Lessons from air pollution epidemiology for studies of engineered nanomaterials.

Objectives: This article discusses evidence from epidemiological studies on air pollution for assessing engineered nano-sized particles in workplace environments. Methods: Results from epidemiological studies on health effects of fine and ultrafine particles are summarized. These findings are applied to workplaces exposed to engineered nanoparticles. Results: Ultrafine or nano-sized particles smaller than 100 nm represent potential health hazards. Because of their short half-lives in ambient air and their large spatial variability, individual exposures in population-based studies are likely to be misclassified. Conclusions: Studies of health effects of nanoparticles in occupational settings seem mandated for adequate worker protection but face several challenges, including exposure quantification and adequate confounder characterization. Inclusion of personal measurements of ultrafine particles in future studies will allow exploiting the full scale of temporal-spatial variation of both ambient and engineered nanoparticles