Endocrine-Disrupting Chemicals By Angela S. Hoover Endocrine-disrupting chemicals (EDCs) are substances in the environment – the air, soil and water, food sources and manufactured products – that interfere with the normal functioning of the body’s endocrine system, which produces and releases hormones. When the endocrine system functions properly, it works with other body systems to help maintain and control metabolism (how the body converts food to fuel), reproduction, growth and development, and the way the body handles stress and responds to the environment.

Most EDCs are synthetic chemicals designed for use in numerous industries. Classes of these chemicals include:

• Industrial solvents or lubricants and their byproducts: polychlorinated biphenyls (PCBs) and dioxins

• Plastics, plasticizers: bisphenol A (BPA), phthalates

• Pesticides: methoxychlor, chlorpyrifos, DDT

• Fungicides: vinclozolin

• Herbicides: atrazine

• Antibacterials: triclosan

These chemicals are found in consumer products like plastics, household cleaners, health and beauty products (toiletries including soaps, shampoos, shaving creams, lotions and cosmetics) and fabrics treated with flame retardants. They are also found in the food chain due to soil leaching and water pollution. EDCs are particularly concentrated in fish and other aquatic animals, and male species lacking male reproductive organs, due to high exposure to estrogen-mimicking EDCs, has been occurring for quite some time. People who work with pesticides, herbicides, fungicides and industrial chemicals have an even higher exposure than the typical consumer. Infants can additionally be exposed through breastfeeding, soy-based formula feeding, and through plastic bottles. Some medications can also disturb endocrine function.

Some EDCs occur naturally in food, such as phytoestrogrens. Phytoestrogens are plant substances that produce effects similar to those of the female sex hormone estrogen. Soy beans and flax seeds are high in phytoestrogen content. However, a person would need to consume substantial amounts of phytoestrogen-rich foods in order to have an adverse effect on the endocrine system.

Some EDCs, such as DDT, BPA, phthalates and PCBs, can mimic or block the effects of female and male sex hormones. The impact of early exposure to these EDCs can be seen throughout life. Before birth, exposure can interfere with fetal growth and development. During puberty, sexual development may be effected, and decreased fertility or diseases of the reproductive systems in both males and females can develop. Later in life, after long term, low grade exposure to these and other EDCs, various conditions like allergies and a wide array of syndromes can occur. Other EDCs can affect other endocrine systems like the thyroid and neuroendocrine systems. Studies have shown that many industrial chemicals can interfere with thyroid function, which is vital for normal brain development, control of the metabolism and other aspects of normal bodily function.

High levels of certain EDCs are known to cause endocrine, reproductive or neurological problems in humans. High level exposure comes from toxic spills and long-term environmental contamination. An industrial accident in Seveso, Italy in 1976 exposed the local population to high levels of dioxins. Studies have shown that dioxin exposure increases the risk of diabetes and certain types of cancer, in addition to other health problems. Low levels of EDCs are not as well-known as high level exposures. However, studies in animals with low dose exposure show definite harm to health and scientists suspect similar effects in humans.

Presently, one of the greatest obstacles to concrete cause-and-effect evidence is because environmental contamination and overall human exposure to EDCs is rarely due to a single chemical or compound. This makes understanding the effects of individual EDCs all the more complicated and nearly impossible to discern. Also, identifying an EDC or EDCs to health problems is difficult since people are exposed to so many complex mixtures of chemicals every day. Scientists are working to better understand EDCs and human health, despite these complications. In the meantime, be wary of the chemicals in the products you use and try to replace these products with ones that do not include these chemicals.

For more information, check out these web sites:

www.niehs.nih.gov - National Institute of Environmental Health Sciences

www.psr.org/resources/pediatric-toolkit.html - Pediatric Environmental Health Toolkit 

www.dhs.ca.gov/ohb/HESIS/hesispubs.htm - Hazard Evaluation System and Information Service

www.ewg.org - Environmental Working Group