Engineered Nano Materials: Why is it so difficult to determine potential public health concerns?

Engineered Nano Materials (ENMs) are widely used in the US and a lot of resources are devoted to researching and developing new applications. Although ENMs are common ingredients in consumer products, such as sunscreens, there is a lack of data that allows the robust assessment and management of health risks associated with this class of materials. After a brief introduction to ENMs and the implications of working at the nano-scale, the lifecycle of a hypothetical nanoparticle is used to illustrate knowledge gaps for assessing exposures to workers, the general population and environmental impacts (environmental fate). The steps associated with conducting a human health risk assessment are used to identify areas of uncertainty in evaluating public health impacts of ENMs: hazard identification (lack of established sampling and analytical methods for environmental media and biological specimen, how to identify and quantify unknown ENMs); dose-response (how to measure dose, which chronic and acute toxicity endpoints to study, scarcity of toxicological data available for most ENMs, in vitro vs. in vivo studies); exposure assessment (routes of exposure, no knowledge of location or number of workers exposed, exposures from presence in consumer products); and risk characterization (assessing cancer and non-cancer risks, developmental and reproductive toxicity). The current risk management process for ENMs is based on very limited information and can only be framed in very general terms (Safety Data Sheets, NIOSH guidelines).