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 strate-gies. The global aim of this study was to carry out a review of the state-of-the-science of ENMs occupational exposureassessment, with particular concern on the main problems related to ENPs exposure assessment. Original articles andreviews in principal databases of scientific literature were included in this paper; grey literature (released by qualifiedregulatory agencies and scientific organizations) was also taken into consideration. The paper discusses in particular themain problems found in ENPs exposure assessment, which have been generally identified in: (i) the choice of a properdosimetric for exposure assessment, (ii) the lack of adequate and reliable measurement techniques, (iii) the need of a har-monized monitoring strategy, (iv) the need of an effective method for the distinction of ENPs from background particlesand (v) the difficulties to compare ENPs exposure data with proper Occupational Exposure Limits. On the basis of theconsidered existing approaches, some key issues related to exposure assessment strategies, derived from direct on-fieldexposure are then discussed, as well as some identified priorities in the field of ENPs exposure assessment. In conclu-sion, most of the existing techniques and strategies for occupational exposure assessment to ENPs and ENMs requireadjustment, and significant methodological gaps need to be reduced. The rational use of risk management strategies andthe application of specifically-developed Occupational Exposure Limits are crucial to mitigate the risk posed for ENPs-exposed workers. The development and harmonization of appropriate exposure assessment strategies and techniquesand risk management approaches represent an essential step toward developing health and safety standards for ENPs.