Dumping radioactive waste into the world's seas began in 1946 with a scientific argument whose foundation was the vastness of the oceans."It was no stretch (for officials) to assume that, like fish stocks, the ocean would rejuvenate itself through dilution, and that it had a definable annual capacity to do so for radioactive waste," Jacob Darwin Hamblin wrote in Poison in the Well, a history of dumping during the Cold War.What was true in the 1940s is true today — some mainstream scientists argue the oceans can absorb and disperse radiation so that it is harmless.But few argue that the ocean is a good place for radioactive waste. Some scientists say radioactivity from dumps can make its way into the marine food chain. The barrels of radioactive waste dumped by the U.S.S. Calhoun County during the Cold War had a lifespan of 30 years, and scientists believe they have leached radioactivity into sea sediment.It didn't help that the Navy shot "floaters" – barrels that sometimes would sink only after taking rifle shots or, at least once, a strafing by military aircraft. Scientists also note that many barrels imploded from ocean pressure as they fell to the sea floor.Navy spokesman Kenneth Hess pointed to a 1981 General Accounting Office study that said the environmental danger of dumping was overblown."Testimony at numerous congressional hearings, including statements by EPA, the Department of Energy, and the Nuclear Regulatory Commission, have supported . . . that past ocean dumping of radiological waste does not pose a serious risk to human health or the environment," Hess said.Even so, scientists say the issue of the impact of radioactive dumps on both the environment and human health requires more study. That is made more difficult because the Navy did not keep detailed records about the materials dumped."The ocean's solution to pollution is dilution," Ken Buesseler, a Woods Hole Oceanographic Institution marine chemist, said in 2011 when discussing radiation from Japan's Fukushima reactor.Buesseler is no advocate for ocean dumping, but he said the oceans already contain radioactivity, including from nuclear tests in the Cold War. In an incident such as Fukushima, radiation spreads from a source and is diluted as it moves away."Dilution does happen," Buesseler told the Tampa Bay Times. "We can still be concerned about these unknown sources of radioactive wastes. But levels will decrease the farther you go from the source. … As that radioactivity makes its way into the ocean, concentrations will become much lower offshore, so that we are no longer as concerned about human exposure in the ocean and external doses."But some scientists aren't convinced."The reality is, if you dump radioactive waste in concentrated areas, most of it will not be evenly distributed throughout the ocean," said Thomas Suchanek, a research ecologist who studied Navy dumps off San Francisco. "Most of it will remain in that location and will contaminate organisms in that local area."The nation has come a long way from the U.S. government's careless attitude toward atomic waste during the Cold War when a government handbook on ocean dumping said, "It seems very reasonable to assume that producers or users of radioactive isotopes located on or near the coasts, or on inland waterways, may find it simpler to dispose of virtually all wastes at sea."The handbook warned of the down side."Unfavorable situations might arise if a package of radioactive material were found on the shore or recovered in a fisherman's net or by a trawler or dragger," it said. "Unsound rumors that marine food products contain sufficient quantities of radioisotopes to be detrimental to health should be countered rapidly and effectively."