Management bezpečnosti nanočástic s ohledem na bezpečnost práce

Abstract

Nanomaterials (NMs) and their applications have the potential to significantly improve the quality of life as well as to contribute to solving the main challenges of today's society. However, the same properties that render NMs unique and beneficial could cause their enhanced or unexpected toxicity. The motivation for this thesis was to contribute to the protection of workers in nanotechnologies as they may be in a higher risk of potential adverse effects of NMs due to prolonged regular exposure and high exposure concentrations. Analysis of the applicability of the traditional chemical risk assessment approach for NMs revealed high levels of uncertainty in both hazard characterization and exposure assessment due to the lack of relevant standardized methods and reliable data. The experimental part of the thesis is focused on evaluation of known mechanisms of NMs toxicity as well as unresolved toxicological issues that were detected in the theoretical part: inconsistent experimental data, relationship between physico-chemical properties and toxicity of NMs, specific toxic effects of NMs (mainly interactions of NMs with the immune system) and methods for their identification. Theoretical findings and practical experience with toxicity testing of NMs were utilized to prepare a proposal of the NM risk management for occupational settings. Control Banding (CB), a qualitative approach, was selected as a suitable risk management tool with regard to the detected high uncertainties. CB categorizes hazard and exposure into different levels, referred to as bands. The combination of the hazard and exposure bands results into a risk band determining the necessity to implement control and regulatory measures. The available CB tools and their applicability for the occupational NM risk management were reviewed. Subsequently, a scheme for the selection of an optimal tool for particular NMs and specific exposure conditions was prepared. For more accurate hazard categorization, a set of in vitro toxicological assays enabling screening evaluation of potential toxic effects of NMs was proposed. The selected assays evaluate four endpoints covering basic toxic effects of substances (cytotoxicity, genotoxicity), as well as known non-specific mechanisms of toxicity typical for NMs (oxidative stress, inflammation). The testing battery can be used for the comparison of toxicity of NMs with different physico-chemical properties and to prioritize and select less toxic NMs in an early phase of their development. The proposed NM risk management strategy is intended to assist small and medium-sized enterprises to implement adequate measures to ensure the employee safety.