KILLDEER (AP) - Preliminary tests of an asbestos-like mineral found in the Killdeer Mountains show it is similar to the kind linked to serious health risks. Officials say more study is needed to determine the effect on people in the area.

Joyce Ackerman, a federal Environmental Protection Agency coordinator, said the sampling of the erionite last October was not conclusive.

"We don't know if the exposure of the erionite is high enough to be a problem," Ackerman said. "Levels of erionite exposure are difficult to interpret, and we don't know what an acute threat is yet. We need to compare our numbers with what we know about asbestos."

Erionite was discovered in the Killdeer Mountains in the 1980s, and the state was considering mining it, unaware of any health risks. Gravel pits in the Killdeer Mountains serve roads and other sites in the northern two-thirds of Dunn County, officials said last fall.

State geologist Ed Murphy alerted the state Health Department to a study in Turkey that found possible links to lung cancer and mesothelioma from high exposures of erionite, and the EPA began sampling.

"The findings showed an overlap between the Dunn County erionite and other erionite found to be dangerous to those exposed to it over a long period of time," Ackerman said. "This erionite is consistent in makeup with things like iron, potassium and other chemicals."

The fibers are thin and long like asbestos, and tests indicated at least some of them are getting in the air, Ackerman said.

"This didn't happen every single time we tested. We are not sure if that was due to dampness from some rain and snow that fell the week we tested, or if there simply are not many fibers there," she said. "Fibers didn't get up into the air every single time."

The EPA, Dunn County, the city of Killdeer and state health officials want to do more study of people who have had long-term exposure to the areas where erionite has been found. Dunn County Commissioner Bob Kleeman wants to test about 20 people whose lungs would be X-rayed for signs of erionite exposure.

"First, we have to know if the person has had any other exposure to fibers which have similar effects," Ackerman said. "With erionite, there is a latency period, meaning those who are exposed don't produce cancer or lung abnormalities right away, but more like 10 to 40 years later. This would mean people probably age 50 or older would be tested if they've had a long enough latency period."

Any kind of chemical exposure depends on how long, often and much the person has been exposed, she said.

Scott Radig, director of the Health Department's division of waste management, said officials are looking at different material to surface roads.

"We are looking into ways of getting funding for the costs of putting different gravel down," Radig said.

The areas tested in October included an unused baseball diamond, where no erionite fibers were found in the air, but were present in the gravel, officials said. The diamond was raked by EPA employees during damp weather to get the gravel's dust in the air as much as possible.

The Killdeer public pool parking lot also was raked and found to have fibers in the air. Driving tests were conducted on two popular roads, and fibers were found in the air, Ackerman said.

EPA officials want to schedule a public meeting after more data is analyzed, she said.