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More of the Estrogen Pollution Found in Waterways Comes from Factory Farms Than from Oral Contraceptives

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Oral contraceptives often take the blame for estrogen pollution in rivers, lakes, and reservoirs, but a new meta-study from researchers at the University of California, San Francisco, reports that oral contraceptives are not the source of most of the estrogens found in waterways Environ. (Sci. Technol., DOI: 10.1021/es1014482).

Estrogen in water has raised concerns because, in laboratory and field tests, the synthetic estrogen found in birth control pills disrupts reproduction in several fish species, such as the South European roach (Rutilus rutilus). The hormone can trigger male fish to develop female reproductive organs and to produce eggs. And researchers have connected estrogens in drinking water to human fertility problems and cancers.

Nearly 11 million American women use oral contraceptives, according to the Guttmacher Institute, a nonprofit organization that researches sexual and reproductive issues. Most contraceptives contain a mixture of synthetic estrogen and progestin. These chemicals flow into wastewater treatment systems via urine and feces.

But estrogen-like chemicals also enter waterways from other sources, such as large-scale animal farms, landfills, and non-birth-control pharmaceuticals. Also, people of both sexes and all ages excrete natural estrogens.

To better understand the sources of estrogens in drinking water, UC San Francisco postdoctoral fellow Amber Wise and her colleagues reviewed 82 studies. Using the data they gathered, the researchers estimated that ethinylestradiol, the most commonly used synthetic estrogen in the birth control pill, likely accounts for less than 1% of the total estrogens excreted by Americans. In addition, the researchers found evidence for other estrogen sources that could play an important role in contaminating surface waters.