Federal occupational safety officials are investigating complaints that prison labor crews and staff are exposed to toxic contaminants in a recycling plant at a U.S. penitentiary near Modesto.

A safety manager at Atwater federal prison alleged in a January complaint that 120 convicts, along with some supervisory staff and correctional officers, are exposed to potentially dangerous dust containing lead, cadmium and barium from a recycling operation on the prison grounds.

Atwater is a high-security men's facility south of Modesto in the San Joaquin Valley.

Convicts use hammers to smash open computers, retrieving internal components that are then reused or sold, said Leroy Smith, the prison safety official who filed the complaint with the U.S. Occupational Safety and Health Administration in San Francisco.

Dust with hazardous metals found in computers drifts throughout the factory and warehouse, posing a risk to anyone who comes into contact with it or breathes it, Smith said. The EPA and OSHA have found that long-term exposure to the hazardous metals may cause kidney damage and increase the risk of lung and prostate cancer.

Smith and another prison safety official were so concerned after tests on three inmates showed elevated levels of barium that they recommended the plant be shut down temporarily to fix the problems, he said.

So far, however, the prison has agreed only to superficial fixes, playing down the safety risks in its response to OSHA, Smith said. For that reason, he has decided to go public with his concerns.

"They stopped taking my advice and took away my authority," said Smith, who went out on disability leave in October and is being treated for anxiety and depression related to his complaint. "They tried to make it personal by calling into question my job performance. But I don't see this as personal. I see it as my job. It's called protecting the safety of the staff and inmates to the best of my ability."

Atwater's warden, Paul M. Schultz, and other prison officials did not return repeated phone calls last week.

Frank Strasheim, federal OSHA's regional administrator in San Francisco, confirmed the probe into Atwater's computer recycling program. The complaint was lodged with OSHA Jan. 24, and prison officials filed a detailed response Feb. 11. Investigators are reviewing that reply.

No on-site inspection of the prison has been conducted, but Strasheim did not rule out that possibility.

"That is part of the process if we are not satisfied with the results," he said. "What we are after [when problems persist] is corrective action."

Since 1998, Unicor, a division of the federal government that uses prison crews in business ventures, has operated an expanding number of computer recycling plants at prisons nationwide, hoping to become a major player in the emerging business. Inmates can earn up to $1 an hour breaking apart the computers and sorting the parts.

But the program has come under fire in recent years by union and environmental groups that charge prisoners are using crude methods to scavenge parts. Inmates wear jumpsuits and work gloves as they smash the machines apart, but do not have goggles, Smith said. Until Tuesday, they ate their lunches within 25 feet of the factory line, exposing their meals to the contaminants, he said.

By contrast, private recycling firms place computer terminals inside a canister to capture any dust and spills when they are smashed open, Smith said. Workers are also protected by goggles, protective suits, gloves and sophisticated ventilation systems, he said.

Jeff Ruch, executive director of Public Employees for Environmental Responsibility, said he is alarmed by the conditions described at Atwater. But the federal prison system has refused to admit there is a problem, much less implement costly safeguards at its Unicor programs in Ohio, New Jersey, Pennsylvania, Florida, Texas, Arizona and California, Ruch said.

"The federal Bureau of Prisons has spent the past three years doing its best to mask the problem," he said. "They have a powerful economic incentive to keep the problem under wraps."

Smith said he became concerned in September when blood tests from three inmates working in the plant revealed elevated levels of barium. Wipe tests on various surfaces in the plant detected the presence of lead, cadmium and barium, though at levels considered acceptable for human health, he said.

Still, Smith and another safety official at the prison believed the problem was serious enough to recommend the operation be shut down while they conducted more testing of workers' blood.

Their recommendations went unheeded, Smith said. His superiors put so much pressure on him to back off, telling him that his actions were "inflammatory and hostile," that he went out on stress leave in October, he said.

In January, he filed his complaint with OSHA. Atwater's written response to the complaint, a copy of which Smith obtained, downplayed the results of blood tests and left out critical recommendations made by Smith and another safety officer, according to Smith and the documents.

Recommendations to remove air hoses that blow the dust around the factory, to provide better protective gear and to perform random testing of inmates' blood for the presence of contaminants were left out, he said. Smith believes that was done out of fear that it would be too costly to implement. "They don't want to admit there are continuing issues," he said. "It just boils down to money."

Smith said inmates are aware of the problem but don't speak up because they know they will lose their jobs if they do. The recycling plant positions are the best paid in the prison system, he said. Even if the convicts complain, few people listen to them, he said. "I'm not a sympathizer by any means," he said. "But they are humans."

Times staff writer Fred Alvarez contributed to this report.