11 December 2001 23:27 [Source: ICIS news]
WASHINGTON (CNI)--The US Geological Survey (USGS) said Tuesday that raw data from a pilot study show that widely used herbicides have been detected in treated drinking water but at levels that meet national water quality safety standards.
The data collected by USGS, a unit of the US Department of Interior, will help the US Environmental Protection Agency (EPA) characterise human exposure to pesticides in drinking water, as required by the Food Quality Protection Act of 1996.
The survey was conducted in 1999 and 2000 and focused on drinking water derived from surface waters, USGS said. It looked for traces of 186 pesticides and break-down products of the chemicals in water sources in 12 states.
The survey found 116 chemicals in at least one sample of untreated or treated water, USGS said. Most often detected were the widely used herbicides atrazine, simazine, 2,4-D, tebuthiuron, metalaxyl, and acetochlor.
The herbicides were found in 36% to 96% of the 323 untreated water samples, and 19% to 96% of the 228 treated water samples, according to USGS.
Atrazine and simazine were detected at every site and in about 85% of all raw water samples.
However, USGS noted that it looked for the pesticides at very low concentrations that were 10-1000 times lower than EPA drinking water standards and health advisory levels.
Insecticides were detected less often, but p,p-DDE, azinphos-methyl, and carbofuran were found in about 5% of untreated water samples and in about 3% of treated water samples, USGS said.
Diazinon and chlorpyrifos were the most frequently detected insecticides in untreated water, but they were not found in treated water.
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