Some evidence suggests the weapons might have leaked - or will leak in the future - as the ordnance corroded from exposure to salt water. Steel containers and shell casings corrode at different rates, depending on the depth and temperature of the water.
When released, nerve gas lasts about six weeks in the ocean, killing every organism that it touches. Mustard gas forms a concentrated gel that survives at least five years in salt water, rolling around on the ocean floor.
"It just seems so unconscionable to me for the military to just wash their hands of it and not tell people where they are until now," said John Hocevar, an ocean specialist for Greenpeace, a worldwide environmental organization. "It seems like it's a threat that won't just go away."
Greenpeace - known to stage dramatic demonstrations to garner publicity for its causes - is considering an expedition to one of the dump zones identified with nautical coordinates by the Army, Hocevar said.
The idea is to dive with cameras and environmental testing equipment to see whether the weapons are leaking or whether there's evidence that they've leaked. A Geiger counter would be brought along to ascertain the danger from about 500 tons of Army-dumped radioactive waste at the sites - important because the Army doesn't know how radioactive it might be, Hocevar said.
"They need to tell us where all of it is," said Michael Town, director of the Sierra Club of Virginia. "They need to be transparent. They need to tell us what the impact is to the environment and our coasts. The public needs to be kept abreast about what they're finding. The public has been in the dark too long."
The Daily Press' investigation was published in news media outlets worldwide and drew an international response.
New Zealand's diplomatic query was prompted by revelations from U.S. National Archives records that the United States kept a chemical-weapon stockpile in that Pacific Ocean country at the close of World War II.
Newly released Army records show that the United States dumped its overseas stockpiles, as well as captured enemy stockpiles, off whatever country the weapons were in when the war ended. Those included Australia, India, Japan, Italy, France and Denmark.
The Varda Group is an international environmental organization. It's called for an international law to require all countries that dumped chemical weapons into the world's oceans to publicize their locations, monitor the sites to see whether they're leaking, and clean them up or contain them, if possible.
Such a law "should develop and disseminate best practice for waste retrieval, capping or any other appropriate measure on a case-by-case basis to avoid passing the buck to future generations," Varda Group spokesman Rémi Parmentier said.
An international treaty signed in 1975 prohibits the ocean dumping of chemical weapons but doesn't cover dump zones created before the ban. The Army halted ocean dumping in 1970.
The Daily Press investigation was also discussed at a recent symposium on chemical weapons in Moscow. The conference was attended by minister- and ambassador-level representatives from around the world. It was conducted to talk about Russia's delays in adhering to a separate international treaty that requires disposal of its chemical-weapon stockpile by 2011, as is being done by the United States.
During breaks in the conference, the newspaper's articles were read and translated for those who couldn't read English, Craig Williams said. He was there for the Chemical Weapons Working Group, a grass-roots organization in Kentucky that's active in chemical-weapon disposal issues.
No one was especially surprised to learn that the United States extensively dumped chemical weapons into the ocean, Williams said. But many attendees were astonished to learn that the U.S. Army didn't know where it tossed all the weapons, he said.
"It was quite a topic of conversation," Williams said. "The general response was ... 'You're telling me they took this out and dumped it, and they don't know where it all is?' Well, yes."