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Mikroplastik Kirliliği ve Tatlısu Ekosistemlerindeki Etkileri
Abstract
Günümüzde kullanılan birçok materyal; ucuz maliyeti, işlenme kolaylığı, dayanıklılığı ve elverişliliği gibi nedenlerle gerek ana hammadde gerekse yan ürün olarak yaygın bir şekilde plastik içermektedir. Bu yaygın kullanım, kaçınılmaz olarak küresel ölçekte toplam plastik üretimini ve buna bağlı olarak atık plastik miktarını gün geçtikçe attırmaktadır. Atık plastikler en nihayetinde doğaya karışarak, birçoğu doğada çözünmediği veya çok geç çözündüğü için, uzun süre mevcudiyet gösterebilmektedir. Bu mevcudiyet, beraberinde önemli sorunlar getirmektedir. Bu sorunların en önemlilerinden birisi ve günümüzde en çok üzerine yoğunlaşılanı; plastiklerin canlı yaşamına olan etkisidir. Sorun teşkil eden en önemli plastik gruplarından biri ise boyutları nedeniyle canlı vücuduna alınması ihtimali yüksek olan mikroplastiklerdir. Mikroplastikler, genel olarak 5 mm’den küçük olan plastikler olarak tanımlanmaktadır. Mikroplastikler, sucul ekosistemlere doğrudan katılabildiği gibi, büyük boyutlardaki plastiklerin doğal süreçler sonucunda parçalanarak dağılmasıyla da ortaya çıkabilmektedir. Bunlar çeşitli yollarla canlıların vücutlarına girerek birtakım fizyolojik ve kimyasal süreçlerle etkileşime girebilmektedir. Nispeten yeni sayılabilecek bu konuda literatürde hatırı sayılır düzeyde bilgi birikimi bulunsa da ilgilendirdiği birçok hususta genel geçer kanılara varabilmek için katedilmesi gereken uzun bir yol vardır. Buradan hareketle bu derleme makalede okuyucuya mevcut literatür verileri ışığında bugüne dek katedilen yolda elde edilen bilgilerin aktarılması ve mikroplastiklerin çevresel etkisini azaltmaya yönelik çalışmalar için ilgili otoritelerin dikkatinin çekilmesi amaçlanmıştır. Bu amaçlara ulaşmak için mikroplastiklerin tarihçesi, sınıflandırılması, kaynakları, doğaya karışması, yayılımı, canlılar tarafından alınımı, canlılara olan etkileri ve çevresel riskleri tartışılmıştır.
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Since the beginning of the 2010s, the number of investigations on microplastics in freshwater increased dramatically. However, almost no study aims at investigating the various sources and fate of microplastics in a catchment. This chapter aims at analyzing the various sources and fate of microplastics for an urban catchment and its hydrosystem (sewage, runoff, etc.). It presents the results obtained during a 3-year study of the Paris Megacity. Such a study required the development of appropriate sampling strategies for each compartment. It was highlighted that fibers are highly concentrated in the studied area, and therefore a focus in this category of microplastics was carried out. The atmospheric fallout exhibited important levels of fibers. However, at the scale of the Parisian agglomeration, wastewater treatment plant disposals and combined sewer overflows represent the major sources (number of fibers introduced per year) among the studied ones.
Synthetic polymers are one of the most significant pollutants in the aquatic environment. Most research focused on small plastic particles, so-called microplastics (particle size, 1–5,000 μm). Compared to macroplastics, the small size complicates their determination in environmental samples and demands for more sophisticated analytical approaches. The detection methods of microplastics reported in the past are highly diverse. This chapter summarizes different strategies for the sampling of water and sediment and sample treatments, including the separation of plastic particles and removal of natural debris that are necessary prior the identification of microplastics. Moreover, the techniques used for the identification of plastics particles are presented in this chapter.
The ubiquitous detection of microplastics in aquatic ecosystems promotes the concern for adverse impacts on freshwater ecosystems. The wide variety of material types, sizes, shapes, and physicochemical properties renders interactions with biota via multiple pathways probable. So far, our knowledge about the uptake and biological effects of microplastics comes from laboratory studies, applying simplified exposure regimes (e.g., one polymer and size, spherical shape, high concentrations) often with limited environmental relevance. However, the available data illustrates species- and material-related interactions and highlights that microplastics represent a multifaceted stressor. Particle-related toxicities will be driven by polymer type, size, and shape. Chemical toxicity is driven by the adsorption-desorption kinetics of additives and pollutants. In addition, microbial colonization, the formation of hetero-aggregates, and the evolutionary adaptations of the biological receptor further increase the complexity of microplastics as stressors. Therefore, the aim of this chapter is to synthesize and critically revisit these aspects based on the state of the science in freshwater research. Where unavailable we supplement this with data on marine biota. This provides an insight into the direction of future research. In this regard, the challenge is to understand the complex interactions of biota and plastic materials and to identify the toxicologically most relevant characteristics of the plethora of microplastics. Importantly, as the direct biological impacts of natural particles may be similar, future research needs to benchmark synthetic against natural materials. Finally, given the scale of the research question, we need a multidisciplinary approach to understand the role of microplastics in a multiple-particle world.
The accumulation of plastic debris in aquatic environments is one of the major but least studied human pressures on aquatic ecosystems. Besides the general waste burden in waterbodies, (micro)plastic debris gives rise to ecological and social problems. Related to marine ecosystems, these problems are already in the center of interest of science, policy, and public. The United Nations Environment Programme, for instance, drafted a joint report on “marine plastic debris and microplastics,” and the European Community included the issue into the European Marine Strategy Framework Directive, descriptor 10 “marine litter.”
In recent years, interest in the environmental occurrence and effects of microplastics (MPs) has shifted towards our inland waters, and in this chapter we provide an overview of the issues that may be of concern for freshwater environments. The term ‘contaminant of emerging concern’ does not only apply to chemical pollutants but to MPs as well because it has been detected ubiquitously in freshwater systems. The environmental release of MPs will occur from a wide variety of sources, including emissions from wastewater treatment plants and from the degradation of larger plastic debris items. Due to the chemical makeup of plastic materials, receiving environments are potentially exposed to a mixture of micro- and nano-sized particles, leached additives, and subsequent degradation products, which will become bioavailable for a range of biota. The ingestion of MPs by aquatic organisms has been demonstrated, but the long-term effects of continuous exposures are less well understood. Technological developments and changes in demographics will influence the types of MPs and environmental concentrations in the future, and it will be important to develop approaches to mitigate the input of synthetic polymers to freshwater ecosystems.
