Citing an unacceptable cancer risk, the South Coast Air Quality Management District has denied a permit application by Plato Products Inc. to operate its Glendora metal plating plant.
The firm, which has operated under temporary permits since 1984, is emitting a carcinogenic form of chromium at a concentration 30% above AQMD standards, agency spokesman Ron Ketcham said.
"It's not that far off, but it's not within our guidelines," Ketcham said. "There's not a health risk to the community on a short-term basis, but we are concerned about chronic long-term health effects."
Plato officials, who were informed of the denial Tuesday, said they will probably seek a temporary variance until they can develop more effective air pollution control equipment.
The company, which has been under fire from neighbors for a range of health-related complaints almost since it began operating in Glendora, has no intention of closing the plant, President George Kent said.
"This is a technical problem that has to be answered with technical answers," Kent said.
The denial stemmed from a July 29 test of air pollution control equipment at the plant, just across the city line from San Dimas at 2120 Allen Ave.
The pollution equipment, which the air quality district had ordered the firm to install as a prerequisite for approving the permit, was found to reduce emissions of hexavalent chromium at only a 59% efficiency rate, AQMD officials said. A rate higher than 90% had been expected, they said.
The result is that chromium was emitted from the plant in quantities of .00009 micrograms per cubic meter at the point of greatest concentration, Ketcham said.
Such quantities could cause 13 cancer cases per million people over a 70-year period, he said. AQMD policy is to limit such risks to one case per million people. However, if a firm attempts to control the problem with the best available technology, a risk of 10 cases per million is considered acceptable, Ketcham said.
"We believe the (air pollution equipment) can perform at higher than 59% efficiency," he said. "If that's done and they drive the risk down below 10 in a million, then they stand to be permittable."
Jeff Schenkel, a San Dimas resident and a leading critic of the plant, described the permit rejection as the most significant event in his three-year fight to close Plato.
"The AQMD did the only thing that was right," said Schenkel, a former information officer for the air quality district. "This was something that had to happen. The only safe solution is to shut down that chrome plating operation at that location."
The firm, on a one-acre site next to Arma J. Shull Elementary School in San Dimas, first encountered problems in 1984 when Schenkel and a committee of parents began complaining that chemical smells from the plant were endangering the 500 grade-school students nearby.
Although tests by the South Coast Air Quality Management District found no evidence that toxic fumes were being released, the air quality district did order Plato to upgrade its air pollution control equipment earlier this year, AQMD officials said.
In addition, officials said, Plato agreed voluntarily to improve several warning mechanisms designed to mitigate the chance of an accident.
Meanwhile, Schenkel and the citizens group persisted and, with the support of San Dimas city officials, persuaded the Los Angeles County district attorney's office to seek an investigation in November, 1985.
Conducted by the county Sanitation Districts, the investigation concluded that the company was discharging metal-contaminated waste water in concentrations two to three times greater than permitted under county law.
A Los Angeles Municipal Court judge fined Plato $27,500 last January after the firm pleaded no contest to 10 misdemeanor counts of dumping the toxic waste into county sewers.
Most recently, the company became the target of a county investigation to determine whether emissions from the plant could have caused a series of miscarriages among women living nearby.
In June, three women living on the 700 block of Groveton Avenue in San Dimas reported six miscarriages among them over the last two years, according to officials for the county Department of Health Services.
Although county health officials stressed that a direct connection between the miscarriages and the Plato plant would be difficult to prove, an investigation was launched to see whether other women in the vicinity had suffered similar prenatal problems.
This inquiry, still in progress, will also seek evidence of any other health problems, ranging from headaches to nausea, that could be connected to Plato's metal plating operation, said Paul Papanek, chief of the health department's toxics and epidemiology program.
Plato officials said such "high-profile" publicity was partly responsible for AQMD's decision to deny their application for an operating permit. They said their operation was more effectively controlled than most in the metal plating industry.
"We've been in a very high- profile situation, and for that reason we are probably getting very high-profile attention," said James E. Good, the attorney representing Plato. "We really feel we have made such an absolutely strong effort on this thing. If there is an extra measure to be taken, we're going to make a run at it."