PFAS and Thyroid Disease: Current Evidence and Challenges

While PFAS chemicals have been linked to various types of cancer and immune dysfunction, growing research suggests a connection between PFAS exposure and thyroid disease.

The thyroid gland is a key regulator of metabolism, hormone balance, and overall bodily function. Disruptions to its normal operation can lead to hypothyroidism, hyperthyroidism, thyroid nodules, and even thyroid cancer. While some studies have shown PFAS exposure to interfere with thyroid hormone regulation, proving a direct link has been challenging due to multiple environmental and genetic factors that also contribute to thyroid disorders.

This article explores the scientific evidence, biological mechanisms, epidemiological studies, and ongoing legal challenges related to PFAS and thyroid disease.

PFAS exposure affects thyroid function in multiple ways, primarily through endocrine disruption, immune suppression, and metabolic interference.

PFAS chemicals mimic and interfere with the function of natural hormones.

• A 2021 study in Environmental Health Perspectives found that PFAS can bind to thyroid hormone receptors, altering their function and reducing hormone availability.
• PFAS have been shown to disrupt thyroid-stimulating hormone (TSH), leading to either hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid).

• PFAS interfere with iodine uptake, a crucial process for thyroid hormone production.
• Perchlorate, a known contaminant in drinking water, has been studied alongside PFAS, showing that these chemicals can compete with iodine in the thyroid gland, reducing hormone synthesis.

• A 2022 study published in the Journal of Endocrinology found that chronic PFAS exposure increases oxidative stress in thyroid tissues, leading to inflammation and potential tissue damage.
• PFAS are also linked to autoimmune thyroid diseases, including Hashimoto’s thyroiditis and Graves’ disease.

Several studies have investigated whether PFAS exposure is associated with a higher incidence of thyroid disease:

The National Health and Nutrition Examination Survey (NHANES) found that individuals with higher blood PFAS levels had a significantly increased risk of hypothyroidism.

Women were particularly affected, with a 36% greater likelihood of thyroid hormone disruption compared to those with lower PFAS exposure.

A large-scale study examining residents exposed to PFAS-contaminated drinking water from the DuPont plant found an elevated risk of thyroid dysfunction.

Higher PFAS concentrations in blood correlated with increased rates of thyroid nodules and hypothyroidism.

Military personnel and firefighters, who are frequently exposed to PFAS-containing firefighting foam (AFFF), showed a higher prevalence of thyroid disease, according to a 2023 study in Occupational Medicine.

The study suggested prolonged exposure may have cumulative effects on thyroid health.

While PFAS exposure may increase the risk of thyroid disease, there are many other factors that can contribute, making it difficult to attribute thyroid conditions solely to PFAS:

• Iodine deficiency or excess can significantly impact thyroid function.
• Goitrogens in certain foods, such as soy, cruciferous vegetables, and processed foods, may affect thyroid hormone levels.
• Chronic stress and obesity have been linked to increased thyroid hormone imbalances.

• Iodine deficiency or excess can significantly impact thyroid function.
• Goitrogens in certain foods, such as soy, cruciferous vegetables, and processed foods, may affect thyroid hormone levels.
• Chronic stress and obesity have been linked to increased thyroid hormone imbalances.

• Radiation exposure (such as from nuclear fallout or medical treatments) has been well-documented as a thyroid cancer risk.
• Pesticides, BPA, and heavy metals are other environmental toxins that may contribute to thyroid dysfunction.

As of 2025, there is a PFAS-related multi-district litigation in progress for individuals exposed to high concentrations of toxic PFAS through aqueous film-forming foam (AFFF) exposure. There is an effort to include thyroid disease as an accepted condition in the litigation; however at the present time, it is has yet to be accepted by the courts.

While thyroid disease is not currently a focus in the ongoing AFFF lawsuit, some law firms are taking select thyroid disease cases. However, these cases are challenging and require substantial supporting evidence due to the difficulty of proving a direct nexus between thyroid disease and PFAS exposure through AFFF.

Despite this ongoing research continues and may strengthen the legal standing of PFAS-induced thyroid disease cases in the future.

The potential connection between PFAS exposure and thyroid disease is a growing area of concern, particularly for individuals with high occupational or environmental exposure. While some epidemiological studies have demonstrated a link between PFAS and thyroid dysfunction, legal challenges and scientific uncertainties remain.

Military veterans, firefighters, and residents of PFAS-contaminated areas should continue to monitor thyroid function, stay informed about ongoing research, and explore legal options if they suspect PFAS contributed to their condition.