Concerns are being raised that microplastic pollution can have detrimental effects on the feeding of aquatic invertebrates, including zooplankton. Both small plastic fragments (microplastics, MPs) produced by degradation of larger plastic waste (secondary MPs; SMPs) and microscopic plastic spheres used in cosmetic products and industry (primary MPs; PMPs) are ubiquitously present in the environment. However, despite the fact that most environmental MPs consist of weathered plastic debris with irregular shape and broad size distribution, experimental studies of organism responses to MP exposure have largely used uniformly sized spherical PMPs. Therefore, effects observed for PMPs in such experiments may not be representative for MP-effects in situ. Moreover, invertebrate filter-feeders are generally well adapted to the presence of refractory material in seston, which questions the potential of MPs at environmentally relevant concentrations to measurably affect digestion in these organisms. Here, we compared responses to MPs (PMPs and SMPs) and naturally occurring particles (kaolin clay) using the cladoceran Daphnia magna as a model organism. We manipulated food levels (0.4 and 9 μg C mL-1) and MP or kaolin contribution to the feeding suspension (
The release of plastics into the environment has been identified as an important issue for some time. Recent publications have suggested that the degradation of plastic materials will result in the release of nano-sized plastic particles to the environment. Nanoparticle tracking analysis was applied to characterise the formation of nanoplastics during the degradation of a polystyrene (PS) disposable coffee cup lid. The results clearly show an increase in the formation of nanoplastics over time. After 56 days' exposure the concentration of nanoplastics in the PS sample was 1.26 × 108 particles/ml (average particles size 224 nm) compared to 0.41 × 108 particles/ml in the control.
The amount of plastics released to the environment in modern days has increased substantially since the development of modern plastics in the early 1900s. As a result, concerns have been raised by the public about the impact of plastics on nature and on, specifically, aquatic wildlife. Lately, much attention has been paid to macro- and micro-sized plastics and their impact on aquatic organisms. However, micro-sized plastics degrade subsequently into nano-sizes whereas nano-sized particles may be released directly into nature. Such particles have a different impact on aquatic organisms than larger pieces of plastic due to their small size, high surface curvature, and large surface area. This review describes the possible sources of nano-sized plastic, its distribution and behavior in nature, the impact of nano-sized plastic on the well-being of aquatic organisms, and the difference of impact between nano- and micro-sized particles. We also identify research areas which urgently need more attention and suggest experimental methods to obtain useful data.
Between 60% and 80% of all marine litter is plastic. Leachate from plastics has previously been shown to cause acute toxicity in the freshwater species Daphnia magna. Here, we present an initial screening of the marine environmental hazard properties of leachates from weathering plastics to the marine harpacticoid copepod [Crustacea] Nitocra spinipes. Twenty-one plastic products made of different polymeric materials were leached and irradiated with artificial sunlight. Eight of the twenty-one plastics (38%) produced leachates that caused acute toxicity. Differences in toxicity were seen for different plastic products, and depending on the duration of irradiation. There was no consistent trend in how toxicity of leachate from plastics changed as a function of irradiation time. Leachate from four plastics became significantly more toxic after irradiation, two became significantly less toxic and two did not change significantly. Analysis of leachates from polyvinyl chloride (PVC) by liquid chromatography coupled to a full-scan high-resolution mass spectrometer showed that the leachates were a mixture of substances, but did not show evidence of degradation of the polymer backbone. This screening study demonstrates that leachates from different plastics differ in toxicity to N. spinipes and that the toxicity varies under simulated weathering.
Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
Plastic litter is an environmental problem of great concern. Despite the magnitude of the plastic pollution in our water bodies there is still limited scientific understanding about the risk for the environment, particularly for microplastics. The apparent magnitude of the problem calls for quickly developing sound scientific guidance on the ecological risks of microplastics. We suggest future research into MP risks should be guided by lessons learned from the more advanced and better understood areas of (eco)toxicology of engineered nanoparticles and mixture toxicity. Relevant examples of advances in these two fields are provided to help accelerate the scientific learning curve within the relatively unexplored area of MP risk assessment. Finally, we advocate an expansion of the "vector effect" hypothesis in regards to microplastics risk to help focus research of MP environmental risk at different levels of biological and environmental organization. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
The development of biodegradable plastic mulch films for use in agriculture has been ongoing for decades. These films consist of mixtures of polymers with various additives. As a result, their physical and chemical properties differ from those of the pure polymers often used for in vitro enzymatic and microbial degradation studies, raising questions about the biodegradation capability of mulch films. Currently, standards exist for the biodegradation of plastics in composting conditions but not in soil. Biodegradation in soil or compost depends on a complex synergy of biological and abiotic degradative processes. This review discusses the physicochemical and structural properties of biodegradable plastic mulches, examines their potential for on-site decomposition in light of site-to-site variance due to environmental and biological conditions, and considers the potential for long-term effects on agroecosystem sustainability and functionality.
Background:
Synthetic microplastics (≤5-mm fragments) are emerging environmental contaminants that have been found to accumulate within coastal marine sediments worldwide. The ecological impacts and fate of microplastic debris are only beginning to be revealed, with previous research into these topics having primarily focused on higher organisms and/or pelagic environments. Despite recent research into plastic-associated microorganisms in seawater, the microbial colonization of microplastics in benthic habitats has not been studied. Therefore, we employed a 14-day microcosm experiment to investigate bacterial colonization of low-density polyethylene (LDPE) microplastics within three types of coastal marine sediment from Spurn Point, Humber Estuary, U.K.
Results:
Bacterial attachment onto LDPE within sediments was demonstrated by scanning electron microscopy and catalyzed reporter deposition fluorescence in situ hybridisation (CARD-FISH). Log-fold increases in the abundance of 16S rRNA genes from LDPE-associated bacteria occurred within 7 days with 16S rRNA gene numbers on LDPE surfaces differing significantly across sediment types, as shown by quantitative PCR. Terminal-restriction fragment length polymorphism (T-RFLP) analysis demonstrated rapid selection of LDPE-associated bacterial assemblages whose structure and composition differed significantly from those in surrounding sediments. Additionally, T-RFLP analysis revealed successional convergence of the LDPE-associated communities from the different sediments over the 14-day experiment. Sequencing of cloned 16S rRNA genes demonstrated that these communities were dominated after 14 days by the genera Arcobacter and Colwellia (totalling 84-93% of sequences). Attachment by Colwellia spp. onto LDPE within sediments was confirmed by CARD-FISH.
