FDA officials defended the agency’s method, saying that its tests showed unequivocally that seafood from the Gulf was safe to eat and should be returned to the market place.
A primary factor in the limit the FDA set on cancer-causing PAHs — polycyclic aromatic hydrocarbons — in Gulf seafood was the agency’s estimate of how much seafood people eat.
For the Gulf spill, the FDA assumed an adult eats about 3 pounds of fish per month, and about 1.6 pounds total of shrimp, crabs and oysters. Such consumption rates offer a built in-safety net, the FDA says, because the agency believes only 10 percent of the people in the U.S. eat that much seafood in a month.
The agency is allowing much higher PAH levels in shrimp, crabs and oysters based on the assumption that people eat more fish than the other types of seafood.
“What’s really reassuring, to keep this in context, there hasn’t been a sample collected yet above Levels of Concern,” said Don Kraemer, a senior FDA official overseeing the seafood testing program.
Dr. Gina Solomon, a University of California toxicologist, member of the U.S. Environmental Protection Agency's science advisory board, and senior scientist for the Natural Resources Defense Council, said the FDA’s approach leaves people who like shellfish more vulnerable.
“The FDA’s allowable level of cancer-causing PAHs for Gulf shrimp is about four times higher than for fish, and is far higher than levels that have been allowed for human consumption after previous oil spills,” Solomon said. “These levels are not likely to cause immediate health threats, but for people who like shrimp, these contaminants could pose a significant health problem over time.”
The assumption that people eat more fish than shrimp made a difference in Florida, where all nine of the shrimp samples tested before Florida waters reopened to commercial shrimping were double the level that would have triggered more testing for fish.
The FDA’s higher “Level of Concern” for shrimp meant no further testing was done.
“We don’t think there is anything we need to do to immediately ensure the safety of seafood,” Kraemer said, adding that the FDA would begin to test shrimp in the marketplace after the reopening sampling concludes. “If the levels continue to increase, we need to figure out what is going on.”
Florida officials discounted the FDA results and said their own tests showed no cause for concern.
More protective standards were issued for seafood after significant spills in Alaska, Oregon, Rhode Island, California and Maine, according to figures in a National Oceanic and Atmospheric Administration’s document titled “Managing Seafood Safety after an Oil Spill.”
After a spill, health officials set limits based on the BaPE — benzo(a)pyrene equivalent — an estimated total of the cancer-causing PAHs present in seafood.
Federal records show that after the tanker New Carissa ran aground on the Oregon coast in 1999, the state health division said that a 45 parts per billion BaPE standard in shellfish would protect the average consumer.
After a spill in California, that state chose a standard of 34 parts per billion for shellfish.
In the Gulf, the FDA set limits between 132 parts per billion (for shrimp and crab) and 143 parts per billion (for oysters), all at least three times higher than levels in Oregon and California.
The FDA said that it came up with the higher levels based on updated cancer risk data from the EPA, and data that suggest people now weigh more and live longer than when those spills occurred.
Another difference, FDA officials said, is that the agency set its levels based on a 1-in-100,000 risk of developing cancer, while California and Oregon used a 1-in-1 million risk factor.
“Basically, if more health-protective assumptions were incorporated, the allowable levels of the contaminants would go down significantly,” said Solomon, after examining the FDA’s methodology. “More samples might be within a range of concern.”
If fish had registered at even half the PAH level seen in the Florida shrimp, the fish would have been sent off for a more accurate lab analysis and the fishery would have remained closed pending those tests, according to the FDA protocol and agency officials.
But that is not what happened with the Florida shrimp.
Instead, the FDA testing was cited in an Aug. 13 letter granting Florida officials permission to open state waters for shrimping.
FDA officials said they were not concerned that the Florida shrimp samples tested about 30 times higher for PAHs than samples from neighboring Gulf states, because the shrimp remained well below the agency’s Level of Concern.
The “estimated total PAH” level found in nine Florida shrimp samples caught off Pensacola tested between 28 and 31 parts per million, according to the FDA. Shrimp in neighboring Alabama, by contrast, tested between 0.2 and 1.2 parts per million. Mississippi shrimp tested between 1.2 and 1.8 parts per million.
Kraemer said comparing samples from the different states was “not appropriate” due to factors including differences in the laboratories that conducted the testing. He also said FDA scientists do not believe the levels were actually as high as the testing suggested.
In e-mails and telephone interviews, he explained that deficiencies in the fluorescence testing method used by FDA might explain the high levels seen in Florida.
Fluorescence is a quicker and cheaper test than gas chromatography, which the FDA would use for re-testing any samples where initial results showed PAHs at half the Level of Concern for the given seafood type.
Kraemer suggested the FDA’s “estimated total PAH” in the Florida shrimp may be five to 10 times higher than the actual amount present because of “interferences” in the fluorescence tests.
As to why the Florida shrimp tested so much higher than other states, Kraemer said, “we don’t have a good explanation.”
Asked if the agency would test the shrimp further, Kraemer said, “the answer is no.”
All of the FDA’s samples were caught off Pensacola, an area that received large amounts of oil during the spill.
Officials in Florida said they had tested shrimp collected from seafood dealers in Panama City and Apalachicola and found no contamination. The officials said that they did not know where those shrimp were caught, and have not tested any shrimp from Pensacola seafood dealers.
Fish from a Pensacola-area seafood dealer tested by the state were free of contaminants, officials said.
Florida officials dismissed the FDA shrimp results because they were done with the fluorescence technique.
The NOAA paper on seafood safety after oil spills also dismisses the fluorescence method, stating, that since it “does not quantify individual aromatic compounds, the results cannot be used to assess risk to human health from consumption of contaminated seafood.”
Kraemer said the agency tested the fluorescence method side by side with gas chromatography and found the results were similar.
The agency declined to release the results of that comparison testing or the full lab reports from the reopening tests to the Press-Register without a Freedom of Information Act request.