Phthalate and BPA Plasticizers Disrupt Human Hormones

Plastics are composed of monomers held together with plasticizers. One of the most prevalent types of plasticizers are called phthalates.

Another type of plasticizer is better known: bisphenol A or BPA.

Phthalates have been found in drinking waters. This is a problem, because phthalate and bisphenol A plasticizers have been found to interfere with human hormones. Let’s examine some of the research.

Studies confirm phthalates interfere with hormones

A 2017 study from Taiwan’s National United University tested 279 adults from Taiwan, along with 79 minors. The researchers tested urine and blod for levels of phthalate metabolites. These included di-2-ethylhexyl phthalate (DEHP) and mono-ethylhexyl phthalate (MEHP).

The researchers found that phthalate levels influenced thyroid function and altered the stability of growth hormones. The researchers concluded:

“Our results are consistent with the hypothesis that exposure to phthalates influences thyroid function and growth hormone homeostasis.”

This is the classic scenario for hormone disruption. To disrupt the body’s natural flow of hormones means to interfere with hormone production in some way. This may result in increases in some hormones in some cases and decreases in other hormones.

Other plasticizers also disrupt hormones

Researchers from the University of Michigan have confirmed that common phthalate plasticizers DEHP, DBP and BPA disrupt human thyroid hormones associated with thyroid diseases.

The research compared and analyzed the metabolites from urine and serum thyroid levels of 1,346 adults and 329 adolescents. Higher di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and bisphenyl A (BPA) levels were associated with lower levels of the thyroid hormone metabolites of T4, free T3, total T3 and thyroglobin. Higher DEHP levels were associated with higher TSH levels, while higher BPA levels were associated with lower T3 and TSH levels.

The researchers found that lower T4 metabolite levels has the strongest association with higher phthalates. High DEHP levels were associated strongly with lower TSH levels, while BPA was associated with lower T4 and TSH levels.

This study, published in the scientific journal, Environmental Health Perspectives, was the first national human study confirming that BPA and other common plasticizers definitely disrupt hormones. Chemical industry advocates have been disputing the link between BPA and hormone disruption as coincidental. This research confirms previous research that led to the suspicion that these plasticizers disrupt hormone levels.

University of Michigan assistant professor and lead researcher, Dr. John Meeker, commented that those among the highest 20% of DEHP exposure had as high as 10% lower thyroid hormone levels.

DEHP, BPA and DBP are common among food packaging, water bottles, can linings and many other consumer goods.

REFERENCES:

Huang HB, Pan WH, Chang JW, Chiang HC, Guo YL, Jaakkola JJ, Huang PC. Does exposure to phthalates influence thyroid function and growth hormone homeostasis? The Taiwan Environmental Survey for Toxicants (TEST) 2013. Environ Res. 2017 Feb;153:63-72. doi: 10.1016/j.envres.2016.11.014.

Meeker JD, Ferguson KK. Relationship between Urinary Phthalate and Bisphenol A Concentrations and Serum Thyroid Measures in U.S. Adults and Adolescents from NHANES 2007-08. Environ Health Perspect. 2011 Jul 11.