Conclusions:
These results demonstrate that bacteria within coastal marine sediments can rapidly colonize LDPE microplastics, with evidence for the successional formation of plastisphere-specific bacterial assemblages. Although the taxonomic compositions of these assemblages are likely to differ between marine sediments and the water column, both Arcobacter and Colwellia spp. have previously been affiliated with the degradation of hydrocarbon contaminants within low-temperature marine environments. Since hydrocarbon-degrading bacteria have also been discovered on plastic fragments in seawater, our data suggest that recruitment of hydrocarbonoclastic bacteria on microplastics is likely to represent a shared feature between both benthic and pelagic marine habitats.
Plastic film mulching has played an important role in Chinese agriculture due to its soil warming and moisture conservation effects. With the help of plastic film mulch technology, grain and cash crop yields have increased by 20–35% and 20–60%, respectively. The area of plastic film coverage in China reached approximately 20 million hectares, and the amount of plastic film used reached 1.25 million tons in 2011. While producing huge benefits, plastic film mulch technology has also brought on a series of pollution hazards. Large amounts of residual plastic film have detrimental effects on soil structure, water and nutrient transport and crop growth, thereby disrupting the agricultural environment and reducing crop production. To control pollution, the Chinese government urgently needs to elevate plastic film standards. Meanwhile, research and development of biodegradable mulch film and multi-functional mulch recovery machinery will help promote effective control and management of residual mulch pollution.
Background: While the use of plastic materials has generated huge societal benefits, the ‘plastic age’ comes with downsides: One issue of emerging concern is the accumulation of plastics in the aquatic environment. Here, so-called microplastics (MP), fragments smaller than 5 mm, are of special concern because they can be ingested throughout the food web more readily than larger particles. Focusing on freshwater MP, we briefly review the state of the science to identify gaps of knowledge and deduce research needs.
State of the science: Environmental scientists started investigating marine (micro)plastics in the early 2000s. Today, a wealth of studies demonstrates that MP have ubiquitously permeated the marine ecosystem, including the polar regions and the deep sea. MP ingestion has been documented for an increasing number of marine species. However, to date, only few studies investigate their biological effects.
The majority of marine plastics are considered to originate from land-based sources, including surface waters. Although they may be important transport pathways of MP, data from freshwater ecosystems is scarce. So far, only few studies provide evidence for the presence of MP in rivers and lakes. Data on MP uptake by freshwater invertebrates and fish is very limited.
Knowledge gaps: While the research on marine MP is more advanced, there are immense gaps of knowledge regarding freshwater MP. Data on their abundance is fragmentary for large and absent for small surface waters.Likewise, relevant sources and the environmental fate remain to be investigated. Data on the biological effects of MP in freshwater species is completely lacking. The accumulation of other freshwater contaminants on MP is of special interest because ingestion might increase the chemical exposure. Again, data is unavailable on this important issue.
Conclusions: MP represent freshwater contaminants of emerging concern. However, to assess the environmental risk associated with MP, comprehensive data on their abundance, fate, sources, and biological effects in freshwater ecosystems are needed. Establishing such data critically depends on a collaborative effort by environmental scientists from diverse disciplines (chemistry, hydrology, ecotoxicology, etc.) and, unsurprisingly, on the allocation of sufficient public funding.
There is now a plethora of polymer-based materials (PBMs) on the market, because of the increasing demand for cheaper consumable goods, and light-weight industrial materials. Each PBM constitutes a mixture of their representative polymer/sand their various chemical additives. The major polymer types are polyethylene, polypropylene,and polyvinyl chloride, with natural rubber and biodegradable polymers becoming increasingly more important. The most important additives are those that are biologically active, because to be effective such chemicals often have properties that make them resistant to photo-degradation and biodegradation. During their lifecycle,PBMs can be released into the environment form a variety of sources. The principal introduction routes being general littering, dumping of unwanted waste materials,migration from landfills and emission during refuse collection. Once in the environment,PBMs are primarily broken down by photo-degradation processes, but due to the complex chemical makeup of PBMs, receiving environments are potentially exposed to a mixture of macro-, meso-, and micro-size polymer fragments, leached additives, and subsequent degradation products. In environments where sunlight is absent (i.e., soils and the deep sea) degradation for most PBMs is minimal .The majority of literature to date that has addressed the environmental contamination or disposition of PBMs has focused on the marine environment. This is because the oceans are identified as the major sink for macro PBMs, where they are known to present a hazard to wildlife via entanglement and ingestion. The published literature has established the occurrence of microplastics in marine environment and beach sediments, but is inadequate as regards contamination of soils and freshwater sediments. The uptake of microplastics for a limited range of aquatic organisms has also been established, but there is a lack of information regarding soil organisms, and the long-term effects of microplastic uptake are also less well understood.There is currently a need to establish appropriate degradation test strategies consistent with realistic environmental conditions, because the complexity of environmental systems is lost when only one process (e.g., hydrolysis) is assessed in isolation. Enhanced methodologies are also needed to evaluate the impact of PBMs to soil and freshwater environments.
The accumulation of, and environmental hazards associated with, tire rubber and its disposal are major global concerns. The complex composition and structure of tire rubber and its additives make it highly resistant to natural degradation, but recently, microbial methods of detoxification and degradation of tire rubber have been developed. The polymers in tire rubber can be devulcanized by the activity of aerobic and anaerobic microbes and both the metabolic pathways and associated enzymes involved are becoming better known. Combining and adapting different rubber treatment processes could ultimately lead to more efficient ways of degrading and recycling tire rubber waste.
After a brief introduction to the various types of polymers in use and the size and impact of the polymer processing industry, this overview focuses on the most important processes for thermoplastic materials, namely extrusion and injection moulding. Single and twin screw extruders are used for melting and pumping of polymers and for die extrusion for the production of film, sheet, pipe, tubing, profiles and fibres. Injection moulding is the process used for the production of numerous parts, small and large, by injecting a molten polymer into mould cavities. Various problems associated with these processes are discussed. Other processes described include: calendering, compression moulding, rotational moulding, powder injection moulding and thixomoulding. The overview concludes with a brief discussion of current trends and future challenges faced by the polymer industry.
