A new report has concluded that arsenic added to chicken feed does run off into local waterways after chicken manure is applied to fields as fertilizer, renewing efforts in Maryland to ban the feed additive.

The University of Maryland Center for Agro-Ecology commissioned the report with the hope of synthesizing the available data on the properties of Roxarsone, an additive that some chicken companies place in feed to keep the birds healthy and give the meat its pinkish color. Although some chicken companies may use other arsenicals as additives, Roxarsone, which is manufactured by Alpharma, is the main one used in Maryland's chicken industry and therefore was the report's focus.

The report concluded that the arsenic concentrations in the poultry manure are organic when the litter is first applied. But the longer the litter sits on the ground, the more rapidly it converts to the more harmful inorganic form of arsenic. Soils in Maryland and Delaware where farmers have applied poultry litter for several decades exceed the states' standards for acceptable levels of arsenic.

The report also stated that arsenic from the Roxarsone does leach into groundwater, especially in shallow aquifers, and can run off into streams during rain. When that happens, it runs off as inorganic arsenic. Fish in the sampled areas were above the state's limit for arsenic.

Inorganic arsenic is a known human carcinogen that has also been linked to vascular disease, heart disease and diabetes.

The report's purpose was to provide information and not make recommendations, but it included this opinion from a 2007 study prepared for regulators in Delaware:

"A number of papers indicate that the use of arsenic as a feed additive is not a sustainable practice since arsenic concentrations continue to accumulate over time and soil levels will eventually increase to concentrations above these background remediation standards."

The Center for Agro-Ecology produced the report for the Environmental Matters Committee in the Maryland House of Delegates, which asked for it last year. Daniel J. Fisher, Lance T. Yonkos and Kenneth Staver conducted the 43-page analysis.

The committee was considering a bill during the 2011 session to ban arsenic in chicken feed, but wanted a better picture of how it interacted with the Eastern Shore's waterways. Prince George's County Sen. Paul Pinsky introduced the Senate's bill, while Montgomery County Del. Tom Hucker sponsored the House's companion bill. Testimony on the affects of Roxarsone was occasionally confusing, and little was known about how much of it was in the chicken manure that is applied to fields and how it interacted with soils once it got there.

"They had people reporting on the human health impacts, but they didn't have much information on the ecosystem health impacts, so they asked us to address those issues," said Russ Brinsfield, the center's executive director.

Barely two weeks into the session, Pinsky and Hucker re-introduced a bill that prohibits a person from using, selling or distributing chicken feed with Roxarsone or any other additive containing arsenic.

Del. Maggie McIntosh, chair of the committee, said she would co-sponsor the legislation after reading the report's findings.

"We had confusing and opposing testimony on things like inorganic versus organic," McIntosh said. "Now that the scientific study has been completed, it's very clear."

Among those leading the charge to ban the substance in chicken feed was Maryland Attorney General Douglas Gansler. Several environmental groups, including Environment Maryland and Food and Water Watch, as well as the Chesapeake Bay Foundation and many Riverkeeper groups, pushed for the legislation to remove Roxarsone from chicken feed last year. They were expected to do so again. Food and Water Watch has been offering movie screenings, letter-writing campaigns and other events across the state to educate legislators and gather grass roots support.

"As you can imagine, for anyone who is just learning that they can be feeding a common poison to their families, it can be pretty shocking," said Jorge Aguilar, Food and Water Watch's Southern Region director. "It leads to questions about food safety and why this arsenic was used in the first place."

Roxarsone has been approved by the FDA since 1944 to use in chicken feed. But the European Union stopped allowing it in 1999 because of health concerns. In 2007, Perdue, the nation's third largest chicken producer, stopped using it. That same year, McDonald's, one of the largest purchasers of chicken meat, asked its suppliers to stop using it in their feed. Last year, the Food and Drug Administration announced that Alpharma, a Pfizer subsidiary, was voluntarily suspending its Roxarsone sales. That decision came after an FDA study that showed possible harmful affects.

But the voluntary recall does not stop the chicken companies who already have the drug from using it, as the feed makers add the drug themselves. Alpharma also could change its policy at any time and resume selling the drug, or other companies could enter the market.

"It's a public health thing and a common sense thing," said Environment Maryland's Tommy Landers of the proposed ban.

Yet it was a hard sell last year. Some rural legislators objected to the ban. Sen. E.J. Pipkin called the move another nudge in what he considers an age-old push to drive poultry producers out of Maryland. Some conservatives didn't like adding more regulation. And the powerful pharmaceutical industry, whose lobbyists had access to powerful committee leaders, fought the bill. Environmental groups, in contrast, said they did not enjoy such access. One advocate, Choptank Riverkeeper Drew Koslow, said he and fellow environmentalists didn't have access to an influential senator until she had already made up her mind.

But McIntosh said that, armed with the information that arsenic does leak into the waterways, she questions who would oppose the legislation now.

"I can't see what the opposition would be, except they might say, 'well, look, this is a precedent,'" McIntosh said. "But we have banned other harmful substances, so it is not precedent-setting."

Fisher, the aquatic environmental toxicologist who led the review, was hesitant to give his recommendation on a ban in a recent interview with the Bay Journal. But when asked if he would eat from a chicken that was fed Roxasarone, he said, "I now buy chicken from Perdue when I eat it, or I try to if it's available."