(HealthDay News) -- Mercury is an element found in the environment, from natural sources and as a byproduct of man-made pollution.
Mercury seeps into the soil and water, contaminating some of the foods people eat, the National Women's Health Information Center says.
Almost all types of shellfish and fish contain some mercury. Larger predator fish -- such as shark, king mackerel, tilefish and swordfish -- can harbor higher levels.
Pregnant women, women who are nursing, young children and women who might become pregnant should avoid consuming large amounts of mercury, which can harm the developing nervous systems of unborn and young children.
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