The growing use of plastics in agriculture has enabled farmers to increase their crop production. One major drawback of most
polymers used in agriculture is the problem with their disposal, following their useful life-time. Non-degradable polymers,
being resistive to degradation (depending on the polymer, additives, conditions etc) tend to accumulate as plastic waste,
creating a serious problem of plastic waste management. In cases such plastic waste ends-up in landfills or it is buried in
soil, questions are raised about their possible effects on the environment, whether they biodegrade at all, and if they do,
what is the rate of (bio?)degradation and what effect the products of (bio?)degradation have on the environment, including
the effects of the additives used. Possible degradation of agricultural plastic waste should not result in contamination of
the soil and pollution of the environment (including aesthetic pollution or problems with the agricultural products safety).
Ideally, a degradable polymer should be fully biodegradable leaving no harmful substances in the environment. Most experts
and acceptable standards define a fully biodegradable polymer as a polymer that is completely converted by microorganisms
to carbon dioxide, water, mineral and biomass, with no negative environmental impact or ecotoxicity. However, part of the
ongoing debate concerns the question of what is an acceptable period of time for the biodegradation to occur and how this
is measured. Many polymers that are claimed to be ‘biodegradable’ are in fact ‘bioerodable’, ‘hydrobiodegradable’, ‘photodegradable’,
controlled degradable or just partially biodegradable. This review paper attempts to delineate the definition of degradability
of polymers used in agriculture. Emphasis is placed on the controversial issues regarding biodegradability of some of these
polymers.
To more fully assess the toxicity of water-soluble fullerene (nC60), acute toxicity assays were performed on several environmentally relevant species. Included were the freshwater crustaceans Daphnia magna and Hyalella azteca, and a marine harpacticoid copepod, and two fish species, fathead minnow Pimephales promelas and Japanese medaka Oryzias latipes. The latter two species were used to assess sublethal effects of fullerene exposure by also assessing mRNA and protein expression in liver. Because prior studies found that both sonication and using tetrahydrofuran to solubilize fullerene increased the toxicity of nC60, the nC60 used in this study was prepared by stirring. For the invertebrate studies, nC60 could not be prepared at high enough concentration levels to cause 50% mortality (LC50) at 48 or 96 h. The maximum concentrations tested were 35 ppm for freshwater and 22.5 ppm for full-strength (35 ppt) seawater, since at higher concentrations the nC60 precipitated out of solution. Daphnia 21-day exposures resulted in a significant delay in molting and significantly reduced offspring production at 2.5 and 5 ppm nC60, which could possibly produce impacts at the population-level. For the fish, we found that neither the mRNA nor protein-expression levels of cytochrome P450 isozymes CYP1A, CYP2K1 and CYP2M1 were changed. The peroxisomal lipid transport protein PMP70 was significantly reduced in fathead minnow, but not medaka, indicating potential changes in acyl-CoA pathways.
The large global production of plastics and their presence everywhere in the society and the environment create a need for assessing chemical hazards and risks associated with plastic products. The aims of this study were to determine and compare the toxicity of leachates from plastic products made of five plastics types and to identify the class of compounds that is causing the toxicity.
Selected plastic types were those with the largest global annual production, that is, polypropylene, polyethylene, and polyvinyl chloride (PVC), or those composed of hazardous monomers (e.g., PVC, acrylonitrile-butadiene-styrene [ABS], and epoxy). Altogether 26 plastic products were leached in deionized water (3 days at 50°C), and the water phases were tested for acute toxicity to Daphnia magna. Initial Toxicity Identification Evaluations (C18 filtration and EDTA addition) were performed on six leachates.
For eleven leachates (42%) 48-h EC50s (i.e the concentration that causes effect in 50 percent of the test organisms) were below the highest test concentration, 250 g plastic/L. All leachates from plasticized PVC (5/5) and epoxy (5/5) products were toxic (48-h EC50s ranging from 2 to 235 g plastic/L). None of the leachates from polypropylene (5/5), ABS (5/5), and rigid PVC (1/1) products showed toxicity, but one of the five tested HDPE leachates was toxic (48-h EC50 17-24 g plastic/L). Toxicity Identification Evaluations indicated that mainly hydrophobic organics were causing the toxicity and that metals were the main cause for one leachate (metal release was also confirmed by chemical analysis).
Toxic chemicals leached even during the short-term leaching in water, mainly from plasticized PVC and epoxy products.
Urban littering is considered an important environmental and public issue globally. This problem is growing considerably within coastal communities of the southern region of South America. The goals of this study were to assess (1) the abundance and composition of urban litter; (2) the spatial and temporal variations of its abundance; and (3) the relationship between the abundance of litter and three anthropogenic variables (i.e. abundance of pedestrians, of parked vehicles, and of trash bins) in Mar del Plata, the most populated coastal city in Argentina. Eighty-eight transects, each covering 1425 m(2), were sampled along four sites from April 2008 to March 2009. Results showed 20,336 items (ca. 14 items per m(2)) of which cigarette butts (33%), papers (31%), and plastics (22%) were the most commonly littered items. Higher amounts of litter were found in an industrial area (city's harbor), while the abundance of litter appeared relatively even throughout the year. Redundancy analysis techniques indicated a high abundance of all three anthropogenic variables associated with the central business district area of the city and an area in close proximity to a major seaside resort, where cigarette butts and papers dominated. This is the first study that has examined spatial and temporal variations of urban litter in a high-density coastal city in Argentina. Our results showed that addressing the problems associated with urban litter must include intensive educational and advertising campaigns directed at pedestrians and owners of parked vehicles, but waste reduction, clean-up operations and law enforcement should be also considered.
