Carbon Nanotubes: Probabilistic Approach for Occupational Risk Assessment.

Andrea Spinazzè,Giacomo Fanti,Davide Campagnolo,Marta Keller,Sabrina Rovelli,Andrea Cattaneo,Francesca Borghi,Carolina Zellino,Domenico M Cavallo

doi:10.3390/nano11020409

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.

Highlights

Reliable procedures for risk assessment (RA) need to be constantly implemented to evaluate the possible health impacts of engineered nanomaterials (NMs)
Starting from this review study, recent studies from peer-reviewed literature regarding occupational exposure assessments for carbon nanotubes (CNTs) were selected for the present study
Many studies have been conducted on exposure to CNTs, there are still many uncertainties and gaps related to the identification of the hazard in all its phases, and further research is required [8,14]

Summary

Introduction

Reliable procedures for risk assessment (RA) need to be constantly implemented to evaluate the possible health impacts of engineered nanomaterials (NMs). Among the major limitations concerns the availability of reliable information on NM to properly set the hazard assessment (i.e., hazard identification and dose–response relationship evaluation) and the exposure assessment phases of the RA [1,3]. The aim of the present study is to apply a probabilistic approach in a case study, to perform a risk assessment for an NM in selected occupational settings. The classical four steps in the RA process (1.) hazard identification, (2.) dose–response assessment, (3.). The same approach for occupational RA of NMs was firstly suggested by Tsang et al [4] for titanium dioxide nanoparticles and later applied by Spinazzè et al [5] for graphene nanoplatelets.

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Conclusion