Study Warns of Toxic Chemical Off the Coast

A highly toxic chemical used to keep barnacles off boats was found in “alarmingly high” levels in mussels along the coasts of Orange, Los Angeles, San Diego and Contra Costa counties before it was banned for use on most boats last year, according to a state draft report.

Testing for tributyltin--a chemical used in paints to keep algae as well as barnacles off boat hulls--began in 1986 as part of a larger annual study by the state’s Mussel Watch, a program that uses mussels to test water quality in bays and along the coast.

A second round of samples taken by Mussel Watch in late 1986 and early 1987--the latest period for which data is available--showed “dramatic” increases of the compound in mussel tissue, according to the report, due for release next week.

“In 1986-87, alarmingly high traces of TBT in transplanted mussels were found at Richmond Inner Harbor, Monterey Bay, Port Hueneme, Marina del Rey, Los Angeles, Newport Bay and San Diego sites,” the report says.

Increases in the level of TBT included 219% at the Richmond Inner Harbor in Contra Costa County, 121% at the Newport Bay Upper Rhine Channel, 112% at the Consolidated Slip in Los Angeles and 96% at the North Harbor Drive commercial basin in San Diego Bay.

One TBT expert termed the Mussel Watch figures “interesting” but said the lag time in the samples fails to show the effects of a 1988 state ban of the compound for sport and pleasure boats, the major users of TBT-laced paints.

“I would say we have regulations on the books in California that should ameliorate the problem, and it’s going to take a number of years--at least 5 or 10 years--to see if it works,” said Edward D. Goldberg of the Scripps Institution of Oceanography in La Jolla.

The state banned the use of TBT paints on boats with hulls measuring 81 feet or less; exempted are larger boats and those with aluminum hulls.