This paper attempts to quantify the potential risks posed by engineered nanomaterials (ENMs) to the aquatic and terrestrial ecosystems from cosmetic-based nanoproducts. The predicted environmental concentrations (PEC) were modelled for the silver (nAg) and titanium dioxide (nTiO(2)) nanoparticles embedded in cosmetic nanoproducts. The Johannesburg Metropolitan City (JHB City), in South Africa, was used as the reference study area. A mathematical model was applied to compute the quantities of ENMs flows from the cosmetic nanoproducts into the JHB City aquatic and terrestrial ecosystems. The risk quotient (RQ) of the nanoscale materials were evaluated as a ratio of PEC to the predicted no effect concentrations (PNEC). RQ values showed wide variance due to factors like; the quantities of ENMs, the fate and pathways of ENMs in the aquatic and terrestrial ecosystems, efficiency of the wastewater treatment plants (WWTP) as well as the economic and demographic data for South Africa and Switzerland. For the aquatic environment, the PEC values of nAg ranged from 2.80 × 10(-3) to 6.19 × 10(-1) μg L(-1) whereas for nTiO(2) the values ranged from 2.7 0 × 10(-3) to 2.70 × 10(-1) μg L(-1) under the realistic dilution factor of 1 with the WWTP functioning at high removal efficiency regime. The RQ values in the aquatic ecosystems were mostly >1, indicating the potential risk of both nAg and nTiO(2) but <1 in the terrestrial ecosystems. Our results provide the first quantification of ENMs potential risk into the environment Johannesburg City in a developing country's natural and technical settings.
Plastic solid waste has become a serious problem when considering the disposal alternatives following the sequential hierarchy of sound solid waste management. This study was undertaken to assess the quantity and composition of household solid waste, especially plastic waste to identify opportunities for waste recycling. A 1-month survey of 130 households was carried out in Can Tho City, the capital city of the Mekong Delta region in southern Vietnam. Household solid waste was collected from each household and classified into ten physical categories; especially plastic waste was sorted into 22 subcategories. The average household solid waste generation rate was 281.27 g/cap/day. The compostable and recyclable shares respectively accounted for high percentage as 80.74% and 11%. Regarding plastic waste, the average plastic waste generation rate was 17.24 g/cap/day; plastic packaging and plastic containers dominated with the high percentage, 95.64% of plastic waste. Plastic shopping bags were especially identified as the major component, accounting for 45.72% of total plastic waste. Relevant factors such as household income and household size were found to have an existing correlation to plastic waste generation in detailed composition. The household habits and behaviors of plastic waste discharge and the aspects of environmental impacts and resource consumption for plastic waste disposal alternatives were also evaluated.
The safety of a polyester-polyurethane can coating has been assessed using a suite of complementary analytical methods to identify and estimate the concentrations of potential chemical migrants. The polyester was based on phthalic acids and aliphatic diols. The polyisocyanate cross-linking agent was 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl cyclohexane homopolymer (IPDI) blocked with methylethylketone oxime (MEKO) to make a one-part formulation. The overall migrate, obtained using solvent extraction of cured films, comprised almost completely of 12 cyclic and one linear polyester oligomer up to molecular weight 800 and containing up to six monomer units. These 13 oligomers covered a total of 28 isomeric forms. Other minor components detected were plasticisers and surfactants as well as impurities present in the starting materials. There was no detectable residue of either the blocked isocyanate (<0.01 microg/dm(2)) used as the starting substance or the unblocked isocyanate (<0.02 microg/dm(2)). The level of extractable IPDI was used as an indicator of the completeness of cure in experimental coatings. These studies revealed that there was an influence of time, temperature and catalyst content. Polymerisation was also influenced by the additives used and by the ageing of the wet coating formulation over several months. These studies allow parameters to be specified to ensure that commercial production coatings receive a full cure giving low migration characteristics.
This study investigated the formation and size distribution of microscopic plastic particles during the degradation of different plastic materials. Particle number concentrations in the size range 30 nm-60 μm were measured by nanoparticle tracking analysis (NTA) and Coulter Counter techniques. Each of the plastics used exhibited a measureable increase in the release of particles into the surrounding solution, with polystyrene (PS) and polylactic acid (PLA) generating the highest particle concentrations. After 112 d, particle concentrations ranged from 2147 particles ml(-1) in the control (C) to 92,465 particles ml(-1) for PS in the 2-60 μm size class; 1.2 × 10(5) particles ml(-1) (C) to 11.6 × 10(6) for PLA in the 0.6-18 μm size class; and 0.2 × 10(8) particles ml(-1) (C) to 6.4 × 10(8) particles ml(-1) for PS in the 30-2000 nm size class (84 d). A classification of samples based on principal component analysis showed a separation between the different plastic types, with PLA clustering individually in each of the three size classes. In addition, particle size distribution models were used to examine more closely the size distribution data generated by NTA. Overall, the results indicate that at the beginning of plastic weathering processes chain scission at the polymer surface causes many very small particles to be released into the surrounding solution and those concentrations may vary between plastic types.
In this work, we present for the first time undeniable evidence of nano-plastic occurrence due to solar light degradation of marine micro-plastics under controlled and environmentally representative conditions. As observed during our recent expedition (Expedition 7th Continent), plastic pollution will be one of the most challenging ecological threats for the next generation. Up to now, all studies have focused on the environmental and the economic impact of millimeter scale plastics. These plastics can be visualized, collected and studied. We are not aware of any studies reporting the possibilities of nano-plastics in marine water. Here, we developed for the first time a new solar reactor equipped with a nanoparticle detector to investigate the possibility of the formation of nano-plastics from millimeter scale plastics. With this system, correlated with electronic microscopy observations, we identified for the first time the presence of plastics at the nano-scale in water due to UV degradation. Based on our observations large fractal nano-plastic particles (i.e., >100 nm) are produced by UV light after the initial formation of the smallest nano-plastic particles (i.e., <100 nm). These unprecedented results show the new and unprecedented potential hazards of plastic waste at the nanoscale, which had not been taken into account previously.
Plastics have gained wide spread used because of their plasticity in form and function, and their benefits are wide ranging. The drawbacks to petrochemical plastics are that they are considered to be biologically inert. This in turn represents a waste management problem, especially for plastic materials with a short use phase. Presently, the development of biodegradable plastics as an alternative to petro-chemical plastics is seen as an important waste management option. Polyhydroxyalkanoates (PHAs) are a family of polyesters produced by the bacterial fermentation of sugars and lipids. PHAs have attracted commercial and academic interest because they are considered to be highly biodegradable. One of the most promising areas of application for PHAs is in the production of thin film materials for use as packaging materials. Presently, about 40% of the plastics produced worldwide are utilised for packaging purposes. The disposable nature of packaging materials makes the use of PHA plastics an attractive alternative. As such PHAs may help to solve some of the waste management issues associated with single use plastic items.
