Many aquatic and amphibian species are being exposed to traces of drugs, ranging from Prozac to birth control pills, that end up in U.S. waterways in ever-increasing amounts.
According to a CNN report filed today by Marsha Walton, scientists have confirmed that this mix of pharmaceuticals may lead to problems serious enough to prevent wildlife reproduction.
In 2002, the U.S. Geological Survey tested 139 rivers in 30 states. Eighty percent of those streams showed evidence of drugs, hormones, steroids, and personal hygiene products such as soaps and perfumes.
Researchers are working on several fronts to learn the extent of the problem, as well as the potential short- and long-term ecological effects on wildlife.
Marsha Black, an aquatic toxicologist at the University of Georgia in Athens, found that low levels of common anti-depressants including Prozac, Zoloft, Paxil and Celexa cause development problems in fish, and metamorphosis delays in frogs.
"In mosquitofish, markers of sexual maturity were delayed in both males and females," Black told Walton in her report.
And in a test of two tadpoles, after 57 days of development in the lab the one exposed to fluoxetine (Prozac) had yet to sprout limbs, while the other experienced normal growth.
Black explained that time is of the essence to the survival of many water creatures during their life cycles. For example, frog eggs are often laid in temporary ponds and wetlands. If tadpoles have not completed metamorphosis by the time the water dries up, they will die without reaching adulthood.
In the next phase of her study, funded by the Environmental Protection Agency, Black plans to examine the reproductive tissue of fish affected by the anti-depressants.
Sewage treatment plants currently are not equipped to filter out any of the myriad prescription drugs present in wastewater. Experts agree it would require a large financial investment in plants nationwide to install equipment designed to remove the pharmaceuticals.