Yielding to complaints from water utilities, state health officials have agreed to more lenient drinking water standards for two suspected cancer-causing chemicals than they proposed last year.
Instead of a limit of 2 parts per billion parts of water for perchloroethylene, the Department of Health Services will set the standard at 5 p.p.b., according to David Spath, senior sanitary engineer with the department's public water supply branch.
Rather than limiting dibromochloropropane levels to .1 p.p.b., as originally proposed, Spath said the department will adopt a .2 p.p.b. standard for the pesticide.
Spath said the changes will put the state in step with the U.S. Environmental Protection Agency, which is expected to set the same limits on the chemicals.
He said health officials concluded that the changes are justified because the stricter limits would add little health protection but impose much higher costs.
The decision is "sensible," said Duane Georgeson, assistant general manager for water with the Los Angeles Department of Water & Power, which draws part of its water from PCE-laced wells.
It is "reasonable for the state to utilize EPA standards unless there's a compelling reason to do something different," Georgeson said.
But Patty Prickett, head of Citizens for Safe Drinking Water, a Los Angeles-based environmental group, blasted the Health Department's decision as "business as usual. . . . They've really wimped out here."
Limits on 12 other compounds--including benzene, xylenes and trichloroethylene--will not be changed from numbers proposed last year, according to Spath. He said these standards probably will take effect in February, followed in a month or so by the PCE and DBCP limits.
The state's record in controlling toxics in water has come under attack by some environmentalists and legislators. In a dramatic show of dissatisfaction, lawmakers last summer provided the agency's water supply branch with only enough funds to operate half the fiscal year that ends next June 30.
When the funds were not restored, department officials ordered the water branch closed and its employees reassigned, effective this week. Negotiations are under way between the department and lawmakers to end the stalemate.
According to state health officials, PCE has seeped into more water supply wells in California than any other industrial chemical. More than 25 San Fernando Valley wells, operated by Los Angeles, Burbank and Glendale, are affected, along with San Gabriel Valley wells pumped by the San Gabriel Valley Water Co., Suburban Water Systems and other utilities there.
A solvent widely used to degrease metal and dry-clean clothes, PCE is regarded by many experts as a probable but not very potent carcinogen.
DBCP is a banned pesticide that has tainted scores of water supply wells in the San Joaquin Valley and agricultural areas of Riverside and San Bernardino counties. Used to kill root-eating nematode worms, DBCP was taken off the market after male workers who made it began becoming sterile. At the low levels found in drinking water, it is suspected to pose a long-term cancer risk.
The state has no legal limits for PCE or DBCP in drinking water. But it has observed advisory standards, or "action levels," of 4 p.p.b. for PCE and 1 p.p.b. for DBCP.
Using theoretical estimates of cancer risk, Spath said the difference between a PCE standard of 2 p.p.b. and 5 p.p.b. amounts to less than one additional case of cancer over a period of 70 years.
He said about 490,000 Californians drink water containing more than 2 p.p.b. of PCE. Were the limit set at 2 p.p.b., about 2.74 cases of cancer theoretically would be averted over 70 years.
About 169,000 people drink water containing more than 5 p.p.b. With the limit at 5 p.p.b., 2.26 cancers theoretically would be averted over 70 years.
Water suppliers and their customers will save at least $5 million over 25 years by adoption of the 5-p.p.b. limit, state health officials estimate.
The theoretical risks of DBCP are considerably higher.
According to Spath, water of about 240,000 Californians contains DBCP levels exceeding .1 p.p.b. If the standard were set there, 163 additional cancer cases theoretically would be averted over 70 years, he said.
About 185,000 people drink water above .2 p.p.b. With the standard set there, 158 cancers theoretically will be prevented--five fewer than at the stricter standard.
The cost savings to utilities will be at least $10 million to $20 million over 25 years, according to Spath.
Even now, with only an advisory standard, utilities have coped with PCE problems by shutting down the most polluted wells and mixing water from less polluted wells with water from other sources, including surface water from sources such as the Owens Valley, the state water project and the Colorado River. Blending would have continued under a 2 p.p.b. limit, but eventually more wells would be idled.