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Chemical in sewage worries officials
Substance used in lawn products, household bug killers could harm streams, scientists say
By Berny Morson March 17, 2000 A chemical found in numerous lawn products and household bug killers could harm streams, environmental scientists believe.
Denver's Metro Wastewater Reclamation District has begun regular tests for the chemical, called diazanon, after it turned up four times in water discharged into the South Platte River.
Diazanon can be harmful to small children in concentrations as weak as 5 parts per billion, according to the Environmental Protection Agency. That level has never been reached in the Platte.
But 2 parts per billion of diazanon can kill insects and other tiny organisms that are a basic part of the food chain. That's equivalent to just four ounces of the chemical in the 160 million gallons of sewage that passes through Metro's treatment plant each day.
"It doesn't take much," said Metro water quality officer Todd Harris.
Furthermore, current treatment methods can't remove diazanon.
"What comes in goes out," Harris said.
Metro water was that toxic four times since 1997 in tests using a water flea called ceriodaphnia dubia as the canary in the coal mine. The fleas died most recently in May.
In January, the Colorado Health Department ordered Metro to test the effluent every two weeks using the flea.
Diazanon is used by professional turf growers to kill insects. But it is listed among ingredients in commercially available lawn products.
Diazanon is also found in products sold to kill roaches, ants and silverfish. Trade names include Basudin, Dazzel, Gardentox, Kayazol, Knox Out, Nucidol and Spectracide.
Steve Frank, the Metro spokesman, said the sudden surges of diazanon in the sewers may come from lawn professionals "who have gotten a little lax." But it could also come from people flushing household products down the drain after they clean out the garage, he said.
Metro is asking its 1.3 million customers to take leftover diazanon products to a municipal household toxic-waste disposal program.
Because Metro's effluent is diluted by the Platte, downstream concentrations have been too low to affect the food chain. Officials fear heavier concentrations if many people dump diazanon products down the drain.
Rocky Mountain News, CO
-- (Dee360Degree@aol.com), March 17, 2000