State officials are proposing a drinking water standard that would require Valley water systems to start removing a cancer-causing pesticide byproduct from tap water by 2018.
The chemical is 1, 2, 3-Trichloropropane, a fumigant additive that seeped into groundwater decades ago.
At a public workshop Thursday night at Woodward Park Regional Library in Fresno, officials with the State Water Resources Control Board outlined a proposed legal limit on the chemical, and sought feedback from the public. About 50 people attended the workshop, which was one of three held around the Valley.
TCP was added to the state’s list of chemicals known to cause cancer in 1999 but has remained unregulated. The chemical is most prevalent in Valley water, especially in Fresno, Kern and Tulare counties, but is also found elsewhere in the state, including Los Angeles County.
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The California Department of Public Health has a goal of keeping TCP to 0.7 parts per trillion, which is 1,000 times lower than the limit set for many other chemicals. Based on that goal, the department estimates that the lifetime risk of cancer would be one in a million people.
But the goal is just that – it’s not enforceable.
The board proposed a limit of 5 ppt, which would pose a cancer risk of less than 1 in 143,000 people. Research scientists estimate that almost 929,000 people known to have water contaminated with TCP levels above 5 ppt would be protected statewide.
We have to push the state to protect human health.
Dr. Jean Linder, local internal medicine physician
The standard is notably higher than the public health goal. Under state law, the legal limit has to be affordable and technologically feasible. The board recommends using granular activated carbon filters, which remove concentrations of TCP up to 5 ppt from water by trapping the chemical.
Conny Mitterhofer, a senior engineer at the water board’s division of drinking water, said other methods can detect TCP at levels lower than 5 ppt but those are not certified in California. She said the carbon method is simple, widely used and less expensive than other treatments.
TCP, a waste product from the plastic-making process, was in a widely used farm fumigant until the 1980s. It was discovered in drinking water during the 1990s.
Many cities, including Fresno, Clovis, Visalia and Bakersfield, have sued over the dangerous toxin. Dow Chemical and Shell Oil, which are defendants in the lawsuits, manufactured the chemical. Some communities settled with the manufacturers and already installed water treatment systems.
Treatment for all water systems identified by the water board is estimated to cost $34 million yearly. Not all water systems have been tested for TCP, because they were not required to, so costs will likely be higher.
The Governor’s Office set aside $5 million to individual homeowners and small water systems, and grants and loans are available to public water systems through the water board’s division of financial assistance.
At Thursday’s workshop, Medha Chandra, an organizer with the Pesticide Action Network, who said she’s concerned that the cost of treatment will be passed onto residents. She wants Shell and Dow Chemical to be held accountable.
Dr. Jean Linder, a local internal medicine physician, commended the board for proposing the 5 ppt regulation.
“The environment contributes to many cancers in our Valley,” she said. “We have to push the state to protect human health.”
Mitterhofer said the water board reviews legal chemical limits every five years, so the board could adopt a new standard if affordable technology allows them to detect levels lower than 5 ppt.
The water board will hold a 45-day public comment period this fall and public hearings in the winter. The standard is expected to be adopted by next spring and go into effect by summer 2017. Monitoring for TCP contamination would start in January 2018, but water purveyors could start treating it as soon as the standard is adopted.