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Great Lakes Monitoring

Fish Indicators
Contaminants in Great Lakes Sport Fish Fillets

Benefits of Eating Great Lakes Fish

Children fishing from a dock
Children fishing
from a dock
Photo courtesy of ATSDR
Fish and shellfish are an important part of a healthy diet because they contain high-quality protein and other essential nutrients, are low in saturated fat, and contain omega-3 fatty acids. Fish is an integral part of every consumer's balanced diet. A well-balanced diet that includes a variety of fish and shellfish can contribute to heart health and children's proper growth and development. As with any food or health product, there are risks to consumption, but thanks to better scientific information and various public health and safety initiatives by the federal, state, tribal and provincial governments, citizens can and should feel comfortable consuming fish (Crawford, 2004).

Contaminants in Great Lakes Fish

Certain human-made organic chemicals present in water bodies such as the Great Lakes biologically accumulate (bioaccumulate) in organisms that live there. Even though these chemicals may be present in the water at only very low levels, through bioaccumulation, organisms such as phytoplankton can accumulate these toxic chemicals at much higher concentrations than are found in the water. As the phytoplankton is eaten by zooplankton and small fish, the toxic chemicals are further concentrated in the bodies of the zooplankton and the fish. This is repeated at each step of the food chain. This process of increasing concentration through the food chain is known as biomagnification.

Since the 1970's, there have been declines in many persistent bioaccumulative toxic (PBT) chemicals in the Great Lakes basin. However, PBT chemicals, because of their ability to bioaccumulate and persist in the environment, continue to restrict fish consumption in all five Great Lakes.

Fish Consumption Programs are well established in the Great Lakes. States, tribes, and the province of Ontario have extensive fish contaminant monitoring programs and issue advice to their residents about how much fish and which fish are safe to eat . This advice ranges from recommendations limiting consumption of specific sizes, species, and or water bodies to unlimited consumption of fish from various locations. Advice from these agencies to limit consumption of fish is mainly due to levels of PCBs, mercury, chlordane, dioxin, and toxaphene in the fish and are displayed in the graphic below.

Map showing contaminants causing fish consumption advisories in each lake

Great Lakes Fish Consumption Advisories

Fisherman aboard a charter fishing boat
 Fisherman aboard a charter fishing boat
Fishermen prepare fish on barbeque at the beach
 Fishermen prepare fish on barbeque at the beach
There are currently fish consumption advisories in all of the Great Lakes because of the presence of toxic contaminants in fish and there are certain fish - generally the larger, older, fattier types of fish - that susceptible populations should avoid eating. The states, territories, and Native American tribes (hereafter referred to as states) have primary responsibility for protecting residents from the health risks of eating contaminated fish and wildlife. If high concentrations of chemicals are found in local fish and wildlife, then a state may issue a consumption advisory for the general population, including recreational and subsistence fishers, as well as for sensitive subpopulations (such as pregnant women, nursing mothers, and children). Although there are advisories in the United States for a total of 39 chemical contaminants, most advisories have involved five primary contaminants: mercury, PCBs, chlordane, dioxins, and DDT. A consumption advisory may include recommendations to limit or avoid eating certain fish and wildlife species caught from specific water bodies or, in some cases, from specific water body types (e.g., all lakes). Similarly, in Canada, the provinces and territories have primary responsibility for issuing fish consumption advisories for their residents. States typically issue five major types of advisories and bans to protect both the general population and specific subpopulations. There are several domestic and binational programs and initiatives in place to reduce and eliminate the toxic substances in the lakes that lead to fish consumption advisories (USEPA 2004).

Health Effects of Eating Great Lakes Fish

The following are health effects associated with the five primary contaminants used to set fish advisories. For more information on the uses and history of these contaminants, please Click here.

