Exposure to environmental chemicals linked to thyroid: Study

A study led by Brigham and Women’s Hospital, a founding member of the Mass General Brigham Healthcare System, uncovers multiple links between the presence of phenol biomarkers and altered thyroid hormone levels in women seeking fertility treatment. Their findings, which were published in the journal Toxics, reveal new insights into how environmental toxins and lifestyle decisions can affect reproductive health.

“Many women these days experience thyroid problems. Therefore, we aimed to identify some predictors of thyroid hormone levels to help women improve their health,” said senior author Lydia Minguez-Alarcon. said Ph.D., MPH, assistant professor at Harvard. A reproductive epidemiologist in the Channing Division of Network Medicine, Brigham Medical School, and co-investigator of the Environment and Reproductive Health (EARTH) study.

“In this context, a woman’s health is far more important than not only her well-being, but also her fertility and her knowledge of the risks.” Repeated exposure to specific phenol chemicals found in everyday items such as toys, sunscreen, dental products, food packaging and food preservatives can disrupt the hormonal balance within the body, leading to adverse health effects. Previous studies have evaluated these individual chemicals and their effects on the thyroid. However, the combined effect of these multiple phenols on the endocrine system, particularly with regard to female fertility, is not yet fully understood.

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Fertility depends crucially on maintaining a stable harmony of hormones within the body. Disruption at these levels can occur from external sources, particularly exposure to environmental hazards. The Brigham researchers sought to assess the effects of some of the most common environmental chemicals that have been shown to affect thyroid hormones in animal models.

Their study looked at 339 women seeking care at a fertility clinic. The team evaluated urine concentrations for phenol biomarkers and serum samples for molecular markers of thyroid function and thyroid autoimmunity. Various statistical methods were used to measure the combined effect of these biomarkers on thyroid levels.

By evaluating simultaneous combinations of chemicals, the researchers were able to more accurately capture real-world effects because humans are exposed to hundreds of chemicals at the same time, not one by one. The researchers observed that the presence of bisphenol A, methylparaben and triclosan in the urine was also associated with altered thyroid hormone levels, and some of them were indicative of thyroid diseases, including hypothyroidism. All of these phenols can be found in consumer products regulated by the United States Food and Drug Administration.

The researchers acknowledge that some of their measured relationships differ from findings in previous publications. This may be due to different study populations, phenol biomarker concentrations, or other phenols that were not measured in this study. These tests should be repeated in future studies and the long-term consequences of altered thyroid function should be considered.

“This study specifically focused on women whose fertility is sub-optimal, who have been shown to be at higher risk for thyroid disease,” Mingüez-Alarcon said. “In previous research with the same study team (Earth), we found that women with altered thyroid hormones had lower ovarian reserve, measured as a decrease in antral follicle count. Thus, while further research is needed to confirm these results, While more longitudinal studies will be needed, fluctuating thyroid hormone levels may be important for maintaining the fertility of critical preventable women.”