2) A metallic element that is made naturally in our environment and is also made as a byproduct of industrial production, occurring most noticeably as fossil fuels, such as coal, pulp, paper, and waste are burned resulting in the emission of mercury. Mercury has become a health concern for many consumers due to the levels now being discovered in a variety of fish. As mercury is emitted from burned fuels, it is released to the air where it falls onto lakes, rivers, streams, and oceans, beginning a transformation, aided by bacteria, into becoming a toxic substance known as methyl mercury, a harmful neurotoxin. Thus, fish and various other types of water inhabitants (shellfish, waterfowl, birds, and other creatures) who feed on materials in the water begin to absorb the mercury into their bodies. Consequently, as consumers eat fish the methyl mercury is then absorbed into their organs, which if consumed in large quantities may be damaging to the brain and kidney, especially for developing fetuses of women during their childbearing age. Predatory fish that live longer and feed on other fish contain the largest levels of mercury, of which these species include shark, swordfish, king mackerel, and tile fish. Thus, the FDA warns pregnant women and those who may become pregnant to avoid the predatory fish, which contain the elevated levels of methyl mercury. Varieties of fish that are known for having low levels of methyl mercury are cod, haddock, pollock, salmon, sole, and tilapia. However, diets can also include consuming reduced amounts of fish such as canned fish, farm-raised fish, and shellfish that are also known to contain lower levels of methyl mercury.