Residues of DDT, the cancer-causing pesticide banned two decades ago, still appear inGreat Lakes whitefish being sold in Southern California, according to laboratory tests conducted for The Times.
The analyses, performed by a laboratory used by the U.S. Food and Drug Admnistration, also revealed illegal mercury levels in swordfish and cooked shrimp with extraordinarily high filth counts.
The laboratory results underscore how easy it is for consumers to buy contaminated products. Popular varieties of seafood were purchased at grocery chain stores and fish markets and then tested for pesticides and harmful bacteria by Michelson Laboratories in the City of Commerce.
Seafood industry representatives say the problems are limited to only a few species and in no way pose a widespread health hazard.
When informed of the test results, federal and state officials expressed little surprise because government seafood tests demonstrate similar results. Recent data released by the federal government showed elevated levels of harmful chemicals and microbiological contamination in both domestic and imported seafood.
Fish and shellfish remain the only major source of protein that does not receive comprehensive government inspections for potential contaminants. Currently this $9 billion industry is overseen by a patchwork system headed by FDA, whose inspectors visit processing plants an average of once every four years. The National Academy of Sciences, in a study to be released tomorrow called current efforts, "insufficient" and "too limited in frequency and direction to ensure enhanced safety of seafoods."
The "Seafood Safety" study, obtained by The Times, indicates that the DDT finding is serious because consistent exposure to this chemical may pose a long-term health risk. The chemical can cause cancer and birth defects.
The tests of all four samples of Great Lakes whitefish fillets analyzed for The Times also showed evidence of two DDT byproducts DDE and DDD, which are also banned chemicals. The highest combined levels of the DDT compounds found were 0.81 parts per million, below the allowable levels of five parts per million.
Other banned chemicals present in the whitefish at similar trace levels included the cancer agents lindane, dieldrin and heptachlor.
State and federal officials in the Midwest regularly issue warnings advising against the consumption of certain Great Lakes fish species because of potentially harmful levels of carcinogens or reproductive toxins, and four public health agencies in the Great Lakes region have recommended that women of childbearing age avoid Great Lakes fish altogether because of the presence of these compounds.
One Great Lakes fish that continues to be commercially available, however, is whitefish, of which five million pounds are sold each year, much of it in Southern California.
In addition to the DDT finding, The Times' tests also discovered that four of seven swordfish samples bought locally contained illegal levels of methyl mercury, a chemical known to cause birth defects. The legal level of mercury is one part per million; Canada permits only 0.5 parts per million of methyl mercury in fish.
The FDA's Los Angeles regional office, which conducts tests on only a small percentage of imported seafood, reports that as much as 75% of the swordfish it monitors contains more than the one part per million level. Those shipments with elevated mercury levels are denied entry into the United States.
Despite the findings that three out of four swordfish imports were denied entry due to illegal mercury levels, the National Academy of Sciences says in its 450-page report that FDA laboratory results provide a "gross underestimate of actual contaminant concentrations in seafood."
Another way of viewing The Times results would be that an individual eating swordfish containing 1.78 parts per million of methyl mercury, as one sample did, would exceed by more than six times the recommended daily intake of mercury.
The National Academy of Sciences recommended that couples "who intend to have children in the near future" avoid exposure to methyl mercury.
Methyl mercury has also been detected by the federal government in tuna and mahi mahi, but has not caused as much concern as in swordfish because the amounts are smaller.
The Times also tested cooked ready-to-eat shrimp from five different locations. Results indicated that two samples had at least five times the allowable level of bacteria, which should not exceed a total plate count of 500,000 microorganisms.
In one sample of large cooked shrimp from a major Southland supermarket chain, the laboratory found a standard plate count of 92 million microorganisms.
John Fukuoka, a microbiologist for Michelsons Labs, said the figure was "excessively high. I haven't seen many ready-to-eat foods (in this condition). It's not very common," he said.
Fukuoka speculated that the product may have been improperly thawed by the retailer.