Researchers have uncovered evidence that a type of mineral found widely throughout the western United States may be linked to a rare form of lung cancer previously believed to be caused only by human exposure to asbestos.
British and Turkish medical experts found recently that at least 10 residents of two small villages in central Turkey had developed mesothelioma, a cancer of the lung lining, which until now had been associated only with asbestos.
A member of the British medical team told a scientific gathering in New York on Friday that the Turkish villagers apparently developed the disease after breathing dust that contained a member of a mineral family known as zeolites.
U.S. medical and geologic experts, who took part in the New York Academy of Sciences symposium last week where the findings were revealed by British lung disease specialist Dr. Peter Elmes, said yesterday that the Turkish report was still "very preliminary." But they urged a rapid investigation of potential harmful effects from zeolites in the United States.
The mineral family is found widely in soft rock formations from the Caadian border to southern Arizona in the West. About 40 types of the mineral occur naturally and scientists have synthesized 100 other varieties in what is considered a rapidly growing field of use for the mineral.
Thus far, there has been little scientific investigation into potentially hazardous properties of the fibrous mineral, scientists said. It is still unclear what, if any, potential damage it may have caused to persons living near natural formations of zeolites in the West, they said. But one expert said yesterday the latest findings should constitute a "warning flag" to spur government research in the area.
D.E.W. Vaughan, a research manager at the W.R. Grace Co. Washington Research Center in Columbia, Md., said that one form of zeolite with a chemical structure close to asbestos is being tested by the Environmental Protection Agency to clean up municipal sewage waste.
Vaughan, an expert in the mineral, said a type of zeolite called erionite, which has needle-like fibers, may possibly cause the same scarring of lung tissue that asbestos does. The scarring leads to mesothelioma, a usually fatal cancer.
Zeolites with other chemical structures are also widely used in refineries, Vaughan said, to aid in the distillation, or "cracking," of crude oil into gasoline.
Dr. Irving Selikoff, of the Mt. Sinai Medical Center in New York, said yesterday his researchers had also tentatively linked zeolites with lung damage similar to that caused by asbestos. Sellikoff said he has recently treated two patients - one a refinery woorker - whose lungs were damaged after exposure to zeolites.
"This is simply first observation but it does give us some direction since we have two separate sources," Selikoff said. He said the findings appear to support some earlier research done at the National Cancer Institute showing that all fibrous minerals with asbestos-like composition should be considered potentially dangerous.
Another expert in the mineral said yesterday, however, that the evidence linking zeolites with the lung cancer in the Turkish villages is still sketchy.
Frederick Mumpton, a professor of mineral science at the state university of New York in Brockport, said in a telephone interview that he visited the two Turkish villages two weeks ago to collect dust and rock samples.
Mumpton said that while the villages - known as Karain and Turzkoy - did have zeolites in their dust samples, other villages that also showed te presence of the mineral did not have any evidence of mesothelioma in their populations.