Quality and shelf life of food Physical and chemical interactions between plastics and food Organization of the book
Plastic debris is one of the most significant organic pollutants in the aquatic environment. Due to properties such as buoyancy and extreme durability, synthetic polymers are present in rivers, lakes and oceans and accumulate in sediments all over the world. However, freshwater sediments have attracted less attention than the investigation of sediments in marine ecosystems. For this reason, river shore sediments of the rivers Rhine and Main in the Rhine-Main area in Germany were analyzed. The sample locations comprised shore sediment of a large European river (Rhine) and a river characterized by industrial influence (Main) in areas with varying population sizes as well as sites in proximity to nature reserves. All sediments analyzed contained microplastic particles (<5mm) with mass fractions of up to 1 g kg-1 or 4000 particles kg-1 respectively. Analysis of the plastics by infrared spectroscopy showed a high abundance of polyethylene, polypropylene and polystyrene, which covered over 75% of all polymer types identified in the sediment. Short distance transport of plastic particles from the tributary to the main stream could be confirmed by the identification of pellets, which were separated from shore sediment samples of both rivers. This systematic study shows the emerging pollution of inland river sediments with microplastics and, as a consequence thereof, underlines the importance of rivers as transport vectors of microplastics into the ocean.
Plastic contamination is an increasing environmental problem in marine systems where it has spread globally to even the most remote habitats. Plastic pieces in smaller size scales, microplastics (particles <5mm), have reached high densities (e.g., 100 000 items per m3) in waters and sediments, and are interacting with organisms and the environment in a variety of ways. Early investigations of freshwater systems suggest microplastic presence and interactions are equally as far reaching as are being observed in marine systems. Microplastics are being detected in freshwaters of Europe, North America, and Asia, and the first organismal studies are finding that freshwater fauna across a range of feeding guilds ingest microplastics.
Plastic products can contain chemicals that are hazardous to human health and the environment. In this study, it was investigated if various plastic products emit hazardous chemical substances to water. Two leaching methods (batch and diffusion tests) were used and the leachates were tested for acute toxicity to Daphnia magna. Nine out of 32 tested plastic product leachates had Daphnia 48-h EC(50)s ranging from 5 to 80 g plastic material L(-1). For the remaining 23 products no effect on mobility was seen even at the highest test concentrations (70-100 g plastic material L(-1)). A compact disc (recordable) was the most toxic plastic product, but the toxicity was traced to the silver layer not the polycarbonate plastic material. The other products that displayed toxicity were made of either plasticized PVC (artificial leather, bath tub toy, inflatable bathing ring and table cloth) or polyurethane (artificial leather, floor coating and children's handbag). While the Toxicity Identification Evaluation (TIE) for compact discs using sodium thiosulfate addition showed that silver was causing the toxicity, the TIE for artificial leather using C18 cartridges showed that hydrophobic compounds were causing the toxicity. Acute toxicity tests of plastic product leachates were found to be useful for screening purposes for differentiating between toxic and non-toxic products.
Experiments were carried out with different Baltic Sea zooplankton taxa to scan their potential to ingest plastics. Mysid shrimps, copepods, cladocerans, rotifers, polychaete larvae and ciliates were exposed to 10 μm fluorescent polystyrene microspheres. These experiments showed ingestion of microspheres in all taxa studied. The highest percentage of individuals with ingested spheres was found in pelagic polychaete larvae, Marenzelleria spp. Experiments with the copepod Eurytemora affinis and the mysid shrimp Neomysis integer showed egestion of microspheres within 12 h. Food web transfer experiments were done by offering zooplankton labelled with ingested microspheres to mysid shrimps. Microscopy observations of mysid intestine showed the presence of zooplankton prey and microspheres after 3 h incubation. This study shows for the first time the potential of plastic microparticle transfer via planktonic organisms from one trophic level (mesozooplankton) to a higher level (macrozooplankton). The impacts of plastic transfer and possible accumulation in the food web need further investigations.
Discrimination of inert and nutritive particles was investigated in five crustacean zooplankton species. The two particle
types were represented by polystyrene beads and cultured algae respectively. The animals were offered combinations of beads
and a 14C-labelled alga of equal size. Four combinations of different sizes were used (2,6, 11 and 19 μm). Bosmina coregoni strongly discriminated against the 11 and 19 μm beads, while particles of the two smallest sizes were ingested non-selectively
within combinations. A selection against beads of all sizes was observed in Eudiaptomus gracilis although less intensively in the case of 2 and 6 μm particles. Daphnia cucullata, Chydorus sphæricus and Diaphanosoma brachyurum exhibited, on average, similar filtering rates for corresponding particles in the three smallest size classes but preferred
the alga over the 19 μm bead. The two or three smaller sizes of beads may be used to assess filtering rates for similarly
sized real food items. However, an uncritical use of this technique may be hazardous.
Following use polymer materials may be released to the natural environment distributed to various environmental compartments and may undergo a variety of mechanical and chemical weathering processes. This study characterised the degradation of a latex polymer of different thicknesses under a range of environmental conditions in outdoor microcosms. Samples were immersed in either demineralised water, artificial freshwater and marine water media and exposed for a period of 200-250days with exposure starting at different times of the year. Effects of pH, agitation and the exclusion of light on degradation were also studied. At the end of the exposure period, recovery of polymer material≥1.6μm ranged from a low of 22.04% (±16.35, for the freshwater treatment at pH5.5) to a high of 97.73% (±0.38, for the exclusion of light treatment). The disappearance of the bulk material corresponded to an increase in nanoparticles and dissolved organic material in the test media. Modelled degradation kinetics were characterised by multi-phasic degradation patterns and the results indicated degradation rate is affected by light intensity and polymer thickness. Mass balance analysis indicates that losses of volatile materials to the air compartment may also be occurring.
It has been speculated that marine microplastics may cause negative effects on benthic marine organisms and increase bioaccumulation of persistent organic pollutants (POPs). Here, we provide the first controlled study of plastic effects on benthic organisms including transfer of POPs. The effects of polystyrene (PS) microplastic on survival, activity, and bodyweight as well as the transfer of 19 polychlorinated biphenyls (PCBs), were assessed in bioassays with Arenicola marina (L.). PS was pre-equilibrated in natively contaminated sediment. A positive relation was observed between microplastic concentration in the sediment and both uptake of plastic particles and weight loss by A. marina. Furthermore, a reduction in feeding activity was observed at a PS dose of 7.4% dry weight (DW). A low PS dose of 0.074% increased bioaccumulation of PCBs by a factor 1.1 - 3.6, an effect that was significant for ΣPCBs and several individual congeners. At higher doses, bioaccumulation decreased compared to the low dose, which however, was only significant for PCB105. PS has statistically significant effects on the organisms' fitness and bioaccumulation, but the magnitude of the effects was not high. This may be different for sites with different plastic concentrations, or plastics with a higher affinity for POPs.
