Study of Tainted Wells Defended : Contamination: Federal health officials acknowledge some errors in a report on the effects of toxic chemicals found at Space Ordnance Systems.

Federal health officials Thursday defended their conclusion that cancer-causing chemicals dumped at a defunct Santa Clarita Valley defense plant had seeped into nearby domestic water wells.

But the officials also acknowledged some errors in a report on the effects of toxic chemicals found at Space Ordnance Systems in secluded Sand Canyon, east of the Antelope Valley Freeway.

They said, for example, that the report inaccurately stated that three contaminated wells supplied water for human consumption, when in fact they were used to water livestock.

Officials of the Agency for Toxic Substances and Disease Registry repeated the principal conclusions of a draft study released in May. State and Los Angeles County health officials have challenged the federal agency’s report that certain chemicals from the defense plant had gotten into well water in the area.

The registry, an affiliate of the national Centers for Disease Control in Atlanta, held a public meeting at a Sand Canyon church Thursday night to collect public testimony for the final version of the report, which is expected to be completed in October.

Public Health Service Lt. Joe Hughart, an environmental health specialist, said contamination at SOS posed a very low risk of cancer to people who drank contaminated well water. The study does not deal with the probability of disease in individuals, he said.

SOS, a division of TransTechnology Corp., produced explosives and flares and was convicted of illegally storing and dumping hazardous chemicals at its Sand Canyon plant in 1986. The company was sold in May and is being relocated to Phoenix.

The controversy over SOS erupted last June shortly after the death of Charlotte Hercules Aitken, 23, of acute myelocytic leukemia, a rare form of the disease known as AML. Her stepfather, Robert Hercules, had died of kidney cancer four months earlier.

Aitken’s twin sister, Denise, died of AML at age 23 in 1986. Their half-brother, Christopher, 20, also died of AML in 1983.

The Hercules family had moved to Sand Canyon from Culver City in 1979 and lived about three-quarters of a mile from SOS. Relatives charged that toxic chemicals dumped at the plant were responsible for the diseases that claimed an entire family.

Diane Hercules, mother of Christopher and the twins, died in 1984 from an illness that eluded diagnosis. State health officials, in a report released in June, said the cause of Diane Hercules’ death might never be known, but suggested she also might have had AML and passed on the genetic flaw to her children.