Data show decrease in some contaminants

The Kansas Department of Health and Environment (KDHE) and the Kansas Department of Wildlife and Parks (KDWP) are issuing revised fish consumption advisories for 2009. The advisories identify species of fish that should be eaten in limited quantities or, in some cases, avoided altogether because of contamination found in tested fish.

The advisories include guidelines for mercury and polychlorinated biphenyls (PCBs) in fish, perchlorate in fish and other aquatic life, and lead and cadmium in shellfish. Data from most Kansas long-term monitoring sites show a decrease in PCB levels and no trend in mercury concentrations. PCBs have not been in use in the U.S. since the 1970s, and chlordane use was discontinued in 1988.

Chlordane levels have declined dramatically statewide, and PCB levels are expected to follow. PCBs and chlordane degrade slowly, so it takes decades for them to be completely removed from the environment, even after use is discontinued.

The two agencies recommend not eating specified fish or aquatic life from the following locations:

• the Kansas River from Lawrence (below Bowersock Dam) downstream to Eudora at the confluence of the Wakarusa River (Douglas and Leavenworth counties) for bottom-feeding fish (carp, blue catfish, channel catfish, flathead catfish, freshwater drum, bullheads, sturgeons, buffalos, carpsuckers and other sucker species) because of PCB levels;
• Horseshoe Lake located in units 22 and 23 of the Mined Lands Wildlife Area (Cherokee County) for all forms of aquatic life in addition to all fish because of perchlorate levels;
• the Spring River from the confluence of Center Creek to the Kansas/Oklahoma border (Cherokee County) for shellfish (mussels, clams, and crayfish) because of lead and cadmium levels; and
• Shoal Creek from the Missouri/Kansas border to Empire Lake (Cherokee County for shellfish because of lead and cadmium levels.

Additional recommendations include a limit of one 8-ounce serving per month, or twelve 8-ounce servings per year, on the consumption of bottom-feeding fish from the following locations due to PCBs:

• the Arkansas River from the Lincoln Street dam in Wichita downstream to the confluence with Cowskin Creek near Belle Plaine (Sedgwick and Sumner counties); and
• Cow Creek in Hutchinson and downstream to the confluence with the Arkansas River (Reno County).

Due to mercury contamination, a limit of one 8-ounce serving per week for adults or one 4-ounce serving per week for children (12 years or younger) of any species of fish is recommended from the following locations:

• the Little Arkansas River from the Main Street Bridge immediately west of Valley Center to the confluence with the Arkansas River in Wichita (Sedgwick County); and
• the main stem of the Blue River from U.S. 69 Highway to the Kansas/Missouri state line (Johnson County).

Kansas counties with current fish consumption advisories include Cherokee, Douglas, Johnson, Leavenworth, Reno, Sedgwick, and Sumner.

In 2004, the Environmental Protection Agency (EPA) issued a nationwide consumption advisory for locally caught fish based on nationwide average mercury levels in a variety of fish. Many states east of Kansas have mercury fish consumption advisories that include a mix of water-body specific and statewide advisories. EPA recommends that consumers limit consumption of any locally caught fish to not more than one 8-ounce meal per week. The advisory is designed to protect consumers in states lacking fish contaminant data. EPA further indicates that where there is better information, state advisories should take precedence.

Since 2004, KDHE has been collecting fish tissue samples from both lakes and streams. These samples are taken from bottom-feeding fish and from predatory fish (basses, crappie, walleye) in lakes. Mercury tends to accumulate in predatory fish to a greater extent than in bottom-feeding fish. Prior fish tissue contaminant monitoring efforts had largely focused on bottom-feeding fish and legacy organochlorine pesticides and other organic chemical contaminants (DDT, dieldrin, chlordane, PCBs, etc.).

Average mercury concentrations in Kansas fishes are clearly lower than nationwide averages. KDHE protocol requires use of the average tissue mercury level when conducting water body specific risk assessments. However, when considering the condition of the state’s water bodies as a whole, the median concentration is a better indicator of central tendency and is somewhat lower than the average.

Consumers of Kansas fish can safely eat at least two 8-ounce fish meals per week from any Kansas water body not under a specific KDHE/KDWP advisory. Data suggest higher levels of consumption are safe for most consumers. In about five years, data should be adequate for conducting individual risk assessments for the state's largest and/or most heavily-fished and harvested lakes, according to KDHE.

Women who are pregnant or nursing may wish to consult with their physicians about safe levels of fish consumption and mercury exposure. This sensitive group, and children under 12, should restrict their total mercury intake as related to both supermarket fish and locally-caught species.

Fish consumption advisories assess cancer risk levels using EPA methods. Cancer risk assessment is a method to determine the added increase in cancer levels in a population if fish in the advisory areas are consumed regularly over a 70-year period. Assessments that estimate the increased risk of cancer as greater than one in 100,000 are determined to be unacceptably high. Risk assessments for contaminants assessed as non-carcinogens (mercury, lead, cadmium) were based on 8-ounce serving size for adults and 4-ounce serving size for children nine to 18 years old.

Additional testing for contaminants in fish and other aquatic life will continue. Information on the Kansas Fish Tissue Contaminant Monitoring Program can be found online.

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