Naturally Occurring Asbestos is Common in Ultramafic Rock

Mesothelioma News

Naturally Occurring Asbestos May Increase Mesothelioma Risk, Study Suggests

DAVIS, CA — July 8, 2005 — Californians who live closest to deposits of naturally occurring asbestos have an increased risk of developing mesothelioma, an aggressive cancer caused by exposure to asbestos, a new study suggests (Am J Respir Crit Care Med. 2005 Jun 23). The authors note that this conclusion is in line with reports of links between mesothelioma and environmental asbestos exposure in Cyprus, Greece, New Calendonia, Corsica, China, and Italy.

The researchers looked at data from the California Cancer Registry on 2,980 cases of mesothelioma diagnosed between 1988 and 1997 . They compared these patients to a group of pancreatic cancer patients of similar age and sex. They took subgroups of patients over the age of 35, and considered how far they lived from “ultramafic” rock. Ultramafic rock is formed from molten rock. It contains only small amounts of silica and large amounts of magnesium and iron. The main source of naturally occurring asbestos in California, ultramafic rock is found in the the fault zones in the low Sierras and in some of the state’s coastal towns.

The study showed that the odds of having mesothelioma decreased about 6.3% for every 10 kilometers (6.2 miles) distance from ultramafic rock. The result was especially significant for pleural mesothelioma, a form of the cancer that attacks the membranes surrounding the chest and lungs.

Can Naturally Occurring Asbestos Account for “Unexplained” Mesothelioma Cases?

We know that occupational exposure to asbestos can cause mesothelioma. The current California study adjusted its analysis for age, sex, and on–the–job asbestos exposure. High risk categories included shipyard workers, insulators, plumbers, steamfitters, and boilermakers. Moderate risk occupations included mechanics, electricians, sheet metal workers, welders, sailors, navy servicemen, and construction laborers.

The study was limited by the California Cancer Registry, which sometimes gave only the last workplace exposure and did not always have full job records. A complete residential history was also sometimes lacking. Still, the statistics were significant enough to show a definite trend for mesothelioma victims. Also, the California Cancer Registry is one of the largest, most comprehensive cancer registries in the world, according to the researchers, covering the entire population of the state or more than one tenth of the US population.

The authors suggested that more research be done to account for other factors that could affect mesothelioma: the age when someone was first exposed to asbestos, the rock deposit size, the duration of a person’s residence, and various types of activities such as construction that disturb the ultramafic rock. They believe that contact with asbestos from the environment, the home, or the neighborhood may help explain those cases of mesothelioma that do not seem to be related to occupational exposure.

At Brayton Purcell, we are concerned about asbestos on the job, in the home, and in our environment. If you have been diagnosed with mesothelioma or another asbestos–related disease, please feel free to contact us to discuss your legal rights. We have been successfully handling asbestos litigation for over 20 years.