Contrary to popular belief, birth control pills account for less than 1% of the oestrogens found in the nation's drinking water supplies. This was the conclusion of research scientists after conducting a study on the topic, the results of which appear in the American Chemical Society's bi-weekly journal Environmental Science & Technology.
The hormone oestrogen is a source of concern as an endocrine disrupter with possible adverse effects on people and wildlife. However, the published report (Are Oral Contraceptives a Significant Contributor to the Estrogenicity of Drinking Water?) suggests that most of the sex hormone enters drinking water supplies from other sources.
Authors Wise et al. note ongoing concern about possible links between chronic exposure to oestrogens in the water supply and fertility problems and other adverse human health effects. Almost 12 million women of reproductive age in the United States take the pill, and their urine contains the hormone. These statistics have led to the common belief that oral contraceptives are the major source of oestrogen in lakes, rivers and streams.
However, with knowledge that sewage treatment plants remove virtually all of the main oestrogen (17 alpha-ethinylestradiol or EE2) in oral contraceptives, the scientists decided to pin down the main sources of oestrogens in water supplies.
Their analysis found that EE2 has a lower predicted concentration in US drinking water than natural oestrogens from soy and dairy products and animal waste used untreated as a farm fertilizer. They also discovered that all humans (men, women and children and especially pregnant women) excrete hormones in their urine, not just women taking the pill. Some research cited in the report suggests that animal manure accounts for 90% of oestrogens in the environment. Other research estimates that if just 1% of the oestrogens in livestock waste reached waterways, it would comprise 15% of the oestrogens in the world's water supply.