Moving toward exposure and risk evaluation of nanomaterials: challenges and future directions.

Nanotechnology, the commercial development of engineered nanomaterials, promises breakthrough innovations by enhancing the performance of existing consumer products and enabling development of new devices, architectures, and applications. Although these materials and applications are being developed at an explosive pace, a fundamental understanding of any potential human health and environmental risks resulting from exposure throughout the lifecycle of these materials has not advanced as rapidly. Past experience has demonstrated that successful introduction of a new technology occurs more readily if it is precipitated by a robust appreciation for any inherent risks associated with the technology. Such understanding allows the timely development of occupational and consumer exposure standards that might be needed to protect human health and the environment. Although risk is recognized as the product of hazard and exposure, too often exposure patterns are poorly characterized, and risk is based primarily or exclusively on the hazard characterization. The extent of exposure to nanomaterials in currently available commercial products is relatively unknown. Given the number of commercial products that claim to contain engineered nanomaterials, it is possible that human and environmental exposure to these materials is widespread. This paper is intended to highlight the importance of exposure assessment for determining the potential risks of nanomaterials. In essence, this is a call to action to the community of exposure scientists, toxicologists, and risk assessors to develop, consider, and incorporate requisite exposure information in the risk assessment of nanomaterials. Without an integrated approach, it will be difficult to meaningfully assess the risks of nanomaterials, realize their potential benefits, and foster their sustainable development.