The state is warning people not to eat any bottom-feeding fish caught in the Arkansas River below the Lincoln Street Dam in Wichita.
In past years, health officials warned anglers to limit the amount of fish they eat from the Arkansas River to one meal a month.
However, the level of PCBs found in the fish has increased, prompting the new warning.
The advisories are issued by the Kansas Department of Health and Environment and the Kansas Department of Wildlife and Parks.
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The advisory in Wichita is on the Arkansas River, from the Lincoln Street dam downstream to the confluence with Cowskin Creek near Belle Plaine.
This spot is one of six areas in Kansas where officials say the fish are unsafe to eat.
Officials also are warning residents to limit the amount of fish they consume from two other places, including the Little Arkansas River in Wichita.
The advisory recommends restricting consumption of any type of fish caught in the Little Arkansas River to just one meal per month. The area included in the advisory is from the Main Street Bridge immediately west of Valley Center to the confluence with the Arkansas River.
The primary contaminants in the Arkansas River are PCBs, which stand for polychlorinated biphenyls. PCBs come from electrical transformers and capacitors.
Children exposed to PCBs in the womb experience loss of muscle tone, weakened reflexes and other deficiencies that diminish with age. PCB exposure in adults has been connected to liver, skin, brain and breast cancers.
Fish in the Little Arkansas River contain both PCBs and mercury. Mercury can come from coal-fired power plants and other industrial processes. Babies who were exposed to mercury in the womb are at risk for adverse neurodevelopmental effects.
In comparison with last year's report, 2011 data shows no clear increasing or decreasing trends of mercury concentration in fish, said Kristi Pankratz, director of communications for the Kansas Department of Health and Environment.
In the southeast part of the state, where lead was once mined, the fish are contaminated with lead and cadmium. Pankratz said fish get contaminated when they absorb toxins through their skin and gills. Game species, like largemouth bass, often have more concentrated toxins from eating bottom-feeding fish.