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Chemicals that Disrupt our Hormone Systems

Down the Drain: Chemicals that Disrupt our Hormone Systems

July 12, 2007

From the moment of conception, human growth and development is regulated by tiny amounts of biochemicals called hormones. Our bodies manufacture trace quantities of these chemical messengers, which enter our bloodstream and travel throughout our systems, managing our metabolism and controlling the function of our organs. Hormones are able to produce an array of sophisticated regulatory signals crucial to human health at part per billion or part per trillion levels in the blood. Disruption of the human hormone (or endocrine) system can cause a broad range of illnesses, including reproductive and metabolic disorders and cancer.

Many man-made chemicals widely used today may be capable of causing hormone-disrupting effects in people, fish, and wildlife. 3 hormone-disrupting chemicals were the focus of this study: phthalates, a class of chemicals used in products ranging from cosmetics to plastics; bisphenol A, a chemical used to make a type of hard plastic (polycarbonate), and to make an epoxy resin that lines food cans; and triclosan, an antibacterial ingredient found in numerous consumer products, including liquid hand soap, toothpaste, plastic cutting boards, and shoe insoles.

These chemicals have been detected in streams and rivers as a result of exposure to wastewater from our communities (Kolpin 2002). Wastewater treatment is extremely effective at removing biodegradable pollutants such as human and food waste, but it cannot remove all of the unregulated tide of persistent chemicals washed down the drain.

Phthalates, bisphenol A, and triclosan have also been detected in people (Calafat 2005; CDC 2005; Wolff 2007). Laboratory studies have revealed evidence that these chemicals can disrupt animal hormone systems at levels comparable to those found in ordinary Americans (e.g. Nagel 1997; Mylchreest 2000; Veldhoen 2006). Research on people has also linked specific adverse health effects to exposures to some of these chemicals (Hanaoka 2002; Duty 2003, 2004, 2005; Sugiura-Ogasawara 2005; Swan 2005; Main 2006; Takeuchi 2006; Hauser 2007; Meeker 2007; Stahlhut 2007).

A critical insight of recent research is that chemicals that interfere with the hormone system can alter biological systems even when present at extremely low levels, as low as 1 part in 1 trillion (Wozniak 2005). While it may seem surprising that such small amounts of a chemical could affect health, only small amounts of hormones are necessary to regulate our metabolism naturally. A man-made chemical that, for example, is similar in shape to a hormone, and can mimic that hormone when it is present in the body, might disturb the hormone system even when present at a low concentration.

Current chemical regulations in the United States do not require that new or existing chemicals be tested for their ability to disrupt the hormone system. As a result, numerous consumer products are made using chemicals suspected of causing hormone disruption, including phthalates, bisphenol A, and triclosan. We may be exposed to these chemicals every time we use these products, and through our use of them, release them into the environment where they may impact fish and wildlife.

As a result, use of hormone disrupting chemicals creates a burden not only for our bodies, but also for surrounding fish and wildlife. Our analyses suggest that wastewater from a typical urban area may contain phthalates, bisphenol A, and triclosan. Though this wastewater is treated before it is released into the environment, typical wastewater (sewage) treatment methods were not designed to degrade the thousands of synthetic chemicals now present in the waste stream. While some chemicals are removed by treatment to some extent, others persist and may contaminate surrounding streams and oceans (e.g. Kolpin 2002; Oros 2002). Fish living in contaminated waters may develop a variety of reproductive problems due to this assault on their hormone systems. For example, male fish, exposed to treated wastewater, that produce immature eggs in their testes have been discovered in many parts of the United States (Pait 2002; Goodbred 2007).

The best way to reduce exposures to hormone disrupting chemicals is to avoid using them in the first place. By eliminating these chemicals at the source, we prevent human exposures from consumer products, and we prevent fish and wildlife exposures from our wastewater. By choosing products that do not contain hormone-disrupting chemicals, you protect your own health and the health of your family, and you reduce the amount of pollution entering the environment.

For truly broad change, however, we need to update chemical regulations at the federal level. Our government must acknowledge the new science that clearly shows that some chemicals that act on the hormone system can produce health effects at very low levels, and should not be used in consumer products. Updated chemical regulations should ensure that chemicals used in the United States be safe for people and for the environment.