SACRAMENTO — PCBs, dangerous chemicals found in electric power equipment, are found in fish in Northern California waters and could threaten human health, according to a report released Wednesday by the Central Valley Regional Water Quality Control Board.
It said the Sacramento urban area appears to a major source of the pollution, and that an investigation is needed to track down locations where PBCs are escaping.
Fish containing PCBs have been found in the San Joaquin River near Vernalis, but investigators do not know whether the chemicals come from upstream or originate in the Stockton area.
"We intend to follow up on it," said Robert E. Fujii, a regional water board engineer who headed the team that drafted the report after three years of research. It was paid for by the state and the federal Environmental Protection Agency.
PCBs, or polychlorinated biphenyls, were used for many years in liquid insulation in electric power transformers. Use of them in manufacturing new equipment was halted in 1977, after animal lab tests linked them to cancer.
But the chemicals are still widely present in transformers, although many utility companies are phasing out equipment with PCBs.
Over the years, PCB leaks have caused significant pollution of the human food chain, necessitating the destruction of vast amounts of food.
"The stuff is slow to break down, and it persists for a very long time," Fujii said. He said PCBs from Northern California are carried into the Sacramento-San Joaquin River Delta and that the chemical has showed up in striped bass.
The investigation was based on levels of PCBs found in fish taken from Northern California streams.
Below Standard for Humans
The report said that in all but one sample, the PCB content in fish was below the level of two parts per million used by the federal Food and Drug Admnistration as the safety standard for human consumption.
However, in several cases they were higher than 0.5 ppm, the minimum guideline set by the National Academy of Sciences for maintaining the health of fish.