Critics said the report shows the Bush administration sought to minimize the benefits of reducing mercury pollution in order to justify not requiring power plant owners to buy the most effective technology for lowering mercury emissions.
"EPA has a track record of withholding information that doesn't support their agenda, and this is the latest example," said Felice Stadler, a National Wildlife Federation policy specialist.
A separate EPA-commissioned study released in February by the Harvard Center for Risk Analysis estimated there could be $5 billion a year in public health benefits from a 62.5 percent cut in the mercury released by power plants. That study too was excluded from consideration in the new rule EPA released in March.
The report on Southeast benefits, a copy of which was obtained by The Associated Press, looked at reducing mercury concentrations in marine fish and shellfish.
It did not estimate the cost of achieving this reduction but said reducing national mercury emissions by 30 percent to 100 percent would produce Southeast benefits of between $600 million to more than $2 billion.
This report also found a mercury "hot spot" — deposits of the toxic metal stretching across 50,000 square miles in the South Atlantic, from North Carolina to South Florida.
The existence of such a large mercury concentration raises questions about public assertions by EPA officials that their new rule would prevent such hot spots.
Announcing the new regulations in March, EPA's air quality chief, Jeffrey Holmstead, said, "We don't think there will be any hot spots. We're quite confident of that."