National scale down-the-drain environmental risk assessment of oxybenzone in the United States

Organic ultraviolet (UV) filters are used in cosmetic and personal care products (CPCPs) and over-the-counter (OTC) sunscreens, due to their ability to absorb solar radiation. When OTC and CPCP ingredients are washed down the drain, they can then enter freshwaters that receive wastewater treatment plant effluents. This paper presents a freshwater environmental safety assessment of a key UV filter, oxybenzone, used in OTC sunscreens and CPCPs in the United States. Exposure was characterized using iSTREEM®, a spatially resolved aquatic exposure model developed for chemicals disposed of down the drain. iSTREEM® provides a comprehensive exposure assessment of oxybenzone concentrations in United States receiving waters through predicted environmental concentration (PEC) distributions representative of conditions across the region. A review of available hazard data was used to derive a predicted no-effect concentration (PNEC) using aquatic toxicity data and assessment factors. A safety assessment was conducted by comparing the PEC distribution with the PNEC. The results indicate that oxybenzone is of low concern and there is a significant margin of safety as the 90th percentile PEC is two orders of magnitude below the PNEC. These results are instrumental in demonstrating the environmental safety of key organic UV filters in the U.S. freshwater environment and will help prioritize future work. Integr Environ Assess Manag 2021;17:951–960. © 2021 Personal Care Products Council. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC) KEY POINTS A freshwater environmental risk assessment for oxybenzone was conducted that considered available aquatic toxicity data and down-the-drain emissions of sunscreen, cosmetic, and personal care products. A nationwide distribution of predicted environmental concentrations was modeled, using the spatially explicit iSTREEM® exposure model, and the median and 90th percentile oxybenzone concentrations were predicted to be 0.01 and 0.15 µg/L, respectively. The 90th percentile exposure prediction (reasonable worst case) is two orders of magnitude below the predicted no-effect concentration value of 18 µg/L, indicating that risk is negligible. This paper provides a down-the-drain freshwater environmental risk assessment framework suitable for over-the-counter drugs, cosmetic, and personal care ingredients.