ELLWOOD CITY -- Growing up in the west end of town during the 1960s, Keith Foley and dozens of other kids spent every summer day at a playground near a plant owned by W.R. Grace and Co.

The playground had a baseball field and a patch of grass the kids used for football, along with the usual swing sets and monkey bars. But the playground also had a component unique to its location, silver-colored rocks and gravel, which were byproducts of a material produced at the Grace plant.

"We all joked about it growing up," said Mr. Foley, 50, who now lives in Wayne, in another part of Lawrence County. "We went home every day dusty and dirty and, when it was raining, we went home looking like the Tin Man from "The Wizard of Oz," covered with silver muck."

In September, federal officials distributed a health alert to people in Ellwood City about the potential harm from asbestos exposure from the waste rocks discarded by the Grace plant. The Agency for Toxic Substances and Disease Registry, a sister agency of the Centers for Disease Control and Prevention and an investigative arm of the Department of Health and Human Services, was unaware of the existence of the playground until it received a telephone call from Mr. Foley.

As a result, agency officials set up a public meeting this week to learn from people firsthand about their exposure to the waste rock at the playground and whether they had taken any of the rock home for use in driveways or yards. About 50 people attended the meeting in the Ellwood City municipal building.

Many were upset when they learned about the possible asbestos exposure in the community, whether they were youngsters on the playground, workers and their families from the Grace plant or those who lived near the plant on Factory Street. Generally, workers have the highest risk of health problems from asbestos exposure.

Michael Lynn Williams, known in the community as Mikey, lived for 33 years across the street from the plant site. Ms. Williams, 52, was in the playground every day with Mr. Foley and other kids, playing games, such as king of the hill, on the piles of waste rock, and she remembers the rock being covered over every spring with dirt and a new layer of grass.

Ms. Williams has had a heart attack and carries a portable oxygen tank she uses because of respiratory problems.

"I'm only 52 and I look like I'm 70 and I feel like I'm 99," Ms. Williams said.

The Ellwood City plant and another in New Castle manufactured Zonolite, a material used in products that included insulation, pesticides and fertilizer. Zonolite is made from an ore called vermiculite, which was mined in Libby, Mont., and which contains tremolite asbestos, a particularly toxic type of asbestos. Vermiculite was mined in Libby for more than 65 years until Grace closed the mine in 1990.

The Ellwood City plant operated from 1954 to 1969 and the New Castle plant from 1969 to 1992. Federal officials believe the work force moved with the plant between the two communities.

Asbestos exposure can cause a variety of respiratory illnesses which include asbestosis, or scarring of the lungs, and mesothelioma, a particularly severe and fast-spreading form of lung cancer.

The illnesses can remain undetected for years, even decades, said Dr. Vikas Kapil, senior medical officer of occupational and environmental medicine with the Agency for Toxic Substances and Disease Registry based in Atlanta. Dr. Kapil was in Pittsburgh this week for a conference.

There have been no studies done on the effect of asbestos exposure to people who lived near a plant or who would have had exposure from a play area, such as the Ellwood City playground, Dr. Kapil said. The first such study is to be started soon by the University of Minnesota and will examine residents of a Minneapolis neighborhood that was home to a Zonolite plant, he said.

But there have been studies of asbestos contamination in workers, most extensively in Libby. One study examined mortality in Libby and was released more than five years ago by the Agency for Toxic Substances and Disease Registry and the Montana Department of Public Health and Human Services.

The federal study revealed an increase in Libby of 20 percent to 40 percent in respiratory deaths from 1979 to 1998, compared with mortality data in Montana and the rest of the country. In addition, Libby residents had mortality rates from asbestosis 40 to 80 times higher than expected and 1.2 to 1.3 times higher from lung cancer compared with the rest of Montana and the United States.

W.R. Grace and seven of its current and former executives were indicted last year on federal criminal counts of violating the Clean Air Act and other charges stemming from an alleged conspiracy to conceal the hazards of asbestos exposure to mine workers and people in Libby. The trial is set for the fall.

Grace, based in Columbia, Md., also faces thousands of lawsuits from people nationwide who blame deaths and illnesses on exposure to asbestos from the company's products or businesses.

Facing the raft of lawsuits, Grace in 2001 filed for protection from its creditors under Chapter 11 of the bankruptcy code. The case is being overseen by U.S. Bankruptcy Judge Judith Fitzgerald in Pittsburgh, who has been hearing cases from Wilmington, Del., because of a backlog.

The former Zonolite plants in Ellwood City and New Castle are among 28 locations nationwide that are being evaluated by the Agency for Toxic Substances and Disease Registry as part of an overall examination of the extent and manner of asbestos exposure and to determine whether the exposure constitutes a public health hazard.

The plants are among more than 200 across the country that processed vermiculite from Libby. The 28 plants that are part of the federal evaluation were chosen because an examination by the U.S. Department of Environmental Protection found contamination at the site or because the facility processed at least 100,000 tons of vermiculite.

The two Lawrence County facilities produced Zonolite by heating vermiculite in furnaces until it expanded in a process similar to popping corn. The resulting product, sold under the brand name Zonolite after Zonolite Mountain in Libby, where it was mined, was most commonly used in insulation. The insulation might be in as many as 35 million homes, according to previously published accounts.

The popping process, known as exfoliation, posed an extra danger to workers because more asbestos was released into the air than through other production methods.

Fred Hogue, 70, worked as a teenager in the Ellwood City plant and remembers the waste rocks being dumped in the playground. Mr. Hogue loaded vermiculite in one of three furnaces in the plant. He has been diagnosed with asbestosis.

"At that time, they did nothing about it," Mr. Hogue said. "You weren't even issued a respiratory mask."

The playground in Ellwood City is gone, buried beneath a paved parking lot for the borough's Moose lodge. Federal health officials want to examine the site further by talking to contractors and others who were involved in the removal of the playground and construction of the Moose.

The next step in the evaluation process will be to prepare a report of each of the 28 Zonolite sites and determine whether further review is needed, said Barbara Anderson, an environmental health scientist with the Agency for Toxic Substances and Disease Registry who was in Ellwood City last week. Then statistics could be collected on asbestos-related diseases among residents, something that was done in detail in Libby, she said.

But Ms. Anderson said her agency did not have any regulatory power and would only provide recommendations for action by other federal agencies.

While federal officials have heard from people familiar with the Ellwood City plant, they have yet to hear from anyone who worked at the New Castle facility.

For information about asbestos risks from the plants in Ellwood City or New Castle, contact the Agency for Toxic Substances and Disease Registry by calling toll-free 1-888-422-8737. Additional information about the Zonolite plants is available at the agency's Web site, www.atsdr.cdc.gov.