Fifteen years ago, when Bill Stephens opened his automotive repair shop in Medford, he paid for a slew of environmental tests to ensure that the property was safe. Trace amounts of a toxic liquid were detected in ground water below the shop, but he was assured there was no problem, and state officials cleared him to open for business.

Then two years ago he received a letter from the state Department of Environmental Protection, telling him the agency was auditing his property for potentially dangerous levels of the chemicals known as PCEs, or perchloroethylene. New studies had found that the chemicals, often used by dry cleaners, could cause cancer in much smaller amounts than previously thought, especially when they emit vapor.


“It was incredibly alarming,’’ said Stephens, 45, who worried about the health consequences, as well as the viability of his business.

The updated science has sparked audits of about 600 properties in Massachusetts, resulting in owners paying millions of dollars to comply with new requirements for monitoring soil and water and protecting people from the hazardous vapors.

Environmentalists applaud the state’s increased scrutiny and tougher standards to protect the public.

But homeowners, companies, and others have questioned the state’s actions and urged officials to provide clearer guidelines about how to meet the new limit, which is a tiny fraction of the old threshold. And they worry that future studies could spark new audits, requiring them to spend even more money to keep up with shifting standards.

“This uncertainty about what levels are safe and what response [is] . . . sufficient feeds into a whole lot of anxiety and fear for people, which seems unfortunate and unfair,’’ said Lisa Goodheart, an environmental lawyer who serves as president of the Boston Bar Association and represents several properties that have been audited. She said her clients are concerned about “extended uncertainty and confusion’’ caused by the new requirements and their effect on how they use their property.


Kenneth Kimmell, commissioner of the Department of Environmental Protection, said he has heard the concerns and plans to revise a draft policy that outlines what owners of contaminated properties must do, probably before the end of the year.

“My review of this has shown this is a real problem, and DEP is doing the right thing by focusing on it,’’ he said of the threat from the chemical vapors.

“On the other hand, the people trying to take contaminated properties and put them to productive use are our partners, not our adversaries,’’ Kimmell said. “It’s very important to make sure there are clear, predictable standards.’’

David Begelfer - chief executive of NAIOP Massachusetts, an advocacy group for the state’s commercial real estate industry - sent Kimmel a 52-page letter urging the commissioner to make it easier for property owners to get the state’s seal of approval and limit their liability.

He said he hoped the final policy does not require properties to submit to continuous monitoring or unnecessary deed restrictions, after beging deemed safe.

“It’s a serious problem,’’ he said. “If there’s no closure, it means financing is at risk, tenancy is at risk, and you risk bankruptcy because there’s an impression of an ongoing problem, after, in some cases, millions of dollars have been spent.’’

Some environmental advocates, however, argue that the state should do everything it can to ensure that the properties are safe, including monitoring them indefinitely, if necessary.


“If new science indicates that levels previously thought to be safe create potential health risks, DEP needs to increase monitoring to identify and mitigate impacts,’’ said James McCaffrey, director of the Massachusetts Sierra Club. “The primary goal here is protecting public health.’’

Wendy Heiger-Bernays, an associate professor of environmental health at Boston University School of Public Health, compared the state’s actions to how health officials had to ratchet up their response the more they learned about the harmful effects of cigarette smoke.

“We used to think the effects of smoking were only on the smoker, and the effects were typically thought only to be cancer,’’ she said. “Now we know one smoker in a family can cause respiratory illness in other relatives and that smoke in a room is sufficient to cause illness to someone else.’’

Before the new studies found that minuscule levels of PCEs could cause serious health problems, little was understood about the effects of the chemicals in vapor form, Heiger-Bernays said.

The previous studies assumed the chemicals degraded over time, but new findings in 2006 showed that does not happen.

The new research led the state to set the maximum level of the chemicals in ground water at 50 parts per billion, down from 3,000.

“Because we have better methods for measuring their presence and what they do to mammals, we can expect the acceptable levels are going to decrease,’’ Heiger-Bernays said. “People are breathing this, and if nothing is done, there is certainly a possibility of them developing cancer.’’


Among the sites the state audited was Lilla G. Frederick Pilot Middle School in Dorchester, which opened in 2002 on the lot of an old supermarket that had a dry cleaner. Teachers and parents of the 500 students aired concerns when the news got out in 2007.

City officials thought they had dealt with the issue before the 150,000-square-foot school opened and were surprised to learn they had to spend thousands of dollars to upgrade the ventilation system and filter the air.

“This adds to our operating costs and is something we won’t get rid of unless we dig up the building and put it on stilts,’’ said Jeff Lane, an environmental specialist for Boston public schools, adding that the state now requires annual tests twice a year. “But we believe we have a good, viable solution.’’

For Stephens, the audit led to a nightmare.

He said he has paid more than $250,000 to find a solution to a problem that came from a now-closed dry cleaner across a parking lot from his shop.

“We would have never bought the property, had we known what was here,’’ he said.

Over the past two years, he has installed air scrubbers, sealant in the walls, boring holes in his floor, and a high-tech air filtration system. But the contaminants remain in the groundwater.


“At this point, I’m virtually bankrupt, and my business is in limbo,’’ he said. “I can’t sell, can’t refinance, and I can’t rent.

“And we still don’t know what the effects are on us after working here for all these years.’’

David Abel can be reached at dabel@globe.com. Follow him on Twitter @davabel.