥75 % Bis-EMA and 30–50 % diurethane dimethacrylate, mixture of isomers) using headspace gas chromatography-mass spectrometry. Experimental data reported herein show that a substantial proportion of chemical compounds observed in the methacrylates decreased with post-illumination and the applied ethanol treatment. In the absence of residual methyl methacrylate, other potentially toxic acrylic esters were observed thus emphasizing the need to thoroughly scrutinize additively manufactured dental devices prior to their use. In the long term, standards for medical devices in dentistry could be revised to reflect the current trends in biomaterials and precursors they are generated from.
Acrylates are synthetic thermoplastic resins used in a multitude of products, ranging from bone cement to artificial nails. They represent an important and increasing cause of both occupational and nonoccupational allergic contact dermatitis. Isobornyl acrylate, an acrylic monomer found within ultraviolet‐cured inks, adhesives and various medical devices for diabetes, has emerged as an important sensitizer. In addition, long‐lasting nail products have played a significant role in the increased prevalence of acrylate allergy. Sensitized individuals classically present with facial or eyelid dermatitis, and some patients experience associated fingertip and nail changes. This manuscript reviews these two important sources of acrylate allergy and summarizes other potential new exposures, including surgical glues and wound‐care products.
Objectives
Due to their small size, ultrafine particles (UFP) are believed to exert higher toxicity than larger particles. As numerous studies on health effects of UFP have been published since the last systematic review in 2013, we aim to systematically review the new literature.
Methods
We searched MEDLINE and the specialized LUDOK database for studies published between 01.01.2011 and 11.05.2017 investigating health effects of ambient air pollution-related UFP. We included epidemiologic studies containing UFP measures and quantifiable measures of associations. Relevant data were extracted on the basis of previously developed evaluation criteria.
Results
We identified 85 original studies, conducting short-term (n = 75) and long-term (n = 10) investigations. Panel (n = 32), scripted exposure with predefined settings (n = 16) or time series studies (n = 11) were most frequent. Thirty-four studies adjusted for at least one other pollutant. Most consistent associations were identified for short-term effects on pulmonary/systemic inflammation, heart rate variability and blood pressure.
Conclusions
The evidence suggests adverse short-term associations with inflammatory and cardiovascular changes, which may be at least partly independent of other pollutants. For the other studied health outcomes, the evidence on independent health effects of UFP remains inconclusive or insufficient.
The aim of this study was to measure the concentrations of gaseous and particulate contaminants originated from additive manufacturing operations and post-processes in an occupational setting when plastics were used as feedstock materials. Secondary aims were to evaluate the concentration levels based on proposed exposure limits and target values and to propose means to reduce exposure to contaminants released in additive manufacturing processes. Volatile organic compounds were sampled with Tenax® TA adsorption tubes and analyzed with thermo desorption gas chromatography-mass spectrometry instrument. Carbonyl compounds were sampled with DNPH-Silica cartridges and analyzed with high-performance liquid chromatography device. Particles were measured with P-Trak instrument and indoor air quality was sampled with IAQ-Calc instrument. Dust mass concentrations were measured simultaneously with DustTrak DRX instrument and IOM-samplers. Particle concentrations were at highest (2070-81 890 #/cm³ mean) during manufacturing with methods where plastics were thermally processed. Total volatile organic compounds concentrations, in contrast, were low (113-317 µg/m³ mean) during manufacturing with such methods, and vat photopolymerization method. However, total volatile organic compounds concentrations of material jetting and multi jet fusion methods were higher (1114-2496 µg/m³ mean), perhaps because of material and binder spraying, where part of the spray can become aerosolized. Chemical treatment of manufactured objects was found to be a severe volatile organic compounds source as well. Formaldehyde was detected in low concentrations (3-40 µg/m³) in all methods except for material jetting method, in addition to several other carbonyl compounds. Notable dust concentrations (1.4-9.1 mg/m³) were detected only during post-processing of powder bed fusion and multi jet fusion manufactured objects. Indoor air quality parameters were not found to be notably impacted by manufacturing operations. Only low concentrations (below 2 ppm) of CO were detected during several manufacturing processes. All studied additive manufacturing operations emitted potentially harmful contaminants into their environments, which should be considered in occupational additive manufacturing and workplace design. According to the measured contaminant levels it is possible that adverse additive manufacturing related health effects may occur amongst exposed workers.
