MIAMI — The Gulf of Mexico oil spill still poses threats to human health and seafood safety, according to a study published Monday by the peer-reviewed Journal of the American Medical Association.
The report came two days after President Barack Obama and members of his family swam in the gulf at Panama City Beach and mere hours after this year's commercial shrimping season officially kicked off along the Louisiana coast.
Federal officials disputed the new report and said ongoing testing is aggressive and sufficient to protect public health.
In the short term, study co-author Gina Solomon voiced greatest concern for shrimp, oysters, crabs and other invertebrates she says have difficulty clearing their systems of dangerous polycyclic aromatic hydrocarbons, or PAHs, similar to those found in cigarette smoke and soot. Solomon is a medical doctor and public health expert in the department of medicine at the University of California at San Francisco.
In the longer term, she expressed worries about big finfish such as tuna, swordfish and mackerel, saying levels of mercury from the oil might slowly increase over time by being consumed by fish lower in the food chain and becoming concentrated in the larger fish.
Some of the fish had relatively high levels of mercury even before the oil spill, she said.
"It's like iron filings to a magnet," she said. "Several years from now the concentration will go up in fish at the top of the food chain — tuna, mackerel, swordfish."
Solomon said she based her new report on studies from past oil spills, including the Exxon Valdez event off Alaska in 1989, plus her own monitoring of current gulf data from the National Oceanographic and Atmospheric Administration, the Environmental Protection Agency and the Food and Drug Administration.
FDA officials disagreed with Solomon's fears about PAHs.
"We don't agree that's currently a problem," said Vicki Seyfert-Margolis from the office of the chief scientist of the FDA. Seyfert-Margolis said federal officials have a "mussel watch" program to test for such contamination in all shellfish, and so far no problems have been found.
As each gulf area is reopened for finfish harvest, she said, officials are testing shellfish separately, approving various species only as studies are completed.
Crabs and oysters take longer to test and clear because people eat the entire animal, including the liver, where toxins can accumulate, she said.
Seyfert-Margolis agreed that testing must continue for finfish to make sure toxins don't build up in the future. Such testing will begin if similar early problems come up in the mussel-watch program, she said.
"We have the ability to test it in finfish. We can study it as long as necessary," she said.
Concerning the human effects of the oil spill, Solomon says: "The good news is that the levels of benzene, the most dangerous chemical from oil, have been quite low. It's not likely there's a long-term risk from inhaled vapors for coastal residents."
She went on: "For oil workers it might be a different story. The people out there deploying boom and burning the oil have been exposed to higher levels of vapor."
Solomon said that on Tuesday the National Institutes of Health will announce a long-term health study of 20,000 gulf workers and residents.