Engineered carbonaceous nanomaterials manufacturers in the United States: workforce size, characteristics, and feasibility of epidemiologic studies.
ABSTRACT Toxicology studies suggest that carbon nanotube (CNT) exposures may cause adverse pulmonary effects. This study identified all US engineered carbonaceous nanomaterial (ECN) manufacturers, determined workforce size and growth, and characterized the materials produced to determine the feasibility of occupational ECN exposure studies.
Eligible companies were identified; information was assembled on the companies and nanomaterials they produced; and the workforce size, location, and growth were estimated.
Sixty-one companies manufacturing ECN in the United States were identified. These companies employed at least 620 workers; workforce growth was projected at 15% to 17% annually. Most companies produced or used CNT. Half the eligible companies provided information about material dimensions, quantities, synthesis methods, and worker exposure reduction strategies.
Industrywide exposure assessment studies appear feasible; however, cohort studies are likely infeasible because of the small, scattered workforce.
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ABSTRACT: RESEARCH SIGNIFICANCE: Toxicological evidence suggests the potential for a wide range of health effects, which could result from exposure to carbon nanotubes (CNTs) and carbon nanofibers (CNFs). The National Institute for Occupational Safety and Health (NIOSH) has proposed a recommended exposure limit (REL) for CNTs/CNFs at the respirable size fraction. The current literature is lacking exposure information, with few studies reporting results for personal breathing zone (PBZ) samples in occupational settings. To address this gap, exposure assessments were conducted at six representative sites identified as CNT/CNF primary or secondary manufacturers. Personal and area filter-based samples were collected for both the inhalable mass concentration and the respirable mass concentration of elemental carbon (EC) as well as CNT structure count analysis by transmission electron microscopy to assess exposures. When possible, full-shift PBZ samples were collected; area samples were collected on a task-based approach. The vast majority of samples collected in this study were below the proposed REL (7 μg m(-3)). Two of the three secondary manufacturers' surveyed found concentrations above the proposed REL. None of the samples collected at primary manufacturers were found to be above the REL. Visual and microscopy-based evidence of CNTs/CNFs were found at all sites, with the highest CNT/CNF structure counts being found in samples collected at secondary manufacturing sites. The statistical correlations between the filter-based samples for the mass concentration of EC and CNT structure counts were examined. A general trend was found with a P-value of 0.01 and a corresponding Pearson correlation coefficient of 0.44. CNT/CNF concentrations were above the proposed NIOSH REL for PBZ samples in two secondary manufacturing facilities that use these materials for commercial applications. These samples were collected during dry powder handling processes, such as mixing and weighing, using fairly large quantities of CNTs/CNFs.Annals of Occupational Hygiene 12/2011; 56(5):542-56. DOI:10.1093/annhyg/mer110 · 2.07 Impact Factor
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ABSTRACT: Nanotechnology presents the possibility of revolutionizing many aspects of our lives. People in many settings (academic, small and large industrial, and the general public in industrialized nations) are either developing or using engineered nanomaterials (ENMs) or ENM-containing products. However, our understanding of the occupational, health and safety aspects of ENMs is still in its formative stage. A survey of the literature indicates the available information is incomplete, many of the early findings have not been independently verified, and some may have been over-interpreted. This review describes ENMs briefly, their application, the ENM workforce, the major routes of human exposure, some examples of uptake and adverse effects, what little has been reported on occupational exposure assessment, and approaches to minimize exposure and health hazards. These latter approaches include engineering controls such as fume hoods and personal protective equipment. Results showing the effectiveness - or lack thereof - of some of these controls are also included. This review is presented in the context of the Risk Assessment/Risk Management framework, as a paradigm to systematically work through issues regarding human health hazards of ENMs. Examples are discussed of current knowledge of nanoscale materials for each component of the Risk Assessment/Risk Management framework. Given the notable lack of information, current recommendations to minimize exposure and hazards are largely based on common sense, knowledge by analogy to ultrafine material toxicity, and general health and safety recommendations. This review may serve as an overview for health and safety personnel, management, and ENM workers to establish and maintain a safe work environment. Small start-up companies and research institutions with limited personnel or expertise in nanotechnology health and safety issues may find this review particularly useful.Journal of Occupational Medicine and Toxicology 03/2011; 6:7. DOI:10.1186/1745-6673-6-7 · 1.23 Impact Factor
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ABSTRACT: The present paper deals with the applicability of biological monitoring to the assessment of exposure and possible effects deriving from exposure to engineered nanomaterials (NM). After establishing a conceptual framework in which human biomonitoring should be placed, the paper reviews the critical issues related to the unusual properties of NM affecting the implementation of biomonitoring activities for this new class of chemicals. Relying on the recent advances in the toxicogenomic, it is possible to assess whether specific biological pathways are activated or perturbed by specific NM. However, to evaluate if quantitative changes in these biomarkers can be used as indicators or predictors for toxicity in humans, validation on well characterised groups of exposed people is needed. At present, it appears more pragmatic to evolve NM-associated biomarker identification considering relevant biological responses found in environmental and occupational studies and assessing the early events associated with exposure to these NM. The battery of biochemical markers includes soluble molecules, antioxidant capacity, peroxidated lipids and carbonyl groups in serum proteins as a biomarkers of systemic inflammation and vascular adhesion molecules to assess endothelial activation/damage. Abnormalities in exhaled breath condensate chemistry reflecting intrinsic changes in the airway lining fluid and lung inflammation seem promising tools suitable for BM studies and are broadly discussed.Journal of Nanomaterials 01/2012; 2012(1687-4110). DOI:10.1155/2012/564121 · 1.61 Impact Factor