A Tire Chemical Is Messing With Pregnant Women's Thyroids
NonToxCo Research
Science & Safety Team · 4/7/2026
A chemical that comes from car tires is showing up in pregnant women's bodies and disrupting their thyroid hormones. It's called 6PPD-Q, and most people have never heard of it.
17 Chemicals, 764 Pregnant Women
A 2026 study in Environ Res tested 764 pregnant women at 8 to 16 weeks of gestation. Researchers measured 17 emerging endocrine-disrupting chemicals in their urine and five thyroid hormones in their blood.
Three chemicals stood out. 6PPD-Q (a tire rubber antioxidant byproduct), bisphenol S (BPS), and 1-H-benzotriazole were all linked to 5% higher TT3 levels. They also shifted the balance between T4 and T3 hormones in ways that signal thyroid disruption.
6PPD-Q Was the Worst Offender
When researchers looked at all 17 chemicals as a mixture, 6PPD-Q was the main driver of thyroid hormone changes. And they figured out how it works: oxidative stress. The chemical causes DNA damage (measured by a marker called 8-OHdG), which then disrupts thyroid function. Oxidative stress accounted for 33% of the effect on free T3 levels.
Your thyroid controls metabolism, brain development, and growth. During pregnancy, thyroid disruption can affect both mother and baby.
Where These Chemicals Come From
6PPD-Q forms when tire rubber breaks down and washes into waterways. BPS is the "safe" replacement for BPA in receipts and plastics. Benzotriazoles are in dishwasher detergents and anti-corrosion products.
How to Reduce Exposure
Filter your drinking water. Avoid handling thermal receipts. Choose BPS-free products. Look into non-toxic baby products to protect yourself and your baby during pregnancy.
Also see glass food storage for safer alternatives.