Mercury Level Builds in Fish Off Huntington Beach : Contaminants: Sanitation officials say that although the chemical can pose a risk of birth defects, the threat to consumers is minor.

Increasingly high concentrations of mercury have been found in a species of sand bass caught 5 miles off Huntington Beach, where Orange County’s treated sewage is discharged into the ocean.

County sanitation officials have detected the rising amounts of mercury in barred sand bass for the last five years during their annual marine monitoring. They said that although the poisonous chemical can pose a risk of birth defects, they believe that the threat to consumers is minor.

“We don’t believe a health risk exists; otherwise we would have suggested that the state take action,” said Blake Anderson, technical director of the Orange County Sanitation Districts. “The levels of mercury are marginally above the advisory level, and since sportfishermen are not present there, there isn’t a lot of consumption.”

Every day, millions of gallons of treated residential and industrial waste water is pumped into the ocean off Huntington Beach, including about 1.6 pounds of mercury a day, according to the sanitation agency’s annual report. The mercury probably comes from dental offices and hospital and home thermometers flushed down drains.

Even though the total mercury that Orange County discharges into the ocean has decreased, the amount found in barred sand bass has been increasing around the mouth of Orange County’s sewage pipeline, called an outfall.

A likely explanation is that sea bass populations have swelled dramatically because of an El Nino climactic condition almost 20 years ago, Anderson said. When fish live longer, they accumulate more of the dangerous contaminant in their tissues.

Other fish species that were tested did not contain excessive amounts of mercury, a toxic substance that attacks the brain and nervous system.

State health officials have not felt strongly enough about the risk to issue consumer warnings about fish caught near the outfall. But in general, they advise pregnant and nursing women to limit intake of fish to 1 pound per month when mercury exceeds 0.5 parts per million. The county’s 1990 tests of barred sand bass caught near the outfall detected 0.85 parts per million of mercury.

Barred sand bass is not a commercially sold fish. It is extremely popular with sports fishermen, but Anderson said they usually fish closer to shore than the point where the county’s waste water is discharged--5 miles off Brookhurst Street.

The larger and older the sand bass, the more mercury it could contain, since the chemical accumulates in tissues over the years. The state advisory especially pertains to fish over 15 inches, since they could contain more mercury.

Some local environmentalists have been critical of the county’s sanitation agency in recent years and have pushed for more thorough treatment of the waste. Anderson, however, said that increased treatment would not have a major effect on filtering out mercury and that the amount discharged is well within the state and federal government’s limits.

“We’ve already seen a drop in the mercury, and at this point it’s really unclear that it’s a health threat anyway,” he said.