Release of engineered nanomaterials from personal care products throughout their life cycle

The impetus for this study was to provide release estimates that can serve to improve predictions of engineered nanomaterial (ENM) exposure for risk assessment. We determined the likely release of ENMs from personal care products (PCPs) through a consumer survey on use and disposal habits, and research on the types and quantities of ENMs in PCPs. Our estimates show that in the US zinc oxide (ZnO), with 1,800–2,100 mt yr⁻¹, and titanium dioxide (TiO₂), with 870–1,000 mt yr⁻¹, represent 94 % of ENMs released into the environment or landfills from the use of PCPs. Around 36–43 % of ENMs from PCPs were estimated to end up in landfills, 24–36 % released to soils, 0.7–0.8 % to air, and 28–32 % to water bodies. ENMs in sunscreen represent around 81–82 % of total release, from ZnO and TiO₂ as UV blockers, followed by facial moisturizer (7.5 %), foundation (5.7 %), and hair coloring products (3.1 %). Daily care products such as body wash, shampoo, and conditioner had by far the highest per capita and total use, but contributed little to the ENM release estimates as these products generally contain little or no ENMs. However, if ENMs are incorporated into these daily care products, this may substantially increase ENM release.