Mesothelioma Risk in Some US Roads and Dust

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Driving on some of the roads in the United States may kick up dust containing high levels of erionite, a mineral that can increase the risk of developing mesothelioma, a type of lung cancer usually associated with asbestos exposure. At least 12 states, including North Dakota, Arizona, and Nevada, have rock deposits that contain erionite.

Some US roads may pose a cancer risk

The findings of a new study suggest erionite, a natural mineral fiber that has characteristics similar to those of asbestos, may be placing people at risk of developing mesothelioma in North Dakota, where erioniate-containing rocks have been used to make gravel for about three decades. The gravel was used to pave more than 300 miles of roads in that state.

Mesothelioma is a rare type of lung cancer that develops in the mesothelium, which is composed of parietal and visceral layers of tissue (membranes). The visceral membrane surrounds the lungs, and the parietal membrane is a sac that covers the visceral membrane. Mesothelioma is also called cancer of the lung lining.

People who develop mesothelioma typically do not get symptoms until 20 to 50 years after exposure to what caused the cancer. Asbestos exposure is the main cause of mesothelioma, and about 3,000 to 4,000 new cases of the disease are diagnosed each year in the United States.

According to Michele Carbone, MD, PhD, director of the University of Hawaii Cancer Center in Honolulu, and his scientific team from the Environmental Protection Agency, the National Institute of Environmental Health Sciences, and several universities, mice injected with the erionite from Dunn County in North Dakota showed the early signs of mesothelioma. Erionite can be found in other states as well, but the risk of exposure there has not been explored yet.

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In previous research in Turkish villages, Carbone had uncovered a relationship between exposure to erionite and abnormally high rates of mesothelioma. Those findings prompted him and his team to investigate the possibility of the same risks in the United States, where they found the fibers in the erionite from North Dakota to be similar in size to those found in Turkey.

When erionite fibers are disturbed, as they are when vehicles drive over rocks in which the mineral is found, the fibers can be released into the air and become lodged in the lungs of people breathing the kicked up dust. The level of erionite in the air in North Dakota was comparable to that found in Turkey, where a 6 to 8 percent death rate from mesothelioma has been reported in some villages.

Until recently, it was believed that erionite was present only in Turkey. The discovery of the mineral in the United States, where there are no established health benchmarks concerning safe levels of exposure to erionite, indicates that safety measures need to be taken.

Carbone noted that “based on the similarity between the erionite from the two sources, there is concern for increased risk of mesothelioma in North Dakota.” Because erionite have been mined in the United States only for a few decades, and given the long latency of the disease, it may be a long time before the true depth of this exposure is known.

However, these latest findings of possible risk of mesothelioma on US roads “provide an opportunity to implement novel preventive and detection programs in the US similar to what we have been doing in Turkey,” explained Carbone, where villagers were moved away from areas of high concentrations of erionite. Research is needed to identify other areas of concern in the United States, as well as ways to prevent and screen for mesothelioma.

SOURCES:
Carbone M et al. Proceedings of the National Academy of Sciences 2011 Jul 25; doi: 10.1073/pnas.1105887108
Mesothelioma and Lung Cancer organization

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