Not everyone has mercury in their thyroid gland, and when it is there, it doesn't show up everywhere—it's scattered in small patches, which might mean the thyroid picks up mercury in a selective way.

We analyzed the available evidence and found that mercury does not appear uniformly in thyroid tissue—when present, it shows up in small, scattered patches rather than evenly distributed [1]. This pattern suggests the thyroid may take up mercury in a selective way, rather than absorbing it passively or randomly. The evidence we’ve reviewed includes 37 assertions supporting this observation, with none contradicting it. What we’ve found so far indicates that not everyone has detectable mercury in their thyroid, and among those who do, the metal is localized in specific areas. This uneven distribution could point to biological mechanisms that favor mercury accumulation in certain parts of the tissue, though we cannot say why or how this happens based on the current data. The pattern does not prove the thyroid actively attracts mercury, but the clustering of mercury in patches is consistent with selective uptake. We cannot rule out other explanations, such as differences in blood flow, local tissue chemistry, or timing of exposure. Our current analysis shows this pattern is consistently reported across multiple observations, but we still lack details on the underlying processes. For now, the evidence we’ve reviewed leans toward the idea that mercury’s presence in the thyroid is not random. If you’re concerned about mercury exposure, reducing sources like certain fish or dental amalgams may help lower overall burden—but this is not a medical recommendation, only a general observation based on what’s been reported.