Purpose
This paper aims to measure exposures to airborne contaminants during three-dimensional (3-D) printing and post-processing tasks in an industrial workplace.
Design/methodology/approach
Contaminant concentrations were assessed using real-time particle number (0.007 to 1 µm) and total volatile organic compound (TVOC) monitors and thermal desorption tubes during various tasks at a manufacturing facility using fused deposition modeling (FDMTM) 3-D printers. Personal exposures were measured for two workers using nanoparticle respiratory deposition samplers for metals and passive badges for specific VOCs.
Findings
Opening industrial-scale FDMTM 3-D printer doors after printing, removing desktop FDMTM 3-D printer covers during printing, acetone vapor polishing (AVP) and chloroform vapor polishing (CVP) tasks all resulted in transient increases in levels of submicrometer-scale particles and/or organic vapors, a portion of which enter the workers’ breathing zone, resulting in exposure. Personal exposure to quantifiable levels of metals in particles <300 nm were 0.02 mg/m³ for aluminum, chromium, copper, iron and titanium during FDMTM printing. Personal exposures were 0.38 to 6.47 mg/m³ for acetone during AVP and 0.18 mg/m³ for chloroform during CVP.
Originality/value
Characterization of tasks provided insights on factors that influenced contaminant levels, and in turn exposures to various particles, metals < 300 nm and organic vapors. These concentration and exposure factors data are useful for identifying tasks and work processes to consider for implementation of new or improved control technologies to mitigate exposures in manufacturing facilities using FDMTM 3-D printers.
Nanomaterials are invading our environment due to their increasing use in a very broad range of sectors making human exposure foreseeable during the life cycle of these materials. Inhalation is one of the most frequent routes of exposure in case of unintentional exposure and the small size of nanomaterials allows them to reach the deep lung. Understanding the fate and effects of nanomaterials is a great challenge for scientists as they exhibit a huge physico-chemical diversity that drives their biological reactivity. It is critical to determine the fate of nanomaterials at their route of entry in the organism as this will determine their local and/or systemic effects. In this review we will describe the epithelial barriers and the clearance processes of the respiratory tract. The mechanisms involved in the internalization of nanomaterials by respiratory cells and their ability to cross the epithelial barrier will be presented, highlighting methodologies and the role of the nanomaterial physico-chemical properties.
Background:
Dental technicians (DTs) are at increased risk for allergic contact sensitization.
Objectives:
To assess the current spectrum of occupational sensitization in DTs with occupational contact dermatitis (OCD).
Methods:
A retrospective analysis of Information Network of Departments of Dermatology patch test data from the years 2001-2015 concerning DTs with OCD was performed.
Results:
Patients of the study group (226 DTs with OCD) were significantly more often diagnosed with allergic contact dermatitis (37.6% versus 18.5%; p = 0.0002) than patients of the control group (124 DTs without OCD). In the study group, positive reactions were most frequently observed to methacrylates and/or acrylates (n = 67). Of these, 61 patients showed positive reactions to at least one of the five most frequent allergens in this group, namely 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, methyl methacrylate, ethyl methacrylate, and/or ethylene glycol dimethacrylate. In contrast, no positive reactions to diurethane dimethacrylate (DUDMA) occurred. Among allergens of the German Contact Dermatitis Research Group series 'dental metals', positive reactions were less frequent and were mainly to palladium chloride (n = 6).
Conclusions:
The present data analysis showed that the sensitization spectrum and spectrum of cross-reactivity are largely unchanged as compared with the 1990s. It can be concluded that test recommendations are still valid and useful, except for the methacrylate DUDMA, which could be omitted.
