BPA and phthalates lower thyroid hormone levels

December 7, 2018


Previous posts have examined how goitrogens in peanuts, soy, cashews, etc.; "rocket fuel" in municipal water, pasteurized milk, etc.; bromate in bread products; fluoride; tea and coffee; low iron levels; thiocyanate in cigarette smoke; and pesticides, all inhibit iodine or thyroid hormone levels. We have seen how impaired thyroid function can result in obesity, impaired mental function, impaired memory and concentration, infertility, fatigue, neurological problems, and so much more. BPA and phthalates must also be added to the list of thyroid antagonists!


BPA and phthalates are already linked to endocrine/hormonal disruption. But in this confused  age, it appears only a few people really care about the dangers of chemically-induced androgyny! However, BPA and phthalates are also linked to breast and prostate cancers. This should matter to everyone. Why are so many people slow to make necessary changes? BPA and phthalates also inhibit thyroid function, and, among other things, this can greatly result in low motivation, impaired thinking - even retardation! 


BPA and phthalates are found in plastic bottles, fast food, the lining of canned foods, canned sodas and milk cartons, toys, cash register receipts, dental sealants, pizza boxes, baby bottles, water coolers, recycled paper, and much more. 


Researchers have demonstrated that contamination results even from cold or lukewarm plastic water bottles. And BPA is only one of scores of other endocrine disruptors in plastic.


Notice some studies linking BPA and phthalates to impaired thyroid function. How important it is to avoid all that lowers iodine and thyroid hormones (unless there is a medical issue), and make sure we are getting adequate iodine levels from raw dairy, organic cranberries, etc:


“BPA can mimic estrogen to interact with estrogen receptors α and β, leading to changes in cell proliferation, apoptosis, or migration and thereby, contributing to cancer development and progression…Moreover, BPA may also interact with other steroid receptors (such as androgen receptor) and plays a role in prostate cancer development…low binding affinity does not mean that the biological activity of BPA in human is negligible…BPA and its chlorinated derivatives also were shown to bind to thyroid hormone receptor (TR)…BPA also induced a profile of tumor aggressiveness in high-risk cells from breast cancer patients…”
(Medicine (Baltimore). 2015 Jan) 


“Phthalates are widely used chemicals, and human exposure is extensive. Recent studies have indicated that phthalates may have thyroid-disrupting properties…Our study showed negative associations between urinary phthalate concentrations and thyroid hormones, IGF-I, and growth in children…A normal thyroid function is important for growth and neurological development in children, and hypothyroidism in childhood is accompanied by growth retardation…A growing number of reports have indicated that environmental chemicals can interfere with thyroid function [reviewed by Boas et al. (2006)]. Both experimental and observational studies of wildlife and humans have suggested specific chemicals to have thyroid-disrupting properties, including recent investigations of phthalates. Phthalates are widely used industrial chemicals that are applied in a large variety of commercial products - for example, as plasticizers in toys, personal care products, and building materials, including wall paint (Sathyanarayana et al. 2008; Schettler 2006; Wormuth et al. 2006)… Most human studies have investigated reproductive effects of phthalate exposure, but recent studies also indicated thyroid-disrupting effects. Thus, serum levels of free thyroxine (T4) and total triiodothyronine (T3) in adult men were negatively associated with concentrations of metabolites of di(2-ethylhexyl) phthalate (DEHP) (Meeker et al. 2007). In pregnant women urinary concentrations of metabolites of di-n-butyl phthalate (DBP) were negatively correlated with serum levels of free and total T4 (Huang et al. 2007)…The mechanisms of thyroid-disruption may be multiple, because experimental studies have suggested that phthalates interfere with binding of T3 to transport proteins (Ishihara et al. 2003), interacting with the active T3 uptake at the plasma membrane (Shimada and Yamauchi 2004) or exerting antagonistic activity at the thyroid receptors (Shen et al. 2009)…”
(Environmental Health Perspectives, July 2010)


Large human study links phthalates, BPA and thyroid hormone levels…A link between chemicals called phthalates and thyroid hormone levels was confirmed by the University of Michigan in the first large-scale and nationally representative study of phthalates and BPA in relation to thyroid function in humans…The U-M School of Public Health study also reported suggestive findings consistent with a previously reported link between a chemical called bisphenol-A and thyroid hormone levels. BPA is best known for its use in certain plastic water bottles and in the linings of canned foods…greater concentrations of urinary phthalate metabolites and BPA were associated with greater impacts on serum thyroid measures, said John Meeker, assistant professor at U-M SPH and lead study author…meaning as urinary metabolite concentrations increased, serum levels of certain thyroid hormone levels decreased…The current study showed the strongest relationship between thyroid disruption and DEHP, a phthalate commonly used as a plasticizer. Research has shown that the primary exposure to DEHP is through diet…Thyroid hormones play an important role in many body functions, from reproduction to metabolism and energy balance…”
(Michigan News, University of Michigan, July 11, 2011)


“Bisphenol A (BPA), a monomer of polycarbonate plastics, has been shown to possess estrogenic properties and act as an agonist for the estrogen receptors. Although an epidemiologically based investigation has suggested that some chemicals could disrupt thyroid function in animals, the effects on thyroid hormone receptors (TRs) are unknown. We show here that BPA inhibits TR-mediated transcription by acting as an antagonist…BPA is detectable in our environment and is present in drinking water, canned goods, and even milk bottles. Recently, it was shown that BPA contaminates not only human plasma, but also fetal tissues…High doses of BPA may have reproductive toxicity and affect cellular development in rats and mice…Here we report that BPA can disturb thyroid hormone action. BPA reduced T3 binding to the nuclear TRs and recruited nuclear receptor corepressors (N-CoRs) to the TR, resulting in transcriptional inhibition…”
(The Journal of Clinical Endocrinology & Metabolism, Volume 87, Issue 11, 1 November 2002)


“Urinary Bisphenol A Concentration and Thyroid Function in Chinese Adults…Bisphenol A (BPA) is an endocrine disruptor that in animal studies can bind to the thyroid hormone receptor and affect thyroid function…Our results support previous reports of associations between BPA exposure and altered thyroid hormones in animal models and epidemiologic studies.”
(Epidemiology: March 2013 - Volume 24 - Issue 2)












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