How Endocrine Disrupting Chemicals Harm
Endocrine Disrupting Chemicals (EDCs) are synthetic compounds that alter hormone systems and can cause adverse health effects. EDCs are the same shape as hormones, so rather than poisoning the body, they are recognized by receptors in the body. Hormones are responsible for coordinating genetic activity, protein production, cellular metabolism and tissue development. Hormones guide the chemical processes that activate and repress gene expression, thereby shaping the production of proteins, cellular metabolism, and tissue development. EDCs can have subtle but long-lasting effects on individuals, their descendants, or on populations; because of how gene expression works a mother’s exposure to EDCs could affect her unborn daughter’s children. Sensitivity to EDCs is greatest when the hormone system is working at its height, which includes fetal development, infancy and childhood, puberty, and during breastfeeding.
Low Doses: hormone systems have receptors and feedback loops that respond differently depending on the dose of exposure to hormones—or their mimics, which include synthetic EDCs. Even low doses of an EDC can participate in metabolic and gene expression processes that are sensitive to low levels of hormones. These low dose responses cannot be extrapolated from tests that examine the impact of higher dose exposures to EDCs. EDCs may in fact have the greatest effect at low doses (called a non-monotonic dose-response curve), especially when the exposures are chronic. Low doses can have profound effects at particular pivotal windows of bodily development, such as prenatal development or in infancy.
Pivotal Windows of Development: Sensitivity to EDCs is greatest when the hormone system is working at its height, which includes pivotal windows of bodily development such as fetal development, infancy and childhood, puberty, and during breastfeeding. They also affect women more than men. When chemicals with hormone mimicking or disrupting activity are present even at low doses during these developmental windows, they affect gene expression, which in turn affects the unfolding development of the many millions of specialized cells that make up the blood, bones, brain, and other tissues. In these pivotal periods, EDCs can interfere with the activities of hormones involved in development, and thus may result in significant and irreversible changes to the structure or function of a physiological system. Because of the uneven harm to infants, children, and women, exposure to EDCs are an environmental justice issue.
Harms: Health effects from EDCs include, but are not limited to, lowered fertility in males, reproductive health problems in females, thyroid disorders, brain development disorders and learning debilities in children, obesity, early onset puberty and senility, some forms of cancer, skewed sex ratios in populations, diabetes and other metabolic disorders, and population declines in wildlife.
Ubiquity: Human exposure to EDCs occurs through ingestion of food, dust, and water, through inhalation of gases and particles in the air, and through the skin. Some known EDCs are built into the products and materials of our everyday environment. We call these Built-In Exposures. Thus, the health impacts of EDCS do not depend on high doses; low dose and chronic exposures to EDCS, which are found ubiquitously in our environments, can produce significant and lasting harm. Consumer choice cannot protect us from EDCs because of their ubiquity. EDCs can be transferred from a mother to a fetus, and through breastmilk. To date, every person tested in every country, including fetuses, have had EDCs in their bodies. The World Health Organization (WHO) estimates that there are over 800 EDCs or suspected EDCs in production today, but only a fraction have been investigated for toxicity. A few known EDCs include: DDT, a pesticide; bisphenol A (BPA), a chemical used in hard, polycarbonate plastics and cash register receipts; flame retardants like PBDEs and FireMaster 550; and phthalates commonly found in soft toys, flooring, medical equipment, cosmetics and air fresheners. Only a few of these compounds have been banned. Most others are still found in common everyday products.
Reproductive and Environmental Justice values must guide a renewed effort to regulate EDCs retardant chemicals. Meaningful implementation of the precautionary principle, responsive to scientific research on EDCs and the low-dose effects of chemicals at pivotal windows of development, demands decisive regulatory action to address the problem of ubiquitous Built-In exposures to EDCs.
Short Summary for Decision Makers
Publications for Action
- State of the Science of Endocrine Disrupting Chemicals 2012 (WHO, 2013)
- Endocrine Disrupters and Child Health (WHO, 2012)
- EDC-2: The Endocrine Society’s Second Scientific Statement on Endocrine-Disrupting Chemicals (2015)