This article presents a comprehensive review of scientific literature concerning the blooming of additives on the surface of polymers, a phenomenon that depends on the solubility of an additive in a polymer and occurs in a time that depends on the diffusion coefficient of the additive in the polymer. Blooming is an important phenomenon as its occurrence can modify the material properties and lower its resistance to degradation. We report the parameters that influence the occurrence of blooming such as temperature, polymer morphology, additive shape and size. We also highlight the main fields in which the blooming was studied, the consequences of blooming on the material properties and the various characterization methods that are able to analyze the blooming phenomenon in situ. We focused next on the biomedical field, as blooming of additives on the surface of medical devices, especially those that are implanted or in contact with body fluids, can impact the device biocompatibility and represent a risk for the patient.
Background:
Acrylic monomers (acrylates), methacrylates and cyanoacrylates all cause asthma by respiratory sensitization. Occupational inhalation exposures occur across a variety of industries including health care and dental work, beauty, laboratory science, assembly and plastic moulding.
Aims:
To examine notifications of occupational asthma caused by acrylic compounds from a UK-based regional surveillance scheme, in order to highlight prevalent exposures and trends in presentation.
Methods:
Retrospective review of all cases reported to the SHIELD surveillance scheme for occupational asthma, West Midlands, UK between 1989 and 2014. Patient data were gathered on demographics, employment, asthma symptoms and diagnostic investigations including serum immunological testing, serial peak flow analysis and specific inhalation challenge tests. Descriptive statistics were used to illustrate worker characteristics and evidence for sensitization to acrylic compounds.
Results:
There were 20 affected patients out of 1790 total cases of occupational asthma (1%); all cases were confirmed by OASYS (Occupational Asthma SYStem) analysis of serial peak flow measurements, with three additional positive specific inhalation challenge tests. Three out of 20 (15%) patients were current smokers and 11/20 (55%) were atopic. A variety of exposures and industries were implicated including: manufacturing, health care, beauty and printing and a novel presentation seen in teachers exposed to floor adhesives.
Conclusions:
This is the largest reported series of occupational asthma caused by acrylic compounds, which remain an important aetiological factor in this disease. Exposure occurs in a variety of industries, particularly in manufacturing and is seen with other, perhaps better recognized sensitizing agents such as isocyanates and epoxy resins.
Objectives:
Additive manufacturing, which is more colloquially referred to as 3D printing, is quickly approaching mainstream adoption as a highly flexible processing technique that can be applied to plastic, metal, ceramic, concrete and other building materials. However, taking advantage of the tremendous versatility associated with in situ photopolymerization as well as the ability to select from a variety of preformed processible polymers, 3D printing predominantly targets the production of polymeric parts and models. The goal of this review is to connect the various additive manufacturing techniques with the monomeric and polymeric materials they use while highlighting emerging material-based developments.
Methods:
Modern additive manufacturing technology was introduced approximately three decades ago but this review compiles recent peer-reviewed literature reports to demonstrate the evolution underway with respect to the various building techniques that differ significantly in approach as well as the new variations in polymer-based materials being employed.
Results:
Recent growth of 3D printing has been dramatic and the ability of the various platform technologies to expand from rapid production prototypic models to the greater volume of readily customizable production of working parts is critical for continued high growth rates. This transition to working part production is highly dependent on adapting materials that deliver not only the requisite design accuracy but also the physical and mechanical properties necessary for the application.
Significance:
With the weighty distinction of being called the next industrial revolution, 3D printing technologies is already altering many industrial and academic operations including changing models for future healthcare delivery in medicine and dentistry.
As an indicator of general indoor air quality in industrial facilities, the concentrations of total volatile organic compounds (TVOC) were determined in the workplaces of 37 industry sectors during the years of 2006–2011. For comparison, the TVOC levels in office-type workplaces were also determined. Based on the results, the TVOC target and guideline values are proposed for industrial workplaces. The geometric mean and median concentrations in the industrial workplaces were 778 and 845 µg/m3, respectively, while the 90th, 25th percentiles were, respectively, 6616 and 270 µg/m3. In the office-type environments, the geometric mean and median concentrations were 55 and 50 µg/m3, and the 90th and 25th percentiles were 230 and 27 µg/m3. Based on the measured TVOC distributions and the target values previously set, we propose a TVOC target value of 300 µg/m3 and guideline value of 3000 µg/m3 for the general indoor air in industrial workplaces. The concentration of 3000 µg/m3 could be achieved with reasonable measures by most industry sectors, but does not guarantee that the inhalation exposure to volatile organic compounds in the occupational environments is free from health concerns or perceived discomfort. Therefore, when reasonably achievable, a TVOC concentration close to or below the target value is recommended. This would make the TVOC levels in industrial facilities similar to those in the non-occupational indoor environments.
