Published: Sunday, November 28, 2010, 5:00 AM
Every Gulf fish that the government has tested since workers shut off the oil spewing from BP’s ruptured well in mid-July has shown toxins far below what is dangerous, federal authorities say.
Still, questions about seafood safety linger, highlighted by the government’s decision last week to close 4,213 square miles in the Gulf of Mexico to deepwater royal red shrimping after a trawler pulled up tar balls in its net.
But before that high-profile incident, some experts contend that the government’s standards are too lax. Others say the government’s testing ignores key toxins.
Even if a contaminated piece of fish slips through the samples tested by the Food and Drug Administration and the National Oceanic and Atmospheric Administration, the consumer who ate it probably would have nothing to worry about, according to federal scientists.
“You’d have to get the bad fish for five years,“ said Bob Dickey, director of the FDA’s Gulf Coast Seafood Laboratory on Dauphin Island.
The reason has to do with how the safety thresholds were developed and what they mean, Dickey said.
The government tests for dozens of toxic compounds found in crude oil, including those that can make a person sick immediately, and polycyclic aromatic hydrocarbons, or PAHs, which can increase the chances that a consumer will get cancer.
It sets “levels of concern“ for each compound, and the levels can be different among different seafood species.
“All of the samples have been 100-fold or even 1,000-fold below all of these levels,“ Dickey said. “Nothing ever came close to these levels.“
Not everyone is convinced, though.
“These chemicals, these are PAHs that are carcinogenic. ... These items are not in any way appropriate for anyone to eat,“ said Ed Cake, an environmental consultant from Ocean Springs. “There’s no low-dose level that’s acceptable to eat.“
William Sawyer, a Florida-based toxicologist, said the current FDA protocol allows much higher concentrations of PAHs than the government used for the Exxon Valdez spill in 1989 and other previous oil spills. He said some shrimp caught off the coast of Florida and privately tested had toxins that were at 40 percent of the FDA’s level of concern.
Applying the same analysis but using the old levels, he said, those shrimp “would be in violation and wouldn’t be on the market.“
Dickey said the FDA has revised its protocol based on better science and improved understanding of how petroleum toxins react with the body.
The thresholds governing the Gulf testing assumed seafood consumption rates in the top 10 percent as determined by a national survey. It also uses data such as average body weight and meal size.
Dickey said the thresholds come from lab experiments using animals dosed with the compounds in various amounts.
Scientists determine the amount just below that which causes cysts or other signs of cancer. Then they divide by 10 to account for the differences between animals and humans. Then they divide by 10 again to account for variation in the ways people react to compounds.
For instance, the “level of concern“ for the carcinogen benzo(k)fluoranthene is 13.2 parts per million for shrimp and crabs, 14.3 parts per million for oysters and 3.5 parts per million for fin fish.
If a person were to eat fish with the compound in concentrations above the 13.2 parts per million level, Dickey said, it probably would have not adverse health effects.
Instead, he said, that person would have to eat an average of 13 grams of shrimp at the 13.2 parts per million threshold every day for five years to increase the risk of cancer down the road. At that rate, the cancer risk from the contaminated fish would be 1 in 100,000.
Dickey provided a chart showing PAH concentrations in foods ranging from grilled meat to smoked fish to vegetables — at levels, in some cases, that exceeded the agency’s level of concern developed for the oil spill.
“PAHs have been with us for a long time, ever since man started cooking with fire,“ he said.
Bill Walton, an assistant professor at the Auburn University Shellfish Laboratory on Dauphin Island, said he and his family have eaten Gulf seafood since authorities reopened fishing waters. He said it’s important to remember that it’s impossible to eliminate all risk.
“If you don’t have the fish and have the chicken instead, do you know what’s in the chicken?“ he asked.
Walton serves on the Food Safety Task Force, a multi-state group that formed after the oil spill to advise the seafood industry on how to ensure a safe product. He said the group has considered sponsoring independent lab tests but so far has not found funding to do so.
Still, Walton said, he has faith in the government’s testing program.
“I think it’s some of the most extensive testing I’ve ever seen,“ he said. “There is no seafood on the planet that is as tested as Gulf seafood is.“
But Sawyer, the Florida toxicologist, said the government tests do not look for total petroleum hydrocarbons in the seafood. He said his tests of Gulf shrimp have shown unsafe levels of the compounds, which can cause liver or kidney damage in a matter of weeks.
Dickey said Sawyer, like several other scientists who have conducted independent tests, appears to have used a method developed for measuring oil in groundwater and soil. He said that method essentially weighs the carbon compounds in the fish tissue and considers them all petro-carbons.
The problem, Dickey said, is that fish and other animals are carbon-based. The testing method provides an inflated figure without identifying the specific carbon compounds to determine which are from the oil.
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