A weight-of-evidence approach to identify nanomaterials in consumer products: a case study of nanoparticles in commercial sunscreens

Nanoscale ingredients in commercial products represent a point of emerging environmental concern due to recent findings that correlate toxicity with small particle size. a weight-of-evidence (woe) approach based upon multiple lines of evidence (loe) is developed here to assess nanomaterials as they exist in consumer product formulations, providing a qualitative assessment regarding the presence of nanomaterials, along with a baseline estimate of nanoparticle concentration if nanomaterials do exist. electron microscopy, analytical separations, and x-ray detection methods were used to identify and characterize nanomaterials in sunscreen formulations. the woe/loe approach as applied to four commercial sunscreen products indicated that all four contained at least 10% dispersed primary particles having at least one dimension <100 nm in size. analytical analyses confirmed that these constituents were comprised of zinc oxide (zno) or titanium dioxide (tio2). the screening approaches developed herein offer a streamlined, facile means to identify potentially hazardous nanomaterial constituents with minimal abrasive processing of the raw material.