Check if your seafood intake is within safe mercury limits.
Mercury enters waterways primarily from coal combustion and industrial processes. Bacteria convert it to methylmercury, which bioaccumulates up the food chain — large predatory fish like swordfish, shark, and king mackerel have the highest concentrations (0.7-1.4 ppm). The EPA's reference dose for methylmercury is 0.1 µg per kg body weight per day. For a 70 kg adult, that's 49 µg/week. Two servings of albacore tuna (340 g total at 0.35 ppm) delivers 119 µg — over twice the limit. Pregnant women face the greatest risk: methylmercury crosses the placenta and can impair fetal brain development. The FDA recommends pregnant women eat 2-3 servings per week of low-mercury fish (salmon, shrimp, pollock) but avoid high-mercury species entirely. Mercury has a half-life of 70-80 days in the human body, so reducing intake gradually lowers blood levels.