California regulators this week established new restrictions on a chemical — and suspected carcinogen — found in dozens of the state’s water systems.
The State Water Resources Control Board set a limit of no more than 5 parts per trillion of 1,2,3-Trichloropropane in drinking water.
The chemical is primarily used in industrial solvents and some fumigant pesticides, and a recent report said that 1,2,3-TCP was found in a majority of water systems in central California's San Joaquin Valley, one of the world's most productive agricultural regions.
Public water systems in California will be required to test for the presence of 1,2,3-TCP on a quarterly basis beginning next year. If the water supply exceeds the threshold over a rolling four-quarter average, authorities will be required notify customers and take corrective action.
The board said that at least one source in 103 water systems — serving more than 900,000 residents — showed 1,2,3-TCP levels above the new standard.
“1,2,3-TCP is not naturally occurring and too many Californians have been exposed to it for far too long, which is why it has been our top priority for standard-setting this year,” SWRCB Chairwoman Felicia Marcus said in a statement. "This standard will better protect public health and allow communities and the state to get on with the job of getting it out of our water supplies."