How Endocrine Disruptors Affect Your Thyroid and Immune System
Most conversations about endocrine disruptors, including most of what appears on this site, focus on reproductive health and fertility. That is where the evidence is strongest and where the consequences are most visible.
But the endocrine system is not just the reproductive system. It includes the thyroid, the adrenal glands, the pancreas and the immune system, all of which are regulated by hormones and all of which can be affected by chemicals that interfere with hormonal signalling. The Huberman Lab audience raised both the thyroid and immune questions specifically, and Dr Swan addressed them directly.
The Thyroid Connection
The thyroid gland produces hormones that regulate metabolism, energy, body temperature, heart rate and brain development. Thyroid hormones are particularly critical during fetal development and early childhood, when they play an irreplaceable role in neurological development.
Dr Swan confirmed directly in her Huberman Lab interview that there is a whole field studying the effect of endocrine disrupting chemicals on the thyroid system, and that there is substantial evidence that the effects are adverse. She noted this in the context of the broader picture of hormonal disruption rather than singling out specific chemicals for specific thyroid effects, but the research literature supports her assessment.
The chemicals most consistently associated with thyroid disruption in the published literature include PFAS, which interfere with thyroid hormone transport and metabolism. Several studies have found associations between PFAS exposure and altered thyroid hormone levels in adults, with some finding stronger effects in women. Perchlorate, a chemical found in some fertilisers and drinking water, competes with iodine for uptake by the thyroid gland, potentially reducing thyroid hormone production. Polybrominated diphenyl ethers, flame retardants once widely used in furniture and electronics that persist in dust and the environment, have been associated with thyroid disruption in multiple population studies.
The thyroid disruption research is an area where the human evidence is accumulating but causality is harder to establish than for reproductive effects. The associations are consistent across multiple independent research groups and are biologically plausible given what is known about how these chemicals interact with thyroid hormone pathways.
The Immune System Connection
Dr Swan raised a particularly thought-provoking point about the immune system in her interview. She referenced a long-running study in the Faroe Islands, where researchers studied people who ate locally caught fish containing high levels of persistent organic pollutants, a class of chemicals that includes older PFAS compounds and pesticides.
The study found that people with higher levels of these chemicals in their bodies showed measurably reduced immune responses. Dr Swan then raised the question that she said she does not know if anyone has yet studied specifically, whether widespread exposure to these chemicals across the general population has affected our collective immune response to vaccination. She described it as a really interesting question rather than a settled finding, which is the appropriate level of caution given the current state of the evidence.
What is more firmly established is that PFAS specifically have been associated with reduced antibody response to vaccines in children in multiple studies. Research published in the Journal of the American Medical Association in 2012 found that children with higher PFAS blood levels had lower antibody concentrations following routine childhood vaccinations. This finding has been replicated by other research groups and was a significant factor in the EPA's decision to move toward binding drinking water standards for PFAS in the United States.
What This Means Practically
The thyroid and immune findings reinforce rather than change the practical guidance that appears throughout this site. The chemicals most associated with thyroid and immune disruption, PFAS and persistent organic pollutants, are the same ones addressed on the Home and Living and Start Here pages.
Reducing PFAS exposure through water filtration, replacing non-stick cookware with cast iron or stainless steel, choosing PFAS free food packaging and personal care products, and eating organic produce where pesticide loads are highest are all steps that address the thyroid and immune concerns as directly as they address the fertility concerns the site focuses on primarily.
The same choices that protect reproductive health protect thyroid function and immune response. The chemicals are the same. The solutions are the same. The urgency is the same. The only difference is that fertility decline is visible in population statistics in a way that subtle thyroid and immune effects are not yet, which is why fertility has become the clearest signal in this area of research.
Related reading: our Start Here page introduces the three hidden threats in detail, our Home and Living page covers PFAS reduction at home, and the Dr Shanna Swan Expert Talk covers the Huberman Lab interview this article draws from.
Sources: Dr Shanna Swan, Huberman Lab interview | Grandjean et al., JAMA (2012) : PFAS and vaccine antibody response in children | Faroe Islands cohort studies on persistent organic pollutants and immune function | Zoeller et al., Endocrine Reviews (2012) : endocrine disruption and thyroid function