A test protocol has been developed that contains a suite of complementary analytical methods to identify and estimate the concentrations of potential chemical migrants in polymeric coatings applied to metal substrates. The capabilities of these techniques (FT-IR, overall migration, headspace GC-MS, GC-MS, and LC-TOF-MS) have been tested for a variety of polymeric coatings, and the results for one particular coating, an epoxy phenolic, are described as an example. The example provided shows both the power and the limitations of current analytical techniques in the evaluation of the total migrate from food contact materials.
Experimental Determination of Polymer/Liquid Partition CoefficientsThermodynamics of Partition Coefficients Equilibrium Between Different Phases in Ideal Solutions Partitioning in Ideal Solutions: Nernst's LawEquilibrium Between Different Phases in Nonideal Solutions Partition Coefficients for Nonideal SolutionsPartition Coefficients for Systems with PolymersRelationship Between Partition Coefficients and Solubility CoefficientsEstimation of Partition Coefficients Between Polymers and Liquids Additive Molecular PropertiesEstimation of Partition Coefficients Using QSAR and QSPRGroup-Contribution Thermodynamic Polymer Partition Coefficient Estimation Methods Estimation of Partition Coefficients Using RSTEstimation of Partition Coefficients Using UNIFACEstimation of Partition Coefficients Using Group-Contribution Flory Equation-of-StateEstimation of Partition Coefficients Using Elbro Free Volume ModelComparison of Thermodynamic Group-Contribution Partition Coefficient Estimation MethodsVapor Pressure Index Partition Coefficient Estimation Method Examples of Vapor Pressure Index ValuesReferences Equilibrium Between Different Phases in Ideal Solutions Partitioning in Ideal Solutions: Nernst's LawEquilibrium Between Different Phases in Nonideal Solutions Partition Coefficients for Nonideal SolutionsPartition Coefficients for Systems with PolymersRelationship Between Partition Coefficients and Solubility Coefficients Partitioning in Ideal Solutions: Nernst's Law Partition Coefficients for Nonideal Solutions Additive Molecular PropertiesEstimation of Partition Coefficients Using QSAR and QSPRGroup-Contribution Thermodynamic Polymer Partition Coefficient Estimation Methods Estimation of Partition Coefficients Using RSTEstimation of Partition Coefficients Using UNIFACEstimation of Partition Coefficients Using Group-Contribution Flory Equation-of-StateEstimation of Partition Coefficients Using Elbro Free Volume ModelComparison of Thermodynamic Group-Contribution Partition Coefficient Estimation Methods
Vapor Pressure Index Partition Coefficient Estimation Method Examples of Vapor Pressure Index Values Estimation of Partition Coefficients Using RSTEstimation of Partition Coefficients Using UNIFACEstimation of Partition Coefficients Using Group-Contribution Flory Equation-of-StateEstimation of Partition Coefficients Using Elbro Free Volume ModelComparison of Thermodynamic Group-Contribution Partition Coefficient Estimation Methods Examples of Vapor Pressure Index Values
Resistivity of plastic litter to chemical weathering, mechanical erosion, and biological degradation poses a critical environmental
threat. Plastic debris has increased in abundance over the past several decades along shorelines and at sea, where organisms
mistake small particles including plastic pellets as a potential food supply. These pellets have been shown to adsorb persistent
organic pollutants such as PCBs, which may endanger the organism and become ingested higher in the food chain. Although several
studies have been conducted to determine the amount and effects of plastics pollution in marine environments, relatively little
is known concerning fresh water plastics pollution. This study represents the first detailed examination of the distribution,
types, and physical and chemical degradation processes of plastic particles in a fresh water setting. In conducting field
surveys along the shoreline of Lake Huron, Canada, we were able to ascertain that the total number of pellets over multiple
sampling localities comprise 94% of plastic debris. The majority of the pellets were found proximal to an industrial sector
along the southeastern margin of the lake and their abundance steadily decreased northward, following the dominant lake current
patterns. Laboratory analyses using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy indicate
predominant mechanical abrasion textures, including grooves, gauges, pits, and flakes, and less common chemical weathering
features such as linear and crescentic fractures that developed from shrinkage during subaerial exposure. The predominant
type of plastic, polyethylene, appears to be much more resistant to chemical weathering than polypropylene, as indicated by
oxidation peaks on FTIR spectra suggesting that polypropylene degrades more readily under natural conditions on freshwater
beaches.
KeywordsPlastics pollution–Plastic pellets–Fresh water beaches–Lake Huron–SEM–FTIR
Over 24 million plastic bags are consumed in Kenya monthly. More than half of the bags end up in the solid waste stream. Plastic bags now constitute the biggest challenge to solid waste management in Nairobi, the capital of Kenya and home to three million people. As a result, plastic bag waste has attracted great political and public attention, especially because the waste has myriad unique environmental problems. This paper seeks to unravel the problem of plastic bag waste in Nairobi through an urban political ecological perspective. Urban political ecology has done much to excavate economic, political, and cultural processes, as well as ecological dynamics that create and re-create urban environments. Little has been done in this context with respect to urban solid waste problems, with the exception of urban political ecology of environmental justice. However, research done within the context of urban political ecology of environmental justice has mainly focused on solid waste problems in the Western World, particularly USA. Drawing on research conducted in Nairobi, as well literature on business and politics, and solid waste management in Kenya, this paper examines the nature of plastic bag waste problem, its political–economic roots and implications for environmental justice.
A review of degradable plastics technology has revealed that several effective copolymer and additive methods are used commercially for photodegradable plastics. However, it was found that all commercial packaging plastics are not biodegradable; all of them because their molecular weights are too high and their structures are too rigid for assimilation by organisms, and most of them also because they have substituents which prevent biodegradation via the enzymatic fatty acid oxidation mechanism. Linear polyethylene is the only commercial packaging plastic with potential for biodegradation when its molecular weight has been reduced drastically by photodegradation.Degradable plastics are not a satisfactory solution to the problems of municipal solid waste. For those problems, multiple approaches need to be used, including especially recycling and incineration.
