Iodine is important for healthy thyroid function (see also here, here). Thyroid dysfunction has been associated with iodine toxicity (which can result from excessive consumption of kelp and thyroid gland-contaminated sausages).
PBDEs (flame retardant industrial chemicals) found in fish may disrupt thyroid function. An excess of deaths for disorders of the thyroid gland have been observed in poultry workers, perhaps due to chicken viruses and other pathogens. Processed meat consumption may be associated with thyroid cancer.
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