As a general rule of thumb, IOWA FISH ARE SAFE TO EAT!

Every year, Iowa Department of Natural Resources (IDNR) fisheries biologists collect fish samples for laboratory analyses to determine the wholesomeness of Iowa fish for human consumption. A certified lab analyzes the samples and the results are compared to the fish consumption advisory protocol developed in 2005 by the Iowa Department of Public Health (IDPH) in cooperation with IDNR. Since 1977, nearly 800 fish tissue samples from over 200 sites on Iowa rivers and lakes have been collected and analyzed for contaminants. Click on the link to find out more about IDNR’s fish tissue monitoring program.

Prior to 2006, contaminant levels in Iowa fish were compared to “action levels” for mercury, PCBs, and chlordane published by the U.S. Food and Drug Administration (FDA). In recent years, many states have abandoned the use of the FDA action levels in favor of a more protective “risk-based” approach. Thus, in late 2005, the IDPH, in cooperation with IDNR, used U.S. Environmental Protection Agency’s (USEPA) guidance to develop a risk-based advisory system for Iowa that covers these contaminants.

The new IDNR/IDPH advisory protocol will result in the issuance of new consumption advisories for Iowa lakes and rivers and will result in modifications of Iowa’s existing consumption advisories at Cedar Lake and Ottumwa Lagoon. However, IDNR expects that the overall number of advisories will remain low and that Iowans can continue to catch and safely consume fish from the vast majority of Iowa’s streams, rivers, and lakes.

The decision to issue consumption advisories is based on results of annual fish contaminant monitoring conducted as part of the USEPA/IDNR Regional Ambient Fish Tissue (RAFT) monitoring program and other fish tissue contaminant monitoring programs in Iowa. Due to the large amount of variation in contaminant levels within fish populations, two consecutive samplings, exhibiting contaminant levels greater than IDNR/IDPH advisory levels, are needed to justify issuance of an advisory. Similarly, two consecutive samplings showing that contaminant levels are less than the IDNR/IDPH advisory levels are needed to remove an advisory. These consecutive samplings need not take place in consecutive years.

In order to implement the new IDNR/IDPH advisory protocol, the most recent five years of fish contaminant data (2000-2004) were reviewed to identify lakes and river reaches with samples in which contaminant levels exceeded advisory trigger levels. Based on this review, additional (follow-up) monitoring was conducted in 2005 to confirm the existence of these elevated levels of contaminants. Based on this information, four new consumption advisories were issued in 2006 and the consumption advisories at Cedar Lake and Ottumwa Lagoon were modified. Data collected as part of RAFT monitoring from 1994 through 2000 are being reviewed to identify other rivers and lakes that require additional monitoring to confirm the existence of elevated levels of contaminants.

Fish consumption advisories are issued wherever it is confirmed that advisory levels in the IDNR/IDPH protocol are exceeded.  Based on this new advisory protocol, IDNR and IDPH recommend the following:

LAKES:

• Cedar Bend Lake in Linn County: Eat only 1 meal/week of common carp due to elevated levels of PCBs.
• Cedar Lake in Cedar Rapids: Eat only 1 meal/week of common carp and channel catfish due to elevated levels of PCBs.
• Lake Geode in Henry County: Eat only 1 meal/week of largemouth bass due to elevated levels of mercury.
• Mormon Trail Lake in Adair County: Eat only 1 meal/week of largemouth bass due to elevated levels of mercury.
• Nine Eagles Lake in Decatur County: Eat only 1 meal/week of largemouth bass due to elevated levels of mercury.
• North Banner Lake in Warren County: Eat only 1 meal/week of largemouth bass due to elevated levels of mercury.
• South Banner Lake in Warren County: Eat only 1 meal/week of largemouth bass due to elevated levels of mercury.

• Pool 12 of the Mississippi River, which is the area between Lock and Dam 11 in Dubuque and Lock and Dam 12 at Bellevue in Jackson County: Eat only 1 meal/week of walleye, sauger, largemouth bass, smallmouth bass, white bass or northern pike due to elevated levels of mercury.
• The Cedar River from the Highway 218 bridge at Floyd (Floyd Co.) to the Iowa/Minnesota state line (39 mile stretch): Eat only 1 meal/week of smallmouth bass, walleye, and northern pike due to elevated levels of mercury.
• The Upper Iowa River from the State Highway 76 bridge in Allamakee County upstream to the County Road W-20 bridge in Winneshiek County, which is approximately 5.5 miles upriver (northwest) from Decorah (45 mile stretch): Eat only 1 meal/week of any species of fish due to elevated levels of mercury.
• The Volga River upstream of the Hwy C2W bridge at Volga in western Clayton County; including the Little Volga River and the North Branch Volga River: Eat only 1 meal/week of smallmouth bass due to elevated levels of mercury.

