Mercury exposure can permanently damage the brain, kidneys, and developing fetus. It can cause neurological deficits and changes in vision, hearing, and memory among all segments of the population. Women exposed to high levels of methyl-mercury during pregnancy have greater risks of having children with developmental problems, including mental retardation, lack of coordination, and delays in learning to walk and talk.

The Environmental Protection Agency (“EPA”) recently reported that approximately 630,000 newborns in the United States had unsafe amounts of mercury in their blood which had derived from contaminated maternal cord blood. The report suggests that mercury accumulates in umbilical cord blood at a level that is 1.7 times higher than that in the blood of the mother. This means that a woman whose mercury blood level is about 3.5 parts per billion could have a newborn with a mercury concentration greater than 5.8 parts per billion, the current safety limit for mercury. About one out of every six women of childbearing age has enough mercury in her blood to fit into that category and pose a threat to her fetus according to statistics presented by EPA researcher Dr. Kathryn Mahaffey, the author of the report.

This high mercury level among women of childbearing years was associated with fish consumption of species that contain high concentrations of mercury. These species include tilefish, shark, king mackerel, tuna, and swordfish. The Food and Drug Administration has issued warnings to pregnant women about the dangers of eating large predatory fish. The EPA has also recently advised the public about the high levels of another contaminant, polychlorinated biphenyl or PCB, in farmed salmon.

According to the EPA, other sources of mercury in the general population are emissions from coal-fired electric power plants, industrial boilers and burning hazardous waste. Because mercury can become airborne when emitted from these sources, it ultimately falls to the ground, where it enters the soil and groundwater. Microorganisms then convert part of the mercury to methyl-mercury, a toxic organic substance. The intake of methyl-mercury by small organisms that then get eaten by larger animals results in the contamination of the entire food chain. This is highlighted by the fact that at each stage, the amount of methyl-mercury becomes more concentrated.

Mercury also occurs in a metallic form as a shiny liquid and can form mercury salts when combined with chlorine, sulfur, or oxygen. Mercury metal is used in chlorine production, as well as in thermometers, dental fillings, and batteries.