Endocrine Disrupting Chemicals
*Originally published in March of 2021, most recently updated in August 2023
You’ve heard the term endocrine disruptor, but what exactly does this mean? And how do we avoid them?
Endocrine disruptors are chemicals that effect hormones in different ways. They can increase hormone levels, mimic hormones, and alter the reception of hormones in different areas of the body. This disruption in hormones negatively effects functions of the developmental, reproductive, immune, and neurological systems.
For example, studies have shown links between EDC exposure and the following health effects:
Abnormal breast development / increase in breast cancer risk
Epigenetic changes
EDCs have also been found to effect the following:
Reproduction
Breast cancer and prostate cancer
Neuroendocrinology
Cardiovascular endocrinology
Thyroid
Metabolism
Obesity
Exposure Of Endocrine Disrupting Chemicals
Routes of Exposure
We are exposed to various endocrine disruptors throughout our lifetime through our food and drink, what we put on our bodies, and in the air we breathe. This makes the safety assessment of individual EDCs quite difficult.
How Much Causes Harm
When it comes to EDCs, the dose does not necessarily make the poison. In fact, disorders from EDCs are believed to be the result of chronic low dose exposure. This is because our bodies are designed to detect tiny amounts of hormone changes.
Who Is At Risk
EDC exposure can be harmful to anyone, but is particularly harmful during critical development phases such as the fetal period, infancy, early childhood, and adolescence. Since the developing brain is very malleable, it is vulnerable to EDC exposure during critical periods of development.
Fetuses are believed to be the most at risk as EDCs cross the placenta and fetal blood-brain barrier. Studies show a negative association between prenatal EDC exposure and cognitive function, learning, memory, and IQ.
Adverse Health Effects of Endocrine Disruptors
Developmental Effects
EDCs may alter the hormone and receptor interaction in the brain and disrupt developmental processes. Exposure to endocrine disrupting chemicals effects normal development especially during critical developmental stages and creates transgenerational changes in behavior and gene expression. For example, EDCs that mimic estrogen effect the hypothalamus, which plays an important role in feeding behaviors. In this way, the EDC alters appetite and satiety neurons, thus modifying eating habits.
Neurotoxic Effects
Endocrine disruptors have neurotoxic effects that are indirectly related to their effects on hormones. EDCs can disrupt neurotransmitters such as dopamine, serotonin, norepinephrine, and glutamate which impacts behavior, cognition, learning, memory, and even metabolism. Additionally, EDCs are potentially associated with neurodegenerative disorders such as Parkinson's disease.
Immune Effects
EDCs effect the immune system by either suppressing it, increasing susceptibility to infections, or enhancing the immune system response. This can lead to inflammation, allergies, and autoimmunity. Studies suggest that EDC exposure impacts the gut microbiome and can increase the risk of metabolic diseases. The effect varies from person to person as gut microbiota varies among individuals.
Studies show the antibody response of childhood vaccinations is affected by EDC exposure during infancy.
Reproductive Effects
EDCs are associated with female infertility and subfertility. In one study, each one-unit increase in urinary concentrations of BPA was associated with a 23% increase in the odds of infertility. Bisphenol was found to cause spindle abnormalities and chromosome misalignment, even at very low doses. A study found that among women seeking infertifility care, higher urinary concentrations of DEHP metabolites were associated with significant decreases in antral follicle count. Studies suggest propylparaben is associated with diminished ovarian reserve. Exposure to high levels of methyl paraben and ethyl paraben was associated with reduced time to pregnancy.
7 Types of Endocrine Disrupting Chemicals
Polycyclic Aromatic Hydrocarbons (PAHs)
PAHs are primarily formed from the incomplete combustion of hydrocarbons. They are found not only in things like burning wood, fuels, cigarette smoke, and car exhaust, but also in petroleum based ingredients such as petrolatum and carbon black which are used in cosmetics and personal care products.
PAHs mimic steroid hormones and cross the placenta and fetal blood-brain barrier. Studies of maternal PAHs exposure show adverse effects on fetal growth and cognitive development, lower mental development at age 3, and lower IQ at age 5. It is believed that PAHs play a role in neurodevelopmental disorders such as ADHD and ASD.
Bisphenol A (“BPA”)
Bisphenol A (BPA) is found in plastics, food containers, food can linings, thermal paper (receipts), medical equipment, and other consumer goods.
Studies show plastic food storage and canned goods is a significant route of exposure to BPA. BPA leaches into the food and drink it packages and enters the bloodstream. Another route is through the skin from the handling of receipts. Thermal paper contains BPA coating that is heated when printed, resulting in relatively large exposure from handling receipts. Studies show elevated BPA levels in cashiers who handle receipts.
Effects of BPA range from DNA damage at low doses, to destroying cells at high doses. Animal and in vitro studies show an association between BPA exposure and breast cancer. Additionally, BPA is considered a class 2 reproductive toxin. BPA Alternatives, BPS and BPF, have estrogenic effects that are equal to or great than BPA.
Phthalates
Phthalates are widely used in cosmetics, pharmaceuticals, toys, personal care products and building materials. While not always included on ingredient labels, tests reveal phthalates hidden in fragrances and fragranced products.
