Classic Toxicology vs. New Science

Endocrine-disrupting chemicals (EDCs) are compounds that interfere with hormone action. Many EDCs are agonists or antagonists of estrogen, androgen, or thyroid hormone receptors. EDCs are found in many consumer products and are detected at low doses in humans. Using traditional methods from toxicology and risk assessment, these compounds have often been considered benign based on the low exposure levels and few overt signs of toxicity. However, thousands of epidemiology studies have found associations between EDC exposures and disease outcomes, suggesting that the methods used to prioritize chemicals and identify safe levels of exposure have failed. This chapter discusses the unique properties of EDCs that defy traditional chemical safety expectations. The presumption that chemicals are safe until proved harmful has allowed humans to be exposed to hundreds of chemicals that may be unsafe, at least during sensitive periods of development. Recommendations are offered for revising toxicologic evaluations to protect public health.