Environmental Studies

Story posted December 02, 2010

Event date(s): December 03, 2010 — December 03, 2010

The environmental impacts of sunblock products: Environmental photochemistry of ultraviolet filter chemicals
Laura MacManus-Spencer, Assistant Professor of Chemistry, Union College
Friday, Dec. 3 3-4 pm
Druckenmiller Hall, Room  20

In order to make decisions about the regulation and environmental remediation of pharmaceuticals and personal care products (PPCPs) it is important to understand their fate in the environment. One class of PPCPs of current environmental concern comprises ultraviolet (UV) filter chemicals, which are used in sunblock, lip balm, and other personal care products to protect the skin from harmful UV radiation. These chemicals enter the environment via direct (e.g., swimming) and indirect (e.g., showering and washing clothes) routes. In this study, we have investigated the environmental photochemistry of four UV filter chemicals, benzophenone-3 (oxybenzone), octyl methoxycinnamate (octinoxate), octyl dimethyl para-aminobenzoic acid (padimate-O), and homomenthyl salicylate (homosalate). Experiments were conducted under natural and simulated sunlight to determine quantum yields, environmental half-lives, and the relative importance of direct (degradation as a result of absorption of light) and indirect (degradation mediated by photo-generated excited species) photolysis for each chemical. Photolysis products have been identified where possible. Oxybenzone does not degrade by direct or indirect photolysis. Homosalate does not undergo direct photolysis but is susceptible to indirect photolysis. Octinoxate and padimate-O degrade readily by direct photolysis, and several degradation products have been identified for each chemical.