Introduction
Endocrine disrupting chemicals (EDCs) are natural or man-made chemicals that can mimic, block, or interfere with the body’s hormones, which are part of the endocrine system. These chemicals are associated with a wide range of health problems.
The endocrine system
Endocrine glands, located throughout the body, produce hormones that act as signaling molecules after their release into the circulatory system. The human body depends on hormones for a healthy endocrine system, which controls many biological processes such as normal growth, fertility and reproduction. Hormones act in extremely small amounts, and minor disruptions in these levels can result in significant biological and developmental effects.
How do we encounter these chemicals?
Endocrine disruptors are present in many everyday products, including certain cosmetics, food and drink packaging, toys, carpets and pesticides. Some chemicals that act as flame retardants may also be endocrine disruptors. Contact with these chemicals can occur through air, food, skin and water. Endocrine disruptors cannot be completely avoided or removed; however, you can make informed choices to reduce exposure and the risk of potential health effects.
Chemicals that can disrupt your endocrine system
According to the Endocrine Society, there are nearly 85,000 man-made chemicals in the world, and 1,000 or more of them could be endocrine disruptors, due to their unique properties. The following are some of the most common and well-studied.
- Atrazine is one of the most commonly applied herbicides in the world, often used to control weeds in corn, sorghum and sugarcane crops.
- Bisphenol A (BPA) is used to make polycarbonate plastics and epoxy resins. It is used in manufacturing, food packaging, toys and other applications. BPA resins can be found in the interior coating of some canned foods and beverages.
- Dioxins are a byproduct of certain manufacturing processes, such as herbicide production and paper bleaching. They can be released into the air during waste burning and forest fires.
- Perchlorate is a colorless salt manufactured and used as an industrial chemical to make rockets, explosives, and fireworks, which can be found in some groundwater.
- Per- and polyfluoroalkyl substances (PFAS) are a large group of chemicals widely used in industrial applications, such as firefighting foam, nonstick pans, paper, and textile coatings.
- Phthalates constitute a large group of compounds used as liquid plasticizers. They are found in hundreds of products, including certain food packaging, cosmetics, perfumes, children’s toys and medical device tubes. Cosmetics that may contain phthalates include nail polish, hairspray, aftershave lotion, cleanser and shampoo.
- Phytoestrogens are natural substances with hormone-like activity found in certain plants; they may have an effect similar to that of estrogen produced by the body. Soy foods, for example, contain phytoestrogens.
- Polybrominated diphenyl ethers (PBDE) are used to make flame retardants for products such as furniture foam and carpets.
- Polychlorinated biphenyls (PCBs) have been used to manufacture electrical equipment, such as transformers, and are used in the composition of hydraulic fluids, heat transfer fluids, lubricants and plasticizers. PCBs were mass produced around the world until they were banned in 1979.
- Triclosan is an ingredient that was previously added to some antimicrobial and personal care products, such as liquid body washes and soaps.
How do people encounter endocrine disrupting chemicals?
People can be exposed to endocrine disruptors through foods and beverages consumed, pesticides applied, and cosmetic products used. Essentially, your contact with these chemicals can occur through food, air, skin and water.
Even low doses of endocrine-disrupting chemicals can be dangerous. Normal endocrine function in the body involves very small changes in hormone levels, but we know that even these small changes can have significant biological and developmental effects. This observation leads scientists to believe that exposure to endocrine disruptors, even at low doses, can alter the body’s sensitive systems and lead to health problems.
When absorbed into the body, an endocrine disruptor can decrease or increase normal hormone levels (left), mimic the body’s natural hormones (middle), or alter natural hormone production (right) .
What does the NIEHS do?
For more than three decades, NIEHS has been a pioneer in conducting research on the health effects of endocrine disruptors. NIEHS-funded research provides a better understanding of how endocrine disruptors can harm our health and cause disease.
This work began with studies of the endocrine disrupting effects of the drug diethylstilbestrol (DES). From the 1940s to the 1970s, DES was used to treat women with high-risk pregnancies, with the mistaken belief that it prevented miscarriages. In 1972, prenatal exposure to DES was linked to the development of a rare form of vaginal cancer in girls whose mothers took DES, as well as many noncancerous changes in sons and daughters. NIEHS experiments with DES successfully replicated and predicted health problems, which was helpful in uncovering how DES can harm well-being.
NIEHS participated in the development of a consensus statement in 2019 on the main characteristics of endocrine disrupting chemicalswhich provides a framework to help scientists evaluate potential endocrine disruptors.
NIEHS conducts cutting-edge research on endocrine disruptors to understand how they work and define their role in health and disease. Current areas of research include:
- Develop new models and tools to better understand the functioning of endocrine disruptors
- Develop and apply elevated tests to identify substances with endocrine disrupting activity
- Conduct research on animal and human health to define the links between exposure to endocrine disruptors and health effects
- Develop new assessments and biomarkers of exposure and toxicity
- Identify and develop new intervention and prevention strategies
Related work of the National Toxicology Program
In 2000, a group of independent experts convened by the NIEHS and the National Toxicology Program (NTP)housed at NIEHS, concluded that there was credible evidence that very low doses of certain hormone-like chemicals can harm the bodily functions of the animals tested.
The NTP evaluates endocrine disruptors, including pesticides, perfluorinated chemicalscompounds that can replace BPA on the market and the components of flame retardant to learn how they can affect body tissues such as the breast, uterus, fat cells, male reproductive system and liver. Additionally, they conduct laboratory studies that help them prioritize endocrine-disrupting chemicals for more in-depth toxicity testing.
NTP scientists are collaborating with researchers at the U.S. Environmental Protection Agency (EPA) to develop and validate integrated high-throughput testing strategies detect substances likely to disrupt endocrine functions by interacting with the hormones estrogens and androgens. Additionally, they created a comprehensive database from thousands of scientific studies on how different substances interact with hormones.
Multi-agency Toxic 21 The program, in which NIEHS participates, develops and applies new models and tools using robotics to predict the endocrine disrupting activity of environmental substances.
What did the NIEHS find?
NIEHS-supported research has discovered links between endocrine-disrupting chemicals and possible wellness consequences, as shown in the following examples:
- Attention. Attention Deficit/Hyperactivity Disorder (ADHD) is one of the most common childhood disorders, which can persist into adolescence and adulthood. Symptoms of ADHD include difficulty staying focused, paying attention, and controlling behavior. Researchers reported in JAMA that ordinary exposure to certain phthalates, as found in urine samples, was associated with ADHD-related behaviors in adolescence. THE drug DES may be linked to an increased risk of developing ADHD in the grandchildren of women who used it during pregnancy.
- Immunity. Children exposed to high levels of PFAS had a diminished immune response to vaccines.
- Metabolism. Long-term exposure to arsenic can disrupt metabolism, increasing the risk of diabetes and other metabolic disorders.
- Puberty. The chemicals in lavender oil and tea tree oil are potential endocrine disruptors. Researchers have found that persistent exposure to lavender oil products is associated with premature breast development in girls and abnormal breast development in boys.
- the reproduction. DES can cause epigenetic changes, altering the way genes are turned on and off in the reproductive organs of mice. The findings provide a possible explanation for how endocrine disruptors affect fertility and reproduction.
