The Cloudy side of sunscreens

In a study published in this issue of ES&T (pp 1427–1431), a team of scientists report high concentrations of two sunscreen ingredients in fish tissue samples taken from rivers in northern Switzerland. The findings imply that on a hot summer day, chances are that if people are wearing sunscreen, it’s also likely to be in their drinking water or fish dinner.

Both Europe and the U.S. have consumer-protection guidelines for many UV-inhibitor products, such as sunscreen lotions, lip balms, and cosmetics. However, regulatory agencies are well behind the curve on the environmental risks they pose.

Many of the lotions, lip balms, and other cosmetics that we slather on to protect us from the deleterious effects of too much sun exposure contain chemical compounds that absorb ultraviolet (UV) radiation. When people swim, the UV filters in these products can be transferred from their skin into lakes and streams. The chemicals also wash off in the shower and are funneled to wastewater treatment plants, where traces can escape via treated effluent into the environment. However, although consumer-protection guidelines are in place for many of these UV-inhibitor products in both Europe and the U.S., regulatory agencies have placed less emphasis on the environmental risks that they pose.

Annual production figures for UV filters are estimated in the hundreds of metric tons, according to a previous study on the chemical contents of wastewater by the new study’s corresponding author Marianne Balmer. She conducted this latest study with a team of chemists at the Swiss agriculture department’s federal research station (Agroscope FAW) in Wädenswil and the Swiss Federal Laboratories for Materials Testing and Research’s Laboratory of Organic Chemistry in Dübendorf.

All of the 19 fish tested in the recent study had traces of 2 of the most commonly used UV filters in Europe—4-MBC (4-methylbenzylidene camphor) and OC (octocrylene). Both chemicals biodegrade slowly and can bioaccumulate, according to the researchers.

Compared with another FAW study that analyzed fish from remote Swiss mountain lakes, the river fish accumulated much higher concentrations of both chemicals. Lipid-weight-based concentrations of 4-MBC in the lake species—whitefish (Coregonus) and roach (Rutilus rutilus)—ranged from 20 to 170 ppb. The brown trout (Salmo trutta fario) from the rivers tested in the current study had concentrations ranging from 50 to 1800 ppb. OC was mostly absent in the lake fish but was found in the river fish at concentrations from 40 to 2400 ppb.

The nearly 10-fold difference in concentrations among lake and river fish sheds light on the environmental transport and fate of these chemicals. “The study shows that UV filters were present in fish from rivers that receive inputs of wastewater,” says Hans-Rudolf Buser, one of the report’s coauthors. “One might argue, therefore, that aerial transport is not a major pathway for the presence, or the distribution, of UV filters in the environment and fish.”

The Swiss government’s work takes research on pharmaceuticals and personal care products (PPCPs) in the environment to the next level in the U.S., says Dana Kolpin, a hydrologist with the U.S. Geological Survey (USGS). Although the U.S. EPA does not regulate any personal care products and 4-MBC and OC are not currently on USGS’s monitoring list, Kolpin says that Balmer’s work will help USGS decide how to prioritize further study on specific PPCPs. USGS is modifying its sediment analysis method to include some UV inhibitors and will soon establish a new monitoring protocol for these substances in water, he adds.

4-MBC is a known endocrine disrupter and was detected in human milk in a 1997 study in Germany, according to Margret Schlumpf, a toxicologist at the University of Zurich’s Group for Reproductive, Endocrine, and Environmental Toxicology, which researches the health effects of UV filters. In studies with rats, Schlumpf has shown that some UV filters, including 4-MBC at levels as low as 7 mg per kg of body weight each day, can alter reproductive function and affect birth weight and postnatal survival rates. The significantly higher concentrations in river fish reported in the new study are shocking, she says, and will help further her research.

But industry sources maintain that UV filters do not produce harmful endocrine-disruption effects. Industry studies on the health impacts and environmental fate of both 4-MBC and OC, which are currently under review by EU officials, have shown that there is no risk of these chemicals contaminating the food chain at harmful levels, according to Gerald Renner, director of science and research at the European Cosmetic Toiletry and Perfumery Association. —TASHA EICHENSEHER