Evidence on the human health effects of low-level methylmercury exposure

Summary

This consensus review summarizes the human health-effect literature on low-level methylmercury exposure — the form of mercury delivered by dietary fish consumption. The authors evaluate evidence on neurodevelopmental, cardiovascular, neurological, and immunological endpoints across multiple populations and exposure ranges. Their conclusions are nuanced: childhood neurodevelopmental endpoints (subtle decrements in cognitive and motor performance in cohorts with prenatal exposure above background) are the most consistently supported across cohort studies; adult cardiovascular endpoints show much weaker and less consistent evidence; mercury's interaction with the omega-3 benefits of fish consumption complicates the simple dose-response picture for both endpoints. The review distinguishes high-mercury species (tilefish, swordfish, large tuna, shark, king mackerel — to be limited especially in pregnancy) from low-mercury species (small pelagics including sardines, anchovies, salmon — which deliver omega-3 benefits with low mercury exposure). The paper is widely cited in regulatory mercury-exposure guidance.