Sunscreen residue washed off in showers and sinks is reportedly sexually altering some male fish off the Southern California coast.

A University of California-Riverside scientist told the Riverside Press-Enterprise a chemical used in sunscreen products is causing some male fish to develop ovary tissue and female egg proteins.

Dan Schlenk said oxybenzone -- which protects skin from ultraviolet light and mimics the chemical properties of estrogen -- survives the sewage-treatment process and settles on the ocean floor. It then is consumed by bottom-dwelling fish, such as sole and turbot.

Schlenk told the Press-Enterprise although the chemical is similar in structure to estrogen, the female sex hormone, for some undetermined reason natural estrogen apparently doesn't feminize male fish.

A professor of aquatic eco-toxicology, Schlenk presented his study during this week's 26th annual meeting of the Society of Environmental Toxicology and Chemistry, in Baltimore.

Copyright 2005 by United Press International