Low Socioeconomic Status Raises Pregnant Women’s Risk of Exposure to Thyroid-Disrupting Chemicals

Exposure to some endocrine-disrupting chemicals (EDCs) that harm the thyroid gland has increased over the past 20 years among U.S. women of childbearing age and pregnant women, especially among those with lower social and economic status, according to a study presented at ENDO 2024. The researchers focused this study on women who may be particularly vulnerable to negative effects of EDCs on the thyroid: women in their childbearing years and pregnant women.

Researcher Cheng Han, MD, of the Boston University Chobanian & Avedisian School of Medicine analyzed data from the U.S. National Health and Nutrition Survey (NHANES) from 1999 to 2020 for 25,320 reproductive-age women and 2,525 pregnant women. He assessed trends over the past two decades in levels of multiple thyroid-disrupting chemicals in blood and urine samples. Statistical tests helped him to evaluate changes in EDC exposure over time and to identify the effect of socioeconomic status on this exposure.

Han found that exposure to many of the EDCs decreased for both groups of women over the 20-year study period. However, exposure to some thyroid-disrupting chemicals increased in that period. Both reproductive-age women and pregnant women had increased exposure to two types of polyaromatic hydrocarbons. Common sources of exposure to these chemicals include breathing cigarette smoke, wood smoke, or motor vehicle exhaust or eating grilled foods, according to the U.S. Centers for Disease Control and Prevention (CDC).

“Our research underscores the importance of addressing socioeconomic disparities in EDC exposure among women of reproductive age and pregnant women to mitigate potential adverse effects on thyroid health,” says senior author Elizabeth N. Pearce, MD, MSc, also of the Boston University Chobanian & Avedisian School of Medicine.

Han said that low-income women who were pregnant or of reproductive age had the greatest increase in exposure to thyroid-disrupting chemicals, especially polyaromatic hydrocarbons. “This increased exposure has the potential to worsen disparities in health outcomes among low-income people,” he says.