Fishermen who spent much of the summer mopping up oil from BP's disastrous spill got back to work as the fall shrimping season in Louisiana's coastal waters opened Monday.
Scores of shrimpers headed out at first light, and early reports indicated a plentiful and clean catch.
In Florida's Panhandle, a 23-mile stretch along Escambia County that had been closed because of the spill reopened to shrimp harvesting at 12:01 this morning. Fishing had been allowed there since July 31. Oysters, clams and mussels were not included in the closure and have always remained open to harvest. The area will remain closed to the harvest of crabs until further tests are done.
Shrimping is also open in state-controlled waters around the rest of Florida and off Mississippi, Alabama and Texas. Federal waters, which are open nearly year-round for boats to trawl for bigger shrimp, remain closed to shrimping off Louisiana, Mississippi and Alabama, though some spots could open within days, depending on the results of extensive tests.
Already, laboratory tests on seafood from the gulf have shown little hazard from oil, and a test is being developed for the chemicals used to disperse the crude, though there is no evidence they build up in seafood.
"We're taking extraordinary steps to assure a high level of confidence in the seafood," Jane Lubchenco, administrator of the National Oceanic and Atmospheric Administration, said Monday.
Don't expect the monitoring to end soon: "We're not going anywhere," Lubchenco said, renewing a pledge to keep testing even in waters declared oil-free to detect any lingering seafood concern.
Basic biology is key: Some species clear oil contamination from their bodies far more rapidly than others. Fish are the fastest, oysters and crabs the slowest, and shrimp somewhere in between.
The oil contaminants of most health concern — potential cancer-causing substances called polycyclic aromatic hydrocarbons, or PAHs — show up in other everyday foods, too, such as grilled meat. Low levels also are in seafood sold from other waters.
Here are some questions and answers about gulf seafood safety:
What are PAHs?
They're common pollutants from oil, vehicle exhaust, wood-burning fires and tobacco smoke. They can be in food grown in polluted soil and form in meat cooked at high temperatures. NOAA research found that Alaskan villagers' smoked salmon, a staple food, contained far more PAHs than shellfish tainted by the Exxon Valdez spill.
How does the government decide it's safe to reopen fishing waters?
Seafood testing begins when there's no longer visible oil in a particular area. First, inspectors smell samples for the slightest whiff of oil. Step 2 is chemical testing at the Food and Drug Administration, NOAA, or state laboratories.
To reopen seafood harvesting, the samples must test below FDA-set "levels of concern" for 12 PAHs, based on how much someone would have to eat for a potential health risk, and how much of each food fairly heavy seafood consumers tend to eat in a month. Far more than 1,200 samples have been tested with many more on the way, each sample containing multiple individual fish, shrimp, crab or oysters.
What if fishermen illegally fish in closed waters?
The government is patrolling those waters, doing dockside sampling and stepping up inspections at seafood processors.
With so much oil in the gulf, how could fish emerge untainted?
Commonly consumed finfish — like grouper, snapper and tuna — rapidly metabolize those PAHs. That has been known for years and tracked during other oil spills and is the reason fishing is being allowed first in reopened waters.
For example, the limit in fish of the PAH named benzo(a)pyrene is 35 parts per billion. In the recently reopened waters off Florida's Panhandle, levels were below 1 ppb. Similarly, last weekend the FDA labeled amounts of that chemical below the limit of detection in shrimp from Louisiana's reopened Barataria Bay.
Why haven't crabs and oysters been cleared?
They metabolize oil the slowest, plus crabs require an extra testing step that the FDA hasn't finished.
Oysters are probably the biggest absorbers of oil, as they take in droplets and dissolved oil, said Carys Mitchelmore, an aquatic toxicologist at the University of Maryland Center for Environmental Science.
Most oyster testing is just beginning, so stay tuned, although the FDA recently cleared some from Alabama that contained less than a quarter of the total PAH limit of 66 parts per million. (Note: Harvesting of Florida oysters was never halted because of oil.)
But what about that controversial dispersant — are the feds testing for it?
Not yet; they're still developing a good test.
So why do they say dispersant isn't a seafood threat?
Some dispersant chemicals are FDA-regulated ingredients in skin creams and even foods. The FDA contends the stronger cleansing ingredients under question degrade too quickly in water to accumulate in fish flesh. In experiments under way in Texas and Alabama, federal scientists are dumping dispersant into tanks full of shrimp, oysters and crabs to try to detect even minute levels.
Still, some critics say a test is needed.
"Make this as comprehensive as possible," says Susan Shaw of the Marine Environmental Research Institute in Maine. "It's trying to make sure the needle in the haystack is not there."
But the dispersant broke oil into smaller, easier-to-absorb droplets, meaning oil tests would detect seafood exposed to lots of dispersant, said Walton Dickhoff, who oversees testing at NOAA's Northwest Fisheries Science Center in Seattle.
"We believe the science is very compelling that there is not a human health concern for fish consumption with respect to dispersants," added Donald Kraemer, who oversees the FDA's gulf seafood testing.
Information from the Associated Press was used in this report.