WASHINGTON, May 19 (UPI) -- The danger to the U.S. food supply posed by last month's Gulf oil spill is greater than previously estimated, government officials and scientists say.

Lisa Suatoni of the Natural Resources Defense Council says chemicals being used to disperse the oil could have a lasting impact on the ocean's food chain, USA Today reported Wednesday.

Animals that don't die from exposure to the chemicals pose a hazard, Suatoni says.

"Anything that eats them could get a concentrated dose of that (chemical)," she says, adding that testing of seafood may be necessary for a very long time.

Testing includes taking daily laboratory samples and using people who can smell the presence of oil in seafood.

Tuesday the National Oceanic and Atmospheric Administration doubled the area in the Gulf where commercial and recreational fishing is temporarily off-limits.

Gulf products account for about 5 percent of the seafood consumed in the United States