Mercury is a potent neurotoxin that can harm the brain, spinal cord, kidneys and liver. It is especially dangerous to unborn babies and young children, whose brains and nervous system are still developing.

Mercury is a metal that is liquid at room temperature. It has had a wide variety of uses in industry and household and consumer products. At room temperature the liquid metal evaporates, creating an odorless vapor that is toxic to the lungs and nervous system. Items containing mercury should be disposed of at your community's household hazardous waste facility.


Mercury released from a variety of sources can get into the aquatic food chain. Mercury inappropriately sent to landfills is released as vapor or gets into water that runs through the landfill from precipitation. Mercury in items sent to incinerators is released to the atmosphere with the incinerators' emissions. Mercury from dental fillings gets into wastewater when fillings are made or removed if appropriate precautions are not taken at the dental office. The wastewater treatment plants do not have the means to remove the mercury, so it is released to the environment with the effluent from the plants. Coal fired power plants are the largest source of mercury emissions to the atmosphere in the United States because there is mercury in the coal before it is burned. Mercury in the atmosphere from mercury vapor or incineration falls back to Earth or is brought back with precipitation.

Once mercury is in water, microbes convert it to a more toxic form, methylmercury, which then accumulates and concentrates as it is passed up the food chain. Fish can have concentrations of mercury thousands of times higher than the surrounding water. Generally, the larger the fish and the higher up the food chain, the higher its mercury levels will be. People who consume more fish usually have higher mercury levels. Young children and women who are nursing or pregnant or who might get pregnant should be especially careful about eating fish because infants and young children are the most susceptible to mercury's neurotoxic effects. Studies have shown that children born with higher blood mercury levels from their mother's fish consumption have poorer scores on tests for language, attention and memory (Grandjean et al. Neurotoxicology & Teratology 19:417-428).