Integrated approach for the assessment of exposure to and effects of nanomaterials in work environments

E. Bergamaschi | Department of Public Health and Pediatric Sciences, University of Turin, Italy

Introduction. The rapid spread of nanomaterials (NMs) across various industrial sectors has led to an increasing number of potentially exposed workers, but this has not been accompanied by the development of knowledge about their possible long-term health effects. Several studies have highlighted subclinical effects in worker groups, but due to their exploratory nature, small sample sizes, the absence of a control group, and poor exposure characterization, it was not possible to establish robust causal relationships between exposure and these effects.

Objectives and Methods. To go beyond the application of a mere precautionary principle, an integrated approach is needed that proactively links exposure to early biological effects, allowing for the implementation of effective preventive measures. This approach requires a multi-stage exposure assessment using the appropriate tools and metrics recommended by expert groups,¹ and the evaluation of exposure and effect biomarkers determined in biological matrices collected using non-invasive methods.² This holistic strategy has been pursued and implemented by some research projects, such as NanoExplore,³ and by the INAIL, contributing to the development of standardized methodologies and a harmonized protocol applied to case studies or specific occupational scenarios.

Results and Conclusions. Exposure assessment can currently rely on a multiparametric approach that uses direct monitoring tools (e.g., scanning mobility particle sizer, condensation particle counter), which allow the identification of exposure peaks related to specific tasks or events. These, when combined with transmission electron microscopy or scanning electron microscopy with microanalysis, improve the characterization of exposure. The Nanoparticle Emission Assessment Technique, developed by the National Institute for Occupational Safety and Health, provides a valuable sampling protocol for assessing the release of NMs at workplace. In the nanoExplore Project, changes in effect biomarkers were correlated with more appropriate metrics, such as particle number concentration (PNC), size distribution, or lung-deposited surface area (LDSA). The study have allowed for the identification of positive dose-response relationships between exposure to NMs and biomarkers of inflammation, oxidative stress, or fibrogenesis in exhaled breath condensate (EBC), and between PNC or LDSA and biomarkers and respiratory functional effects.³ Finally, the relationship between an increase in airborne PNC and NM deposition in the respiratory tract, measured in EBC using the nanoparticle tracking analysis technique, was estimated. Such an integrated strategy allows for the definition of causal relationships between exposure and early effects and the estimation of dose-response relationships, representing a paradigm shift in identifying threshold values to guide risk assessment and the definition of safe exposure levels. The adoption of standardized protocols also allows for the creation of a worker registry useful for conducting prospective epidemiological studies in specific occupational settings.