A massive area in the Gulf of Mexico totaling about 30 percent of federal water closed after BP's Deepwater Horizon disaster has been reopened for commercial and recreational fishing, the US government announced Friday.

But the news is not entirely good for America's fishermen or seafood connoisseurs.

While authorities cited tests showing seafood caught along the coasts of Florida and Alabama found no obvious oil, dispersant or chemical smell, experts say the tests did not search for toxic heavy metals which can bioaccumulate up the food chain after major disasters like an oil spill.

The area covers 6,879 square miles (17,800 square kilometers) off the coasts of Florida and Alabama, and is the ninth reopening of waters since the spill, the National Oceanic and Atmospheric Administration (NOAA) said in a statement on Friday.

At its closest point, the area is about 110 miles (177 kilometers) southeast of the BP-leased Deepwater Horizon rig that exploded in April and sank to the sea floor, hemorrhaging crude for more than 100 days.

"Each reopening is a reassuring sign that areas once impacted by oil can again support sustainable fishing activities," said NOAA administrator Jane Lubchenco.

"Tourists and consumers should know most Gulf waters are open for fishing and seafood from these waters is safe to eat."

However, in a series of exclusive reports by RAW STORY, experts outside of the government warned that Gulf seafood may not really be safe.

Tests carried out by the National Oceanic and Atmospheric Administration look for the presence of polycyclic aromatic hydrocarbons (PAHs) in the flesh of fish, but they neglect the search for toxic heavy metals such as lead, mercury and cadmium.

Those metals, which accumulate more slowly than PAHs, may pose a long term health risk to anyone who consumed them, according to Edward Trapido, the Wendell Gauthier Chair of Cancer Epidemiology at the Louisiana State University School of Public Health.

Gina Solomon, a doctor and public health expert in the department of medicine at the University of California at San Francisco, told RAW STORY the levels of heavy metals will inevitably "creep up as a result of the spill."

Solomon, a co-author on a peer-reviewed Journal of the American Medical Association (JAMA) study on Gulf seafood safety, cautioned that "we might not be seeing elevated levels [yet], but right now is the time to collect baseline information and to develop a sampling plan for monitoring into the future [...]."

And some at the NOAA worry that concentrations of the metals may have yet to peak, meaning that levels of toxic substances could be much higher three to five years from now.

"We can say that it’s safe at this point based on what we know," Trapido said. "But as a cancer epidemiologist, which is what I am, I have to maintain an air of skepticism and say, well, we don’t have any data to make a judgment on the long-term cases."

To make matters worse for Gulf fishermen, activists have claimed that many who live from catch to catch are being asked to sign legal waivers that shifts liability from BP to the fishermen for any toxic content of their product.

President Obama decided last week to lift a moratorium on new deepwater drilling projects.

The total size of the area reopened is about 29 percent of the closed area as of October 5, the NOAA said. About seven percent of federal waters in the Gulf of Mexico, or 16,481 square miles (42,685 kilometers), remain closed to fishing.

With AFP. Additional reporting by Brad Jacobson.