The Plum Island Animal Disease Center is seen on Plum Island off the east coast of New York’s Long Island in this Feb. 16, 2004, file photo. Despite environmentalists’ concerns about the legacy of studies on dangerous animal diseases and top-secret Army germ warfare research, authorities have removed vast amounts of waste and contaminants from Plum Island. The Department of Homeland Security is preparing to sell the 840-acre pork chop-shaped island off northeastern Long Island and build a new laboratory to study dangerous animal diseases in Kansas.

Garden City, N.Y. ? Government documents obtained by The Associated Press show extensive efforts since 2000 to remove vast amounts of waste and contaminants from Plum Island, site of top-secret Army germ warfare research and decades of studies of dangerous animal diseases.

Yet some environmentalists remain concerned about the secrecy surrounding the 840-acre, pork chop-shaped island off northeastern Long Island — and they’re dubious of any claims that pollution has been remedied.

“We are highly concerned that when the government acts alone they may not be doing the best job,” said Adrienne Esposito, executive director of the Citizens Campaign for the Environment. “Every government cleanup needs the public’s involvement and independent oversight to ensure its validity.”

The Department of Homeland Security is preparing to sell the island 100 miles east of Manhattan and build a new high-security laboratory in Kansas to study animal diseases.

The lab is to be called the National Bio and Agro-Defense Facility, or NBAF.

Documents, some obtained by the AP under the Freedom of Information Law, reveal that hundreds of tons of medical waste, contaminated soil and other refuse have been shipped off the island for disposal. Other island sites have been cleaned in compliance with federal regulations, the reports indicate.

Also, the U.S. Army Corps of Engineers determined in 2006 that no munitions or ordnance remain from the Army base on Plum Island that once housed as many as 4,000 troops from the Spanish-American War through World War II. And as late as 2007, New York government inspection reports said there is no environmental threat on the island.

Plum Island’s remote location, restricted public access, and best-selling books have all helped fuel a mystique about what goes on there. It wasn’t until the early 1990s that tours of the facility were given to the news media — about the time the government declassified files revealing secret germ warfare research there in the 1950s. The last media tour was in 2004.

Before the island, its ferry dock and mainland offices can be sold, the General Services Administration, which manages federal properties, is studying the environmental impact of the research activities. A draft is expected by summer’s end and public hearings will follow.

“There has been some EPA investigation and remediation,” said Bob DeLuca, president of the Group for the East End, which focuses on environmental issues. What has not been assessed — and what we have asked for is — what is the legacy of contamination?”

The Preserve Plum Island Coalition, a new consortium of more than two dozen environmental groups, opposes the sale. Spokesman John Turner said the island should not be developed because it is home to a number of endangered bird species and other wildlife. “We want it (the sale) to be reversed,” Turner said. “We think there are very significant ecological, natural and cultural resources on the island.”

Democratic U.S. Rep. Timothy Bishop questions the wisdom of moving the lab to Kansas. He estimates the sale could fetch $50 to $80 million but says building the new facility would cost 10 times that much. DHS, which took over Plum Island operations in 2003, considered several locations, including Plum Island, before choosing a site at Kansas State University in Manhattan, Kan.

But questions remain; the Senate last year ordered DHS to study whether operating a lab and studying pathogens in the “beef belt” could imperil America’s livestock industry.

DHS has determined that an accidental release of foot-and-mouth disease would have a $4.2 billion impact on the economy, regardless of the lab’s location.

A 2006 Army report noted how the Chemical Warfare Service researched pathogens in the 1950s that could be used for “both defensive and offensive purposes” on a variety of animals. The island was used because of federal laws banning germ warfare research on the U.S. mainland.

Army records also indicate at least hog cholera virus and Newcastle disease, a virus of poultry and other birds, were “field tested” on Plum Island, but the report noted it was never clearly established “how many other viruses the CWS may have used in their research.”