Nanomaterial exposure, toxicity, and impact on human health.

The use of engineered nanomaterials (ENM) has grown after the turn of the 21st century. Also, the production of ENM has globally grown, and exposure of workers especially via the lungs to ENM has increased. This review tackles with effects of ENM on workers' health because occupational environment is the main source of exposure to ENM. Assessment of exposure to ENM is demanding, and today there are no occupational exposure level (OEL) for ENM. This is partly due to challenges of such measurements, and in part to the unknown causality between ENM metrics and effects. There are also marked gaps in systematic knowledge on ENM hazards. Human health surveys of exposed workers, or human field studies have not identified specific effects of ENM linking them with a specific exposure. There is, however, a consensus that material characteristics such as size, and chemistry influence effects of ENM. Available data suggest that multiwalled carbon nanotubes (MWCNT) affect the immunological system and cause inflammation of the lungs, or signs of asthma whereas carbon nanofibers (CNF) may cause interstitial fibrosis. Metallic and metal oxide nanoparticles together with MWCNT induce genotoxicity, and a given type of MWCNT has been identified as a possible human carcinogen. Currently, lack of understanding of mechanisms of effects of ENM renders assessment of hazards and risks of ENM material-by-material a necessity. The so called "omics" approaches utilizing ENM-induced alterations in gene and protein expression may be useful in the development of a new paradigm for ENM hazard and risk assessment. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.