DDT still present in SF Bay

Despite decades of attempting to eradicate the pesticide DDT from San Francisco Bay, the chemical is still poisoning fish and presenting a human health hazard.

The carcinogenic and nerve-damaging chemical was used to control mosquitoes and in agriculture before it was banned by the U.S. Environmental Protection Agency (EPA) in 1972, according to the San Jose Mercury News.

California officials discovered the pesticide-processing company United Heckathorn had discharged tons of the chemical into a bay canal from the late 1940s to 1966. The last cleanup project, which cost about $12 million, was ineffective. Recently recorded tests on fish-tissue samples showed the chemical was present at the same or higher levels than tests in 1994, even though the EPA dredged three tons of DDT from the canal in 1998.

The federal agency is launching a three-year study to determine why cleanup efforts are failing and will work with the city to raise awareness among subsistence anglers.