Phthalates, ethinylestradiol, bisphenol, atrazine. The names may sound exotic, but they are the stuff of modern life...found in shampoo, birth control pills, suntan lotion, food containers, product fragrances, children’s clothing and more. Every day, we are showered with hundreds of thousands of chemicals. Additionally, more than 1,000 new compounds are introduced annually. 

The Center for Disease Control (2005) states that humans are, at minimum, exposed to hundreds of environmental chemicals, many of which are EDCs. A commonly held theory in toxicology is “the dose makes the poison.” That is, a high dose will be more harmful than a low dose. The high dose then, is at the heart of many regulatory efforts to gauge a “safe” level. However, two qualities mark EDCs as a long-term environmental health problem: additivity and persistence.

Additivity. Experiments with phthalates—common plasticizers/thickeners used in personal care products and household items—showed a marked interruption in male development. Evidently these different chemicals target similar pathways, resulting in an additive effect (e.g., no effect with one compound, but a significant rate for a birth defect when the subject is exposed to more than one compound, even at low levels). Additionally, research has shown that chemical present at “no observed effect concentrations” may contribute to cumulative effects of a mixture. The additive impacts of EDC mixtures may help explain the historical increase in incidence of many developmental disorders.

Persistence. Another characteristic of EDCs is persistence or lifespan; that is, how long the compound remains unchanged in an environment. The longer the chemical persists in water, air, or soil, the higher chance that humans will interact with it. Additionally, persistence of a chemical can lead to the build-up—or bioaccumulation—of that compound in an animal. When bioaccumulation occurs in a lower organism on the food chain, such as DDT or PCBs in the fat tissue of fish, higher organisms such as humans or birds of prey consume greatly magnified concentrations of these chemicals. In this way, humans can consume dangerous levels of a compound despite the compound existing within legal limits in water or other environmental sources