As information (and misinformation) proliferates in the media about endocrine-disrupting chemicals (EDCs), so do questions about where they are found and how we might be exposed to them through eating, drinking, breathing, or touching.
Answers to these questions are not always simple. There are nearly 85,000 man-made chemicals in the world, many of which people come into contact with every day. Only about one percent of them have been studied for safety; however, 1,000 or more of these chemicals may be EDCs based on their probable endocrine-interfering properties. Here are the most common EDC types and product categories.
Clothing, Furniture, and Electronics: Safety Comes with EDC Side Effects
Brominated flame retardants (BFRs) are used in electronics, clothing, and furniture such as sofas and mattresses to reduce flammability. Unfortunately, these chemicals also have been linked to abnormal hormone function in the thyroid, which plays a critical role in fetal and childhood development. Adding to the risk of exposure, BFRs often migrate out of their products over time where they may contaminate household dust and food.
Also, polychlorinated biphenyls (PCBs) were used in hundreds of industrial and commercial applications due to their non-flammability, as well as chemical stability and insulating properties. Although the EPA banned their manufacture in the United States in 1979, PCBs are still present in insulation, electrical equipment, caulking, oil-based paint, and more, and do not break down readily. In addition to being a long-acknowledged toxicant, PCBs are EDCs. As a class, they have the strongest and longest-known associations with neurological disorders.
Food Contact Materials: A Human Cost to Convenience and Protection
Phthalates interfere with the production of androgen (testosterone), a hormone critical in male development and relevant to females as well. Phthalates are used in hundreds of products, including many food and beverage containers and plastic wraps. People are exposed to these EDCs when they leach into foods or are released when containers are microwaved. Many companies have voluntarily removed phthalates from their products and advertise them as “phthalate-free”. Other plastic containers, which contain phthalates, have the number "3" and “V” or “PVC” in the recycling symbol.
Among the phenol class of compounds considered to be EDCs, bisphenol A (BPA) is one of the best known and most pervasive. In humans, it is linked to reduced egg quality and other aspects of egg viability in patients seeking fertility treatment.
Although BPA was banned in children’s products such as baby bottles, it’s still used in many water bottles and plastic containers and in the epoxy resins that protect canned foods from contamination. In these products, BPA leaching is enhanced by heating or reheating (such as in a microwave), or exposure to sunlight or acidic foods (such as tomatoes).
Children’s Products: Despite Regulations, Risks Still Abound
EDCs are gradually being regulated and banned in children’s toys, games, and accessories such as baby bottles. However, products that are older, manufactured outside of the United States and European Union, or battery-operated may be of particular concern.
Phthalates, which add fragrance to products and make them more pliable, interfere with hormone production, as mentioned above. The European Union has restricted some members of this EDC class since 1999, and the United States has similarly restricture their use since 2008. Phthalates are usually identified on product labels by the specific compound: The eight most common are BBP, DBP, DEHP, DEP, DiDP, DiNP, DnHP, and DnOP.
Lead – long acknowledged as a neurological toxicant – has also been linked with adverse female reproductive functions in animal, in-vitro, and human epidemiological studies. While lead has been banned in house paints, dishes, and cookware in the United States since 1978, this EDC may still be found in a product’s paint – especially in products manufactured in countries which still allow lead-based paint – and in plastics where lead is still allowed for softening and stabilizing against heat.
Studies by the International Persistent Organic Pollutants Elimination Network (IPEN), a non-governmental organization working for safe chemical policies in the developing world, reported lead in 18 percent of children’s products in Russia and surrounding nations, 15 percent in the Philippines, and 10 percent in five cities in China.
Cadmium is a natural element used in batteries, pigments, plastic stabilizers, alloys, and coatings. It has in recent years fallen under increased regulation as a carcinogen and pollutant. Cadmium may also be an EDC; research suggests a link to a wide range of detrimental effects on the reproductive system.
Pesticides and Herbicides: Dangerous to Humans as Well
Many pesticides are designed to be toxic to pests’ nervous or reproductive systems and may act by disrupting endocrine systems. Such chemicals are also EDCs because of the similarities between insect and animal endocrine systems.
Chlorpyrifos, an insecticide used in commercial agriculture, is a potent neurotoxicant that causes developmental delays, attention problems, and ADHD in children. It accumulates in soil, water, food, and air, as well as in buildings. That’s why the United States banned its residential uses in 2000, and the effect was immediate: children’s blood levels of chlorpyrifos in New York declined significantly in one year and were reduced to less than half in two years.
DDT, one of the best-known pesticide EDCs, was used extensively worldwide until it was banned in the 1970s by several countries, including the United States and European Union nations. It remains in use in regions such as India and Africa to fight insect-borne disease. Emerging evidence suggests that exposure to this neurotoxin might be associated with breast cancer, preterm birth, early pregnancy loss, reduced semen quality, disrupted menstruation, and problems with lactation.
EDCs can also be found in herbicdes that control plant life. Atrazine, a widely-used herbicide, has been shown to affect the hypothalamus and pituitary glands. Some studies have also proposed causal relationships between glyphosate, used to kill weeds on lawns and farms, and obesity, behavioral, and cognitive disorders.