Mercury In Fish
ANSWERS
Mercury is a naturally occurring element in the atmosphere, water, and food. The majority of people are exposed to mercury through food. As they feed, fish absorb mercury from streams and oceans. This mercury is methylmercury, which is more toxic. It binds to the proteins in a person’s tissue (such as muscle). Food processing, preparation, and cooking methods do not significantly reduce mercury levels in fish.
Pregnant women – or, more accurately, their unborn children – are most vulnerable. Babies developing in the uterus (womb) appear to be the most vulnerable to mercury’s effects on their nervous systems. In the early years, mercury may slow their development. Although research is ongoing, pregnant women should be cautious about the types and amounts of fish they consume. Infants and young children should also be restricted from eating fish with high mercury levels.
Mercury exists in three forms in the environment: organic, inorganic, and metallic. The most dangerous form of mercury is organic mercury, specific methylmercury.
Methylmercury in fish is primarily derived from mercury in ocean sediment, converted to methylmercury by microorganisms. This organic form of mercury is absorbed by fish tissues via their gills while swimming and their digestive tracts while feeding.
Mercury levels vary from one fish species to the next. This is because of factors such as fish type, size, location, habitat, diet, and age. Predatory fish (those that eat other fish) are larger, and at the top of the food chain, so they contain more mercury.
Mercury poses a greater risk to unborn children. Mercury in fish can cause elevated mercury levels in the mother. This mercury can be passed on to her developing baby via the placenta.
During the third and fourth months of pregnancy, the fetus appears to be most vulnerable to the effects of mercury. The effects on the brain and nervous system may not be apparent until developmental milestones like walking and talking are delayed. Memory, language, and attention span may all suffer as a result.
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