Great Lakes Monitoring

Fish Contaminants

Health Impacts of Eating Great Lakes Fish

Contaminant Concentrations in the Great Lakes

The Great Lakes Fish Monitoring Program monitors for a wide variety of contaminants in fish. Below are descriptions of some of the contaminants that are most used in fish advisories because of their effects on human health.

PCBs

What are PCBs?

Polychlrorinated biphenyls (PCBs) are mixtures of up to 209 individual chlorinated compounds (known as congeners). There are no known natural sources of PCBs. The manufacturing of PCBs was stopped in the U.S. in 1977 because of evidence that they build up in the environment and can cause harmful health effects. Products made before 1977 that may contain PCBs include old fluorescent lighting fixtures and electrical devices containing PCB capacitors, and old microscope and hydraulic oils.

What are the health effects associated with PCBs?

The most commonly observed health effects in people exposed to large amounts of PCBs are skin conditions such as acne and rashes. Studies in exposed workers have shown changes in blood and urine that may indicate liver damage. PCB exposures in the general population are not likely to result in skin and liver effects. Most of the studies of health effects of PCBs in the general population examined children of mothers who were exposed to PCBs.

DDT

What is DDT?

Dichlorodiphenyltrichloroethane (DDT) is a pesticide once widely used to control insects in agriculture and insects that carry diseases such as malaria. Its use in the U.S. was banned in 1972 because of damage to wildlife, but is still used in some countries.

What are the health effects associated with DDT?

DDT affects the nervous system. People who accidentally swallowed large amounts of DDT became excitable and had tremors and seizures. These effects went away after the exposure stopped. No effects were seen in people who took small daily doses of DDT by capsule for 18 months.

A study in humans showed that women who had high amounts of a form of DDE in their breast milk were unable to breast feed their babies for as long as women who had little DDE in the breast milk. Another study in humans showed that women who had high amounts of DDE in breast milk had an increased chance of having premature babies.

Chlordane

What is Chlordane?

Chlordane is a manufactured chemical that was used as a pesticide in the United States from 1948 to 1988. Chlordane is not a single chemical, but is actually a mixture of pure chlordane mixed with many related chemicals. Chlordane does not occur naturally in the environment. Because of concern about damage to the environment and harm to human health, the EPA banned all uses of chlordane in 1983 except to control termites. In 1988, EPA banned all uses.

What are the health effects associated with chlordane?

Chlordane affects the nervous system, the digestive system, and the liver in people and animals. Headaches, irritability, confusion, weakness, vision problems, vomiting, stomach cramps, diarrhea, and jaundice have occurred in people who breathed air containing high concentrations of chlordane or accidentally swallowed small amounts of chlordane. Large amounts of chlordane taken by mouth can cause convulsions and death in people.

Dieldrin

What is Dieldrin?

Dieldrin is a pesticide that was once used widely for crops like corn and cotton. Because of concerns about damage to the environment and potentially to human health, EPA banned all uses of dieldrin in 1974, except to control termites. In 1987, EPA banned all uses of dieldrin. This substance does not occur naturally in the environment.

What are the health effects associated with dieldrin?

People who intentionally or accidentally ingested large amounts of dieldrin suffered convulsions and some died. Health effects may also occur after a longer period of exposure to smaller amounts because these chemicals build up in the body.

Mercury

What is Mercury?

Mercury is a naturally occurring metal which has several forms. Metallic mercury is a shiny, silver-white, odorless liquid. If heated, it is a colorless, odorless gas. Mercury combines with other elements, such as chlorine, sulfur, or oxygen, to form inorganic mercury compounds or "salts," which are usually white powders or crystals. Mercury also combines with carbon to make organic mercury compounds. The most common compound, methylmercury, is produced mainly by microscopic organisms in the water and soil, which convert mercury to this more toxic form of methylmercury. More mercury in the environment can increase the amounts of methylmercury that these small organisms make. Methylmercury builds up in the tissues of fish. Larger and older fish tend to have the highest levels of mercury.

What are the health effects associated with mercury?

The nervous system is very sensitive to all forms of mercury. Methylmercury and metallic mercury vapors are more harmful than other forms of methylmercury, because more mercury in these forms reaches the brain. Exposure to high levels of metallic, inorganic, or organic mercury can permanently damage the brain, kidneys, and developing fetus. Effects on brain functioning may result in irritability, shyness, tremors, changes in vision or hearing, and memory problems.

In March of 2004, the Food and Drug Administration (FDA) and the Environmental Protection Agency announced their joint consumer advisory on methylmercury in fish and shellfish for reducing the exposure to high levels of mercury in women who may become pregnant, pregnant women, nursing mothers, and young children. This advisory unified the advice from both FDA and EPA and superceedes FDA’s and EPA’s 2001 advisories.

PBDEs

What are PBDEs?

Polybrominated diphenyl ethers (PBDEs) are flame-retardant chemicals that are added to plastics and foam products to make them difficult to burn. There are different kinds of PBDEs; some have only a few bromine atoms attached, while some have as many as ten bromine atoms attached to the central molecule.

PBDEs exist as mixtures of similar chemicals called congeners. Because they are mixed into plastics and foams rather than bound to them, PBDEs can leave the products that contain them and enter the environment.

What are the health effects associated with PBDEs?

There is no definite information on health effects of PBDEs in people. Rats and mice that ate food containing moderate amounts of PBDEs for a few days displayed effects on the thyroid gland. Those that ate smaller amounts for weeks or months displayed effects on the thyroid and the liver. Large differences in effects are observed between highly-brominated and less-brominated PBDEs in animal studies.

Preliminary evidence suggests that high concentrations of PBDEs may cause neurobehavioral alterations and affect the immune system in animals. In 2004, Chemtura, formerly Great Lakes Chemical Corporation and the largest producer of PBDEs in the Great Lakes Basin, voluntarily decided to cease production of two widely-used flame retardant chemicals, penta- and octa- polybrominated diphenyl ether.

Fish Contaminants

Health Impacts of Eating Great Lakes Fish

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