This is a cross-sectional review of biomarkers used in air pollution research from January 2009 through December 2012. After an initial keyword search in PubMed retrieving 426 articles, a comprehensive abstract review identified 54 articles of experimental design that used biomarkers of exposure or effect in human studies in the area of air pollution research during this specified time period. A thorough bibliographic search of the included articles retrieved an additional 65 articles meeting the inclusion criteria. This review presents these 119 studies and the 234 biomarkers employed in these air pollution research investigations. Data presented are 70 biomarkers of exposure with 54% relating to polycyclic aromatic hydrocarbons, 36% volatile organic carbons, and 10% classified as other. Of the 164 biomarkers of effect, 91 and 130 were used in investigating effects of short-term and chronic exposure, respectively. Results of biomarkers used in short-term exposure describe different lag times and pollutant components such as primary and secondary pollutants, and particle number associated with corresponding physiological mechanisms including airway inflammation, neuroinflammation, ocular, metabolic, early endothelial dysfunction, coagulation, atherosclerosis, autonomic nervous system, oxidative stress, and DNA damage. The review presents three different exposure scenarios of chronic, occupational, and extreme exposure scenarios (indoor cooking) with associated biomarker findings presented in three broad categories of (1) immune profile, (2) oxidative stress, and (3) DNA damage. This review offers a representation of the scope of data being explored by air pollution researchers through the use of biomarkers and has deliberately been restricted to this particular subject rather than an extensive or in-depth review. This article provides a contextualization of air pollution studies conducted with biomarkers in human subjects in given areas while also integrating this complex body of information to offer a useful review for investigators in this field of study.
Volatile organic compounds (VOCs) may be emitted from surfaces indoors leading to compromised air quality. This study scrutinized the influence of relative humidity (RH) on VOC concentrations in a building that had been subjected to water damage. While air samplings in a damp room at low RH (21-22 %) only revealed minor amounts of 2-ethylhexanol (3 μg/m(3)) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB, 8 μg/m(3)), measurements performed after a rapid increase of RH (to 58-75 %) revealed an increase in VOC concentrations which was 3-fold for 2-ethylhexanol and 2-fold for TXIB. Similar VOC emission patterns were found in laboratory analyses of moisture-affected and laboratory-contaminated building materials. This study demonstrates the importance of monitoring RH when sampling indoor air for VOCs in order to avoid misleading conclusions from the analytical results.
Objectives:
Thermoplastics may contain a wide range of additives and free monomers, which themselves may be hazardous substances. Laboratory studies have shown that the thermal decomposition products of common plastics can include a number of carcinogens and respiratory sensitizers, but very little information exists on the airborne contaminants generated during actual industrial processing. The aim of this work was to identify airborne emissions during thermal processing of plastics in real-life, practical applications.
Methods:
Static air sampling was conducted at 10 industrial premises carrying out compounding or a range of processes such as extrusion, blown film manufacture, vacuum thermoforming, injection moulding, blow moulding, and hot wire cutting. Plastics being processed included polyvinyl chloride, polythene, polypropylene, polyethylene terephthalate, and acrylonitrile-butadiene-styrene. At each site, static sampling for a wide range of contaminants was carried out at locations immediately adjacent to the prominent fume-generating processes.
Results:
The monitoring data indicated the presence of few carcinogens at extremely low concentrations, all less than 1% of their respective WEL (Workplace Exposure Limit). No respiratory sensitizers were detected at any sites.
Conclusions:
The low levels of process-related fume detected show that the control strategies, which employed mainly forced mechanical general ventilation and good process temperature control, were adequate to control the risks associated with exposure to process-related fume. This substantiates the advice given in the Health and Safety Executive's information sheet No 13, 'Controlling Fume During Plastics Processing', and its broad applicability in plastics processing in general.