Troubled waters

KA Kidd et al., “Collapse of a fish population after exposure to a synthetic estrogen,” Proc Natl Acad Sci, 104(21):8897–901, 2007. (Cited in 86 papers)

Researchers have linked feminized male fish downstream of municipal wastewater outlets with elevated levels of estrogen and other chemicals, but knew little about the impact on fish population sustainability. During a 7-year, whole-lake experiment, the researchers, led by Karen Kidd at the University of New Brunswick, demonstrated that populations of fathead minnows collapsed to the brink of extinction after being exposed to low concentrations of 17 alpha-ethynylestradiol (synthetic estrogen used in birth-control pills).

Many chemicals are regulated by the United States, but pharmaceuticals are still not included on the list. In recent years, however, research (particularly Kidd’s) that has found these drugs alter endocrine systems in wildlife has fueled the policy debate over whether to regulate pharmaceuticals in waterways.

Happily, the study substantiated population modeling based on lab data. “When Kidd’s results matched what had been modeled, it was proof that the system of modeling for endocrine disruptors was accurate,” says Gerald Akley, a toxicologist for the US Environmental Protection Agency.

Kidd and her colleagues stopped adding estrogen to the lake, located at the Experimental Lakes Area in northern Ontario, in 2003 and “the fish are recovering slowly but surely,” says Kidd. “It is refreshing to see that even after such a dramatic decline, it is possible for impacted populations to bounce back.”