Hormonal Waters

Oral contraceptives are not to blame for estrogen in the water supply

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) Addressing growing concern about the effects of birth control pills in the US supply of drinking water, scientists found that less than 1 percent of the estrogens that enter the water supply come from birth control pills.

The report, which suggests that most of the estrogens in our drinking water come from other sources, was conducted by University of California at San Francisco researchers Tracey Woodruff, Ph.D., MPH, Amber Wise, Ph.D., and Kacie O'Brien. Their findings are published in the journal Environmental Science & Technology.

Concern about estrogen in the drinking water stems from the sex hormone's role as an endocrine disruptor with possible adverse effects on people and wildlife, specifically fertility problems. Nearly 12 million women of reproductive age in the United States take the pill. Because those women's urine contains the hormone, some have hypothesized that the major source of estrogen contamination is oral contraceptives. However, Woodruff, Wise, and O'Brien point out that sewage treatment plants remove essentially all of the 17 alpha-ethinylestradiol (EE2), the main estrogen in oral contraceptives.

After analyzing multiple studies on the topic of estrogen contamination, the researchers found that EE2 has a lower predicted concentration in US drinking water than natural estrogens from soy products, dairy products, and untreated animal waste used as farm fertilizer. They also found that women taking the pill are not the only ones flushing down hormones. In fact, all humans, especially pregnant women, excrete hormones in their urine. According to some of the studies cited in the report, animal manure accounts for 90 percent of estrogens in the environment. Other studies suggest that if merely 1 percent of the estrogens in livestock waste reached waterways, it would account for 15 percent of the estrogens in the world's water supply.

Reviewed by: 
Review Date: 
December 8, 2010
Last Updated:
December 9, 2010