Engineered nanomaterials: current status of occupational exposure assessment.
An increasing number of studies are indicating that the health risk deriving from exposure to engineered nanomaterials (ENMs) and nanoparticles (ENPs) is not adequately addressed by conventional exposure evaluation methods and strategies. The global aim of this study was to carry out a review of the state-of-the-science of ENMs occupational exposure assessment, with particular concern on the main problems related to ENPs exposure assessment. Original articles and reviews in principal databases of scientific literature were included in this paper; grey literature (released by qualified regulatory agencies and scientific organizations) was also taken into consideration. The paper discusses in particular the main problems found in ENPs exposure assessment, which have been generally identified in: (i) the choice of a proper dosimetric for exposure assessment, (ii) the lack of adequate and reliable measurement techniques, (iii) the need of a harmonized monitoring strategy, (iv) the need of an effective method for the distinction of ENPs from background particles and (v) the difficulties to compare ENPs exposure data with proper Occupational Exposure Limits. On the basis of the considered existing approaches, some key issues related to exposure assessment strategies, derived from direct on-field exposure are then discussed, as well as some identified priorities in the field of ENPs exposure assessment. In conclusion, most of the existing techniques and strategies for occupational exposure assessment to ENPs and ENMs require adjustment, and significant methodological gaps need to be reduced. The rational use of risk management strategies and the application of specifically-developed Occupational Exposure Limits are crucial to mitigate the risk posed for ENP-exposed workers. The development and harmonization of appropriate exposure assessment strategies and techniques and risk management approaches represent an essential step toward developing health and safety standards for ENP.
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