In animal studies, phthalates exposure in utero is associated with decreased anogenital distance, infertility, decreased sperm count, undescended testes, and reproductive-tract malformations. Animal studies show phthalates primarily act as antiandrogens (counteract the effects of the male sex hormones) and impair testosterone production in Leydig cells.
In addition to disrupting the endocrine system, phthalates have adverse effects on the reproductive, neurodevelopment, and respiratory systems, as well as carcinogenic effects.
PFAS
Per- and polyfluoroalkyl substances (PFAS) are used in the manufacture of water-repellant fabrics, non-stick cookware, polishes, paint, wax, cleaning products, and firefighting foam. They can be found in water resistant cosmetics and apparel, nonstick cookware, microwave popcorn bags, floss, and even some mentrual underwear. REad about PFAS in menstrual underwear in this post from Mamavation.
Different types of PFAS include perfluorooctanoic acid (PFOA), polytetrafluoroethylene (PTFE) and GenX. In the US, PFOA was phased out by 2015, by PTFE and GenX are still allowed. PFAS are persistent in the environment and in our bodies.
Because of their persistent nature, PFAS have been found in drinking water and food. In 2020, Consumer Reports tested bottled water and found PFAS levels 43 of the 47 brands tested. In addition, PFAS were found in 1400 communities in 49 states according to research by the PFAS Project at Northeastern University in Boston and the Environmental Working Group (EWG).
Studies have linked PFAS to adverse health effects such as increased cholesterol, immune system effects, cancer, thyroid hormone disruption, and effects on infant birth weights. Animal studies indicate PFAS causes liver toxicity, disruption of immune and endocrine systems, neurobehavioral effects, neonatal toxicity and death, and tumors in multiple organ systems. PFAS exposure is associated with abnormal ovarian function but more studies are needed to confirm this.
Flame Retardants
Flame retardants are used in clothing, furniture, electronics, and building materials to reduce flammability of materials. In fact, children’s clothing is required by law in the US to contain flame retardants if it is not form fitting. (Learn more about safe children’s pajamas in this post).
Some flame retardants such as such as polybrominated diphenyl ethers (PBDE)s have been phased out due to their toxicity, environmental persistence, and bioaccumulation. Since then, organophosphate flame retardants (OPFRs) have been used as substitutes, Unfortunately OPFRs have adverse health effects also such as endocrine disruption, neurotoxicity, developmental toxicity, damage to the reproductive function, and carcinogenicity.
In animal studies, exposure to OPFRs shows altered thyroid function and change in liver weight. Human and zebra cell lines studies show that OPFRs alter the sex hormone balance by altering steroidogenesis or oestrogen metabolism.
Parabens
Parabens are routinely used as antimicrobial preservatives in everyday products from cosmetics, skincare, and household products to pharmaceuticals and food and beverage processing. Studies indicate that parabens mimic estrogen in the body and affect breast cell growth.
A Study from the University of California Berkeley found an earlier onset of puberty in girls associated with higher paraben levels. Learn more about parabens and common products that contain parabens in this blog post on parabens.
Chemical Sunscreens
Most sunscreens contain chemical UV filters because they go on clear and cost less. Chemical filters have been shown to mimic hormones, impacting the endocrine system. One study shows that certain UV filters interfere with sperm function.
Some commonly used chemical filters are oxybenzone, octinoxate, homosalate, avobenzone, and octocrylene. In 2019, The FDA warned about oxybenzone for its ability to effect hormones and increase absorption in the skin. Homosalate and octocrylene have been found to increase estrogenic effects on Michigan Cancer Foundation-7 (MCF-7) human breast cancer cell lines. Avobenzone produces many by-products in swimming pool water, some of which are known to be toxic (chlorinated phenols and acetophenones) and many others which the toxicity is unknown.
Learn more about how to choose safe sunscreen here.
How To Reduce Exposure To Endocrine Disruptors
Avoid plastic food storage
Avoid canned foods.
Avoid using non-stick pans that contain PFAS.
Avoid water repellent clothing.
Limit handling of receipts.
Avoid cosmetics and personal care products containing phthalates and parabens.
Do not use sunscreen with chemical uv filters.
Avoid fragranced products.
Filter drinking water.
Avoid clothing & furniture with flame retardants
Resources & References
[1] https://www.niehs.nih.gov/health/topics/agents/endocrine/index.cfm
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5393340/#:~:text=Exposure%20to%20endocrine%2Ddisrupting%20chemicals,disease%20susceptibility%20later%20in%20life.
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5761609/
[4] https://www.sciencedirect.com/science/article/pii/S0160412018303404
[5] https://www.ncbi.nlm.nih.gov/books/NBK453249/#:~:text=Male%20reproductive%20outcomes%20found%20in,in%20which%20the%20urethra%20does
[6]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6962585/
[7] https://onlinelibrary.wiley.com/doi/abs/10.1002/jat.3027
[8]https://ehp.niehs.nih.gov/doi/10.1289/ehp.1409200
[9]https://news.berkeley.edu/2018/12/03/prenatal-exposure-to-chemicals-in-personal-care-products-may-speed-puberty-in-girls/
[10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627825/#:~:text=Organophosphate%20flame%20retardants%20(OPFRs)%20are,materials%20%5B1%2C2%5D.
[11] https://pubmed.ncbi.nlm.nih.gov/28805477/
[12] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5744631/
[13] https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/homosalate
