Excreted Drugs: Something Looks Fishy

Doctors recommend drinking plenty of water to replenish lost fluids and wash away wastes. Just where do the excreted wastes go? At least a few, including hormones and heart drugs, end up in streams—and eventually someone else’s drinking water, a new study finds.

Though the amounts detected in water from a Louisiana tap were small—just a few parts per trillion (ppt)—they can be biologically active, another study finds. At these concentrations, one of the hormones measured and another found in birth control pills alter the apparent gender of fish and, possibly, their fertility.

In a suite of yet more studies, collaborating state, federal, and university scientists report finding male carp and walleyes in Minnesota that were producing “sky-high” quantities of vitellogenin, an egg-yolk protein normally made only by females. Such feminization might explain the suspected inability of some adult male fish to make sperm. The researchers had caught the walleyes in the effluent of a sewage-treatment plant—a type of facility that others have shown can release estrogenic pollutants (SN: 3/21/98, p. 187: https://www.sciencenews.org/sn_arc98/3_21_98/bob1.htm).

Researchers reported all these findings last week in Minneapolis at a meeting sponsored by the National Ground Water Association.

Glen R. Boyd, a civil engineer at Tulane University in New Orleans, described a preliminary survey this spring of the anticholesterol drug clofibric acid, the pain reliever naproxen, and the hormone estrone in local waters. His team’s sampling turned up the drugs at three sites along the Mississippi River, at four sites around Lake Pontchartrain, and in Tulane’s tap water.

Though the drugs weren’t always detectable, assays revealed a minimum of 10 ppt of each at least once at every site. Estrone in tap water, for instance, averaged 35 ppt, with a high of 80 ppt.

Environment Canada detected similar pollutants in its 1998 nationwide survey of sewage-treatment effluent. At some sites, estrone reached 400 ppt and the hormone ethinylestradiol from birth control pills reached 14 ppt, notes Chris D. Metcalfe of Trent University in Peterborough, Ontario. He’s now exposed eggs of a laboratory fish, the Japanese medaka (Oryzias latipes), for 100 days to concentrations typical of the survey.

At exposures of 0.1 ppt ethinylestradiol or 10 ppt estrone, some males became intersex, exhibiting both male and female reproductive tissues. Exposures to 1,000 ppt of either of these estrogens transformed all males into females. The findings are slated to appear in Environmental Toxicology and Chemistry.

Though not a North American fish, the medaka models the reproductive responses of native fish well, Metcalfe says. In fact, his fieldwork around the Great Lakes has uncovered signs of intersex white perch. That’s worrisome, he observes, since intersex fish “usually aren’t interested in sex—in spawning.”

Moreover, in early March, Ira Adelman of the University of Minnesota in St. Paul caught male walleyes in local waters. He was able to extract sperm from all of them except those swimming in a channel that received effluent from a sewage-treatment plant.

The channel’s unusual warmth may have triggered these males to release their sperm early, he said. However, he noted, it’s also possible that those estrogenic pollutants that fostered males to produce egg-yolk protein also “arrested the fish in an early state of sexual development.” His team is now looking for testicular abnormalities in the fish.

Local carp, which normally spawn later, made sperm. But Adelman reported preliminary data indicating that sperm from males in the sewage-treatment-plant channel show somewhat slowed motility.

None of the new data are strong enough to indict pharmaceutical pollution for harming wildlife, much less people, notes Leroy C. Folmar of the Environmental Protection Agency in Gulf Breeze, Fla. However, he adds, the studies by Metcalfe and Adelman hint that estrogens in water may be capable of inducing “functional sterility” in exposed fish.

Christian G. Daughton of the EPA’s National Exposure Research Laboratory in Las Vegas says that Boyd’s tap water data will be “disturbing” if they’re confirmed. “If [drugs] are in drinking water now,” he warns, “you can be guaranteed they’ve been there as long as the drugs have been in use.”

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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