Mercury - Mercury can combine with carbon to make organic mercury compounds. The most common one, methylmercury, is produced mainly by microscopic organisms in the water and soil. 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. (Ref: http://www.atsdr.cdc.gov/substances/ToxOrganSystems.asp)

Health problems caused by mercury depend on how much mercury has entered your body, how it entered your body, how long you have been exposed to it, and how your body responds to the mercury. People are at risk when they consume mercury-contaminated fish and when they are exposed to spilled mercury.

For fetuses, infants and children, the primary health effects of mercury are on neurological development. Even low levels of mercury exposure, which can result from mother's consumption of fish and shellfish that contain methylmercury, can adversely affect the brain and nervous system. Impacts on memory, attention, language and other skills have been found in children exposed to moderate levels in the womb. (Ref: http://epa.gov/mercury/health.htm)

PCBs - PCBs (Polychlorinated Biphenyls) have been demonstrated to cause a variety of adverse health effects in humans and wildlife. PCBs have been shown to cause cancer in animals, in addition to a number of serious non-cancer health effects in animals, including effects on the immune system, reproductive system, nervous system, endocrine system and other health effects. Studies in humans provide supportive evidence for potential carcinogenic and non-carcinogenic effects of PCBs. The different health effects of PCBs may be interrelated, as alterations in one system of the body may have significant implications for the other systems of the body. (Ref: http://www.epa.gov/pcb/effects.html)

DDT - (dichlorodiphenyltrichloroethane) Even though DDT has been banned since 1972, this pesticide can take more than 15 years to break down in our environment. Fish consumption advisories are in effect for DDT in many waterways including the Great Lakes ecosystem. Potential adverse health effects of large DDT consumption include: cancer, damage to the liver, temporary damage to the nervous system, reduced reproductive success, and damage to the reproductive system. (Ref: http://www.epa.gov/opptintr/pbt/ddt.htm)

Chlordane - Everyone in the United States has been exposed to low levels of chlordane due to its wide spread use as a pesticide. Chlordane remains in our food supply because it was commonly used on crops in the 1960's and 1970's. Fish consumption advisories for some species are in effect for chlordane in the Great Lakes ecosystem. Potential adverse health effects of large chlordane consumption include; cancer and may cause liver cancer, behavioral disorders in children if they were exposed before birth or while nursing, and harm to the endocrine system, nervous system, digestive system, and liver. (Ref: http://www.epa.gov/opptintr/pbt/chlordane.htm)

Dioxin - Because dioxins are widely distributed throughout the environment in low concentrations, are persistent and bioaccumulative, most people have detectable levels of dioxins in their tissues. This background exposure is likely to result in an increased risk of cancer and is uncomfortably close to levels that can cause subtle adverse non-cancer health effects in both animals and, to a more limited extent, in humans. In animals these effects include changes in hormone systems, alterations in fetal development, reduced reproductive capacity, and immunosuppression. Effects specifically observed in humans include changes in markers of early development and hormone levels. At much higher doses, dioxins can cause a serious skin disease in humans called chlordane. (Ref: http://www.epa.gov/opptintr/pbt/dioxins.htm)

All foods, including fish, contain some environmental contaminants. Federal government agencies restrict the sale of fish based on environmental contaminants in the edible portion of fish. When setting the acceptable level of a contaminant in commercial fish, federal governments take into account several factors in addition to potential health effects including: assumptions about how much fish people eat, the species consumed, where the fish are caught, and economic considerations.

The following are health effects associated with the five primary contaminants used to set fish advisories. For more information on the uses and history of these contaminants, please Click here.

Mercury - Mercury can combine with carbon to make organic mercury compounds. The most common one, methylmercury, is produced mainly by microscopic organisms in the water and soil. 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. (Ref: http://www.atsdr.cdc.gov/tfacts46.html)

Health problems caused by mercury depend on how much mercury has entered your body, how it entered your body, how long you have been exposed to it, and how your body responds to the mercury. People are at risk when they consume mercury-contaminated fish and when they are exposed to spilled mercury.