Plastic debris <1 mm (defined here as microplastic) is accumulating in marine habitats. Ingestion of microplastic provides a potential pathway for the transfer of pollutants, monomers, and plastic-additives to organisms with uncertain consequences for their health. Here, we show that microplastic contaminates the shorelines at 18 sites worldwide representing six continents from the poles to the equator, with more material in densely populated areas, but no clear relationship between the abundance of miocroplastics and the mean size-distribution of natural particulates. An important source of microplastic appears to be through sewage contaminated by fibers from washing clothes. Forensic evaluation of microplastic from sediments showed that the proportions of polyester and acrylic fibers used in clothing resembled those found in habitats that receive sewage-discharges and sewage-effluent itself. Experiments sampling wastewater from domestic washing machines demonstrated that a single garment can produce >1900 fibers per wash. This suggests that a large proportion of microplastic fibers found in the marine environment may be derived from sewage as a consequence of washing of clothes. As the human population grows and people use more synthetic textiles, contamination of habitats and animals by microplastic is likely to increase.
This review discusses the mechanisms of generation and potential impacts of microplastics in the ocean environment. Weathering degradation of plastics on the beaches results in their surface embrittlement and microcracking, yielding microparticles that are carried into water by wind or wave action. Unlike inorganic fines present in sea water, microplastics concentrate persistent organic pollutants (POPs) by partition. The relevant distribution coefficients for common POPs are several orders of magnitude in favour of the plastic medium. Consequently, the microparticles laden with high levels of POPs can be ingested by marine biota. Bioavailability and the efficiency of transfer of the ingested POPs across trophic levels are not known and the potential damage posed by these to the marine ecosystem has yet to be quantified and modelled. Given the increasing levels of plastic pollution of the oceans it is important to better understand the impact of microplastics in the ocean food web.
The concern over the adverse effects of nanomaterials on humans has lead to an extensive research on the fate of nanoparticles in biological systems. However, unique properties of engineered nanomaterials yield many technical challenges which impede nanotoxicity studies. Some of these challenges are: interference of nanoparticles with in vitro toxicity assays, dissolution, studying cellular uptake and visualization, proper characterization, agglomeration etc. In the present study, zinc oxide (ZnO) nanoparticles were characterized for their size by dynamic light scattering which revealed their monodisperse nature. The cellular uptake of ZnO nanoparticles was analysed by flow cytometry. A significant increase in the percentage intensity of side scattering of cells treated with nanoparticles was observed as compared to the granularity of control cells. Further, the role of dissolution was evaluated by exposing cells to ZnCl2 at an equimolar dose of released zinc. No decrease in the cell viability was observed suggesting minimal role of dissolution in ZnO nanoparticle induced toxicity.
Engineered nanomaterials (ENM) are already used in many products and consequently released into environmental compartments. In this study, we calculated predicted environmental concentrations (PEC) based on a probabilistic material flow analysis from a life-cycle perspective of ENM-containing products. We modeled nano-TiO(2), nano-ZnO, nano-Ag, carbon nanotubes (CNT), and fullerenes for the U.S., Europe and Switzerland. The environmental concentrations were calculated as probabilistic density functions and were compared to data from ecotoxicological studies. The simulated modes (most frequent values) range from 0.003 ng L(-1) (fullerenes) to 21 ng L(-1) (nano-TiO(2)) for surface waters and from 4 ng L(-1) (fullerenes) to 4 microg L(-1) (nano-TiO(2)) for sewage treatment effluents. For Europe and the U.S., the annual increase of ENMs on sludge-treated soil ranges from 1 ng kg(-1) for fullerenes to 89 microg kg(-1) for nano-TiO(2). The results of this study indicate that risks to aquatic organisms may currently emanate from nano-Ag, nano-TiO(2), and nano-ZnO in sewage treatment effluents for all considered regions and for nano-Ag in surface waters. For the other environmental compartments for which ecotoxicological data were available, no risks to organisms are presently expected.
Purpose:
To study the uptake of biodegradable microparticles in Caco-2 cells.
Methods:
Biodegradable microparticles of polylactic polyglycolic acid co-polymer (PLGA 50:50) of mean diameters 0.1 micron, 1 micron, and 10 microns containing bovine serum albumin as a model protein and 6-coumarin as a fluorescent marker were formulated by a multiple emulsion technique. The Caco-2 cell monolayers were incubated with each diameter microparticles (100 micrograms/ml) for two hours. The microparticle uptake in Caco-2 cells was studied by confocal microscopy and also by quantitating the 6-coumarin content of the microparticles taken up by the cells. The effects of microparticle concentration, and incubation time and temperature on microparticle cell uptake were also studied.
Results:
The study demonstrated that the Caco-2 cell microparticle uptake significantly depends upon the microparticle diameter. The 0.1 micron diameter microparticles had 2.5 fold greater uptake on the weight basis than the 1 micron and 6 fold greater than the 10 microns diameter microparticles. Similarly in terms of number the uptake of 0.1 micron diameter microparticles was 2.7 x 10(3) fold greater than the 1 micron and 6.7 x 10(6) greater than the 10 microns diameter microparticles. The efficiency of uptake of 0.1 micron diameter microparticles at 100 micrograms/ml concentration was 41% compared to 15% and 6% for the 1 micron and the 10 microns diameter microparticles, respectively. The Caco-2 cell microparticle (0.1 micron) uptake increased with concentration in the range of 100 micrograms/ml to 500 micrograms/ml which then reached a plateau at higher concentration. The uptake of microparticles increased with incubation time, reaching a steady state at two hours. The uptake was greater at an incubation temperature of 37 degrees C compared to at 4 degrees C.
Conclusions:
The Caco-2 cell microparticle uptake was microparticle diameter, concentration, and incubation time and temperature dependent. The small diameter microparticles (0.1 micron) had significantly greater uptake compared to larger diameter microparticles. The results thus suggest that the mechanism of uptake of microparticles in Caco-2 cell is particle diameter dependent. Caco-2 cells are used as an in vitro model for gastrointestinal uptake, and therefore the results obtained in these studies could be of significant importance in optimizing the microparticle-based oral drug delivery systems.