Dropping levels of DDT found in fish in the Yakima River have led state health officials to drop advisories to limit meals from certain fish species pulled from the river. Recent data on PCBs, though, has resulted in new advice on eating common carp from the Yakima River.
Since 1993 the Department of Health has recommended people eat no more than one meal a week of bottom fish from the Yakima River to avoid DDT exposure. At that time, DDT levels in Yakima River bottom fish were among the highest reported in the nation. The advisory was for large-scale and bridgelip sucker, mountain whitefish, channel catfish, northern pikeminnow and common carp. DDT is a pesticide that was used in agriculture. Its use was banned in the 1970s.
A Department of Ecology study completed in 2007 found erosion control projects put in place by Yakima basin irrigators helped reduce DDT and its byproducts in fish from the Yakima River. The state health department evaluated the new data and determined the fish advisories based on DDT levels are no longer needed. The declining levels of DDT in resident bottom fish from the river, along with proper cleaning and cooking, allow people to eat them safely without limits.
"Fish is an excellent low-fat food and a great source of protein, vitamins and minerals," said State Health Officer Dr. Maxine Hayes. "It's important to include a variety of fish as part of a healthy diet. And while the news on DDT in Yakima River fish is good, we recently learned that PCBs in carp from the lower Yakima are high enough to warrant a meal limit. This is especially true for young children and women who might one day become pregnant.
"Yakima Valley irrigators really stepped up and deserve recognition for tackling a tough problem on one of Washington's great rivers," said Department of Ecology Director Jay Manning. "Like most watersheds, there's more work to be done, but this community has shown it can take on these types of challenges."
Data from the Ecology fish tissue study showed PCB levels in common carp in the lower section of the river indicate a need for a limit of one meal per week. This advisory includes carp taken from the lower Yakima River from the city of Prosser to the mouth of Richland.
PCB levels for other species sampled throughout the river system were below levels of health concern for people.
Meanwhile, the statewide mercury advisory for women who are or might become pregnant, nursing mothers and young children remains in effect. State health officials advise people in these groups not to eat northern pikeminnow and to limit largemouth and smallmouth bass to two meals per month.
PCBs and mercury are long-lasting chemicals that are found worldwide. They can cause behavior and learning deficits in children exposed in the womb. Banned since 1977, PCBs were used as insulating fluid in electrical transformers, lubricants and hydraulic fluids. Mercury occurs naturally but also comes from coal-fired electric plants and improper disposal of fluorescent bulbs, thermometers, thermostats and electrical switches.
To reduce exposure to PCBs in common carp from the Yakima River, the Department of Health recommends limiting consumption of common carp caught from Prosser to the mouth of the river near Richland to no more than one meal per week and to cook and clean fish to reduce contaminants. Remove the fat, skin and organs and allow fat to drip off during cooking. Filleting reduces PCB, but not mercury contamination.