For fetuses, infants and children, the primary health effects of mercury are on neurological development. Even low levels of mercury exposure, which can result from mother's consumption of fish and shellfish that contain methylmercury, can adversely affect the brain and nervous system. Impacts on memory, attention, language and other skills have been found in children exposed to moderate levels in the womb. (Ref: http://epa.gov/mercury/health.htm)

PCBs - PCBs (Polychlorinated Biphenyls) have been demonstrated to cause a variety of adverse health effects in humans and wildlife. PCBs have been shown to cause cancer in animals, in addition to a number of serious non-cancer health effects in animals, including effects on the immune system, reproductive system, nervous system, endocrine system and other health effects. Studies in humans provide supportive evidence for potential carcinogenic and non-carcinogenic effects of PCBs. The different health effects of PCBs may be interrelated, as alterations in one system of the body may have significant implications for the other systems of the body. (Ref: http://www.epa.gov/pcb/effects.html)

DDT - (dichlorodiphenyltrichloroethane) Even though DDT has been banned since 1972, this pesticide can take more than 15 years to break down in our environment. Fish consumption advisories are in effect for DDT in many waterways including the Great Lakes ecosystem. Potential adverse health effects of large DDT consumption include: cancer, damage to the liver, temporary damage to the nervous system, reduced reproductive success, and damage to the reproductive system. (Ref: http://www.epa.gov/opptintr/pbt/ddt.htm)

Chlordane - Everyone in the United States has been exposed to low levels of chlordane due to its wide spread use as a pesticide. Chlordane remains in our food supply because it was commonly used on crops in the 1960's and 1970's. Fish consumption advisories for some species are in effect for chlordane in the Great Lakes ecosystem. Potential adverse health effects of large chlordane consumption include; cancer and may cause liver cancer, behavioral disorders in children if they were exposed before birth or while nursing, and harm to the endocrine system, nervous system, digestive system, and liver. (Ref: http://www.epa.gov/opptintr/pbt/chlordane.htm)

Dioxin - Because dioxins are widely distributed throughout the environment in low concentrations, are persistent and bioaccumulative, most people have detectable levels of dioxins in their tissues. This background exposure is likely to result in an increased risk of cancer and is uncomfortably close to levels that can cause subtle adverse non-cancer health effects in both animals and, to a more limited extent, in humans. In animals these effects include changes in hormone systems, alterations in fetal development, reduced reproductive capacity, and immunosuppression. Effects specifically observed in humans include changes in markers of early development and hormone levels. At much higher doses, dioxins can cause a serious skin disease in humans called chlordane. (Ref: http://www.epa.gov/opptintr/pbt/dioxins.htm)

Joint Advisory on Mercury in Fish

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. (Ref: http://epa.gov/waterscience/fishadvice/advice.html.

The Great Lakes Human Health Network

Great Lakes Human Health Network (Network) was established to improve the exchange of environmental-related health information across the Great Lakes basin. The Network was formed in December 2002 under the guidance of the Binational Executive Committee (BEC), a body comprised of senior Canadian and U.S. officials, to create a forum or mechanism to discuss human health issues directly related to Great Lakes water quality. The Network addresses health issues related to the state of the Great Lake basin ecosystem, including drinking water and recreational water quality and fish consumption.

The Network is a voluntary partnership of representatives of both U.S. and Canadian governments and their agencies whose purpose is to exchange information, facilitate communication and support the coordination of public health and environmental agencies. Network members will be able to return to their organizations and relay shared information to the communities they serve. The network is also designed to support the LaMP and Remedial Action Plan (RAP) processes. Currently, the Network is comprised of representatives from six federal government agencies, five tribal government agencies, eleven state and provincial government agencies, and one county government agency. Network membership continues to build.

Acknowledgements

Crawford, Lester, FDA, Fish is an Important Part of a Balanced Diet, March 2004.

U.S. EPA, Great Lakes National Program Office. Toxics in Top Predator Fish

U.S. EPA, Office of Water, National Listing of Fish Advisories.



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