Medical Surveillance for Nanomaterials

Scientific uncertainties regarding the potential adverse health effects associated with occupational exposure to nanomaterials pose a challenge to the design and implementation of workplace medical surveillance. Preliminary reports in experimental animals suggest that compared to larger sized particles, nano-sized particles of the same compounds or elements may have different toxicokinetic and toxicodynamic profiles. In particular, current permissible exposure levels for airborne exposures based on gravimetric (i.e. mass/vol) dose-response relationships for large size particles may offer inadequate protection from nanoparticles. Animal bioassays suggest that inhaled nanoparticles may have the potential to induce pulmonary granulomas and fibrotic changes. Other research, both experimental and epidemiological, suggests that ultra-fine particulate, if not nanoparticulate, may be associated with an increased risk of cardiovascular morbidity and mortality. These health endpoints, if related to nanoparticulate exposure in the workplace, may be amenable to secondary prevention by medical surveillance. We will discuss methods of radiological imaging, pulmonary function testing, measurement of biochemical and immunochemical biomarkers of pulmonary and vascular inflammation, noninvasive assessment of cardiac function, and web-enabled methods of exposure and clinical data aggregation and analysis that might be candidate components of medical surveillance for these conditions. Prospective cohort studies on working populations with carefully defined exposures to nanomaterials will be needed to establish the sensitivity, specificity, and positive predictive value of these approaches. At this point in time, conduct of workplace medical surveillance for members of the nanotechnology workforce within the framework of voluntary clinical research is appropriate, ethical, and feasible.