Shift in Age and Gender Distribution of Mesothelioma Cases

For many decades, mesothelioma—an aggressive cancer that occurs in the mesothelium, the thin layer of tissue that covers the internal organs—has largely affected men age 60 and older.

But epidemiologist Francine Baumann of the University of New Caledonia has recently published a study indicating more cases of mesothelioma in women and younger people because of environmental exposure. Baumann’s study was published recently in the Journal of Toxicology and Environmental Health.

Occupational Asbestos Exposure Once Common in the U.S.

Mesothelioma is often connected to occupational asbestos exposure, though the disease may not develop for 20 to 50 years after asbestos exposure. Asbestos was once considered a “miracle mineral” because of its strength, and heat and fire resistance properties. During much of the 20th century, asbestos was used in a wide range of applications including insulation, brakes, fire resistant fabrics, shingles, ceiling tiles, wallboard, and flooring. But when asbestos fibers are inhaled, the fibers settle in the lungs or in the stomach, where they can cause irritation that may lead to mesothelioma. Parker Waichman notes that workers involved in asbestos mining and manufacturing were exposed to asbestos fibers, as were construction workers, auto mechanics, ship builders and others who used asbestos materials in their trades. These workers were overwhelmingly male, reports. But family members of people who worked with asbestos were also at risk from asbestos fibers carried home on a worker’s clothing.

Asbestos use has declined sharply since 1983 when the Occupational Safety and Health Administration (OSHA) set out restrictions on asbestos. The Environmental Protection Agency (EPA) banned new uses for asbestos, but asbestos is still found in many older buildings, including homes and schools. Federal, state and local authorities have developed asbestos abatement regulations to ensure that asbestos can be safely removed from buildings without exposing building occupants or workers to the dangerous fibers.

But with the decline of industrial and commercial uses of asbestos, researchers have noticed a shift in age and gender of mesothelioma cases.

Environmental Asbestos Exposure

Over time, natural deposits of asbestos can be disturbed through erosion, commercial development, and road construction. Dry conditions and wind can send asbestos fibers into the air, where they can be inhaled. According to U.S. Geological Survey maps, soil in California and other western states contains large deposits of asbestos and other fibrous minerals, Baumann said. Mexico, Greece, Turkey, Italy, Australia, South Africa and the island of Corsica all have the risk for environmental asbestos exposure.

Environmental exposure has become a primary cause for asbestos-related diseases in groups not associated with occupational asbestos exposure, according to Baumann says it is a challenge to study environmental asbestos exposure. People in regions with asbestos deposits may not even know they have been exposed. It is difficult for doctors and researchers to document personal histories of environmental exposure, Baumann explains. According to, about 3,000 cases of mesothelioma are diagnosed annually.

Baumann discovered a high incidence of mesