Carbon Nanotubes: Probabilistic Approach for Occupational Risk Assessment

Abstract

In this study, the occupational risk assessment of carbon nanotubes (CNTs) was performed by means of a probabilistic approach. Chronic and subchronic inhalation exposure studies were retrieved during the hazard identification phase of the study. These studies were then used to obtain a guidance value (BMCh, expressed as a lognormal distribution with geometric mean ± geometric standard deviation = 10.0 ± 4.2 µg/m3) for occupational inhalation exposure to CNTs. An exposure scenario was selected from the scientific literature: three different work events (WEs) related to the production of conductive films were considered: (WE1) manufacturing of single walled carbon nanotubes films during normal operation using local exhaust ventilation (LEV); (WE2) manufacturing of SWCNT film without LEV; and (WE3) cleaning of one of the reactors. For each WE, a probability distribution function was applied, considering exposure expressed as mass concentration, as derived from three different measurement techniques. The ratio of the exposure and the BMCh distributions (i.e., the risk characterization ratio—RCR) was used to calculate the probability of occurrence of a relevant occupational risk. All the considered WEs indicated the presence of a risk (i.e., RCR distributions ≥ 1); however, only WE2 resulted in a statistically significant level of risk.

Occupational Exposure to Carbon Nanotubes and Carbon Nanofibres: More Than a Cobweb

“…A probabilistic approach has been recently suggested, in order to estimate the likelihood of risk for a selected occupational scenario and propose a realistic benchmark concentration (expressed as mass concentrations) for occupational exposure to CNTs [80]. Although pragmatic and useful, such an approach reveals its limitations when facing hazard heterogeneity and in predicting long-term health effects.…”

Safe nanomaterials: from their use, application, and disposal to regulations

“…217 Together with LCAs, another helpful tool is the RA which can be dened as «a quantitative and qualitative assessment of the risk involved to health and/or environment due to the presence 220 On the other hand, the EC bases the performance of NMs RA in the food industry and agriculture on the European Food Safety Authority documents 221 or in the procedures established by REACH. 7 Some of the most recent research papers consulted oriented to RA have different approaches ranging from graphic and probabilistic methods, [222][223][224] environmental studies using model organisms such as Daphnia Magna, Vibrio scheri, Chlorella sp. or Drosophila melanogaster, 225,226 occupational riskoriented studies 222,227 or the everyday use of RA and LCA.…”

Continuous Long-Term Exposure to Low Concentrations of MWCNTs Induces an Epithelial-Mesenchymal Transition in BEAS-2B Cells

“…The main exposure route for workers is inhalation by which CNTs can reach the most distal areas of the pulmonary system. Because of their density and size, they can reach deep into the lungs where the airway epithelium is the first line of contact with the inhaled materials [ 6 ].…”