Hot rocks: Minneapolis' "free" gravel contained asbestos.

For some residents of northeast Minneapolis in the 1970s and 1980s, the rock piles outside the Western Mineral Products plant were too good to pass up. A sign on top read "Free Crushed Rock," a boon for those in the working-class neighborhood who needed fill for their yards and driveways. The piles drew children, too, many on their way to or from the nearby schools. The rocks were fun to run around and climb on and, on cold Minnesota mornings, were often still warm to the touch.

"We all played over there," recalls Kevin Reich, who moved to the neighborhood as a sixth-grader in 1979. "It baffles the mind, but it's true." What baffles Reich, decades later, is the knowledge that those rock piles were the by-product of processing vermiculite ore mined by W.R. Grace & Company in Libby, Montana--vermiculite that is now known to contain asbestos, the fiber linked to a host of serious health problems, including asbestosis, mesothelioma and lung cancer.

The Libby mine was closed in 1990 in 1999, media coverage sparked an Environmental Protection Agency (EPA) investigation that found high levels of asbestos exposure among the town's miners and residents. Now, federal and state agencies are trying to track down the millions of tons of vermiculite shipped from Libby over the mine's 65-plus years of operation and determine who else might have been exposed. The search has led them to Kevin Reich's neighborhood and more than 200 other sites around the United States that processed Libby vermiculite.

Tracking the ore has been anything but easy, says Barbara Anderson, an environmental health scientist with the Agency for Toxic Substances and Disease Registry's (ATSDR) National Asbestos Exposure Review, which is using company documents, community complaints about air emissions, visual inspections and computer modeling to lead the national search. "This material wasn't classified as hazardous waste," Anderson says. "There are few records to document where it went."

Anderson and her colleagues have focused their initial efforts on 28 "Phase 1" sites--the processing facilities, scattered from Santa Ana, California to Beltsville, Maryland, that received about four-fifths of the vermiculite mined in Libby from 1964 through 1980. Thus far, the agency has published seven site reviews (Anderson says the remaining Phase 1 assessments will be complete by early 2005), in each case concluding that employees of the facilities, and possibly members of their households, were exposed to elevated levels of asbestos.

William Corcoran, vice president for public and regulatory affairs at W.R. Grace, the Maryland-based chemical and materials company, told E, "Any asbestos found in material shipped from Libby was in trace amounts." The company filed for Chapter 11 reorganization in 2001, citing "a sharply increasing number of asbestos claims."

At Minneapolis' Western Mineral Products plant, which operated for 51 years, raw vermiculite was "popped" or heated until the moisture inside exploded, turning the mineral into a lightweight, porous material commonly used in attic insulation, soil additives and other consumer products. The ore that didn't "pop" was often left outside: the rock piles that Kevin Reich remembers from his childhood. From there, it spread into the community, a shovel-full at a time.

"Residents would go there with their buckets and little red wagons and pickup trucks and take [the rock] back to their homes," says Tannie Eshenaur, a community health educator with the Minnesota Department of Health who has been tracking the rock the last three years. To find it, the health department and the EPA put the word out in the media, then went door-to-door to 1,800 properties, interviewing homeowners and offering free asbestos inspections. They estimated they might find 30 properties containing Libby vermiculite; instead, they found 260, some as far as 30 miles from the plant.

Dan Scoggins's duplex was one of them. At some point before he bought the property in 1992, its owner had used waste rock from the local plant to build up the gravel driveway. Scoggins unwittingly compounded the problem when, about five years ago, he gave himself the dirty chore of tidying up that driveway. For the better part of two summers, he sifted through the gravel by hand, scattering the waste over his yard.

Two years later, EPA workers, clad in protective suits and masks, were the ones laboring in Scoggins' yard, removing pockets of asbestos they had tagged with orange flags. "They took out the whole driveway and the backyard," Scoggins says. "I said 'I've lived here for years and you guys come in wearing white suits and masks?"

To date, 259 of the Minneapolis sites, including the processing plant, have been cleaned up. Officials have compiled a database of about 7,000 workers, residents and former residents who might have come in contact with Libby vermiculite. If her department gets the funding, Eshenaur says, they will comb through death certificates and the state cancer registry in an effort to link exposures to outcomes, a tricky task given that asbestos-related diseases can take decades to manifest, and can be masked by other factors like smoking.

"The exposure has essentially been stopped," Eshenaur says. "Now we need to find out the health effects."

On that front, there is plenty of cause for concern: Although their exposure levels were likely much higher than in Minneapolis, a recent ATSDR mortality review of Libby residents found that for a 20-year period, deaths from asbestosis were about 60 times higher than in the rest of the U.S.

Residents like Scoggins, though, can only wait and worry about how many asbestos fibers they might have inhaled over the years. After a long day's work on his asbestos-laced driveway, Scoggins recalls, "I'd look like a coal miner." CONTACT: ATSDR, [phone], www. atsdr.cdc.gov.