In addition to the advisories listed above, the Food and Drug Administration and the Environmental Protection Agency recommend that pregnant and nursing women, those planning to become pregnant and children 12 years of age (and younger) limit their consumption to 1 meal/week of larger size predator fish. These groups are potentially more susceptible to problems with mercury and larger size predator fish, such as walleye and bass, are more likely to have higher mercury concentrations.

The levels of most contaminants in Iowa fish, including chlordane and PCBs, continue to decrease as a result of USEPA’s banning of persistent pesticides and improved management in industrial and agricultural communities. However, levels of mercury in Iowa fish show no increase or decrease; the levels have been relatively stable since routine monitoring of fish contaminants began in the late 1970s. For more information on contaminant trends see the IDNR 2006 Fish Tissue Monitoring in Iowa fact sheet.

MERCURY: Mercury is often the contaminant of greatest concern in fish tissue, not only in Iowa, but worldwide. Mercury is a naturally occurring element in the environment and is also released into the air through industrial pollution. Mercury that falls from the air can accumulate in streams, rivers, lakes and the oceans. Fish can absorb mercury as they feed in these waters. How much mercury is too much in the fish we eat? The primary health concern for the general public is the consumption of fish containing methylmercury. Neurotoxicity is generally considered the health impact of greatest concern for dietary methylmercury intake. High-dose human exposure can result in sensory and motor impairment and other adverse impacts, up to and including death. High dose in utero exposure can cause mental retardation, cerebral palsy and deafness. There is also some evidence suggesting lower-dose exposures can have cardiovascular and immunological effects, but good epidemiological data is lacking. There is no argument that high doses of methylmercury can have severe health impacts. The question is whether relatively low level exposure, such as that incurred by fish consumption, presents more subtle risks such as cognitive disabilities, especially for children exposed to low levels in utero and though early childhood consumption of mother’s milk and fish. The IDPH, using USEPA guidance, determined that all fish containing less than 0.3 ppm mercury are safe to consume with no meal restriction. Consumption of up to 1 meal/week of fish containing between 0.3 and 1.0 ppm of mercury was safe and fish containing over 1.0 ppm of mercury should not be eaten (which is consistent with the current mercury FDA action level).

CHLORDANE: Chlordane is an organochlorine pesticide that was produced and sold in the United States from 1946 through 1987. Chlordane is resistant to breakdown in the environment and has a half-life of 10-20 years. Due to known toxicity and potential carcinogenicity, the USEPA canceled registration for all uses of chlordane on food crops in 1978. Before 1978, chlordane was used extensively as a lawn and garden pesticide and for the control of cutworms in corn. After restrictions were placed on usage in 1978, the primary use for chlordane was as a termaticide in building construction. Chlordane has been shown to cause liver cancer in mice and rats. USEPA classifies chlordane as a "probable" human carcinogen. In 1988, due to continued controversy over its use, the USEPA canceled the registration of all products containing chlordane. Use of existing supplies was allowed until April 15, 1988 when both the sale and use of technical chlordane were voluntarily suspended. The sale, purchase, and use of chlordane in Iowa were banned as of January 1, 1989. The IDPH, using USEPA guidance, determined that all fish containing less than 0.6 ppm chlordane are safe to consume with no meal restriction. Consumption of up to 1 meal/week of fish containing between 0.6 and 5.0 ppm of chlordane was safe and fish containing over 5.0 ppm of chlordane should not be eaten.

PCBs: Polychlorinated biphenyls (PCBs) are industrial chemicals that were manufactured in the United States from 1929 until 1977 under the trade name Aroclor. Currently, PCBs are not produced in the United States, but many products containing PCBs are still in service. Prior to 1977, PCBs were used in closed electrical systems such as capacitors and transformers. Before 1971, PCBs were used in a number of applications, including plasticizers, heat transfer fluids, hydraulic fluids, fluids in vacuum pumps and compressors, lubricants and wax extenders. Similar to chlordane, PCBs are also organochlorine compounds that are resistant to breakdown in the environment. PCBs tend to adsorb to sediments or other organic matter in aquatic environments. PCBs are highly lipophilic (fat soluble) and accumulate in tissues of fish and other aquatic organisms by a factor of 10,000 over concentrations found in ambient waters. PCBs are classified by USEPA as "probable" human carcinogens. The IDPH, using USEPA guidance, determined that all fish containing less than 0.2 ppm PCBs are safe to consume with no meal restriction. Consumption of up to 1 meal/week of fish containing between 0.2 and 2.0 ppm of PCBs was safe and fish containing over 2.0 ppm of PCBs should not be eaten (which is consistent with the current PCBs FDA action level).

For further information about the safety of eating fish, visit the Iowa Department of Public Health’s website, the Food and Drug Administration's website, and the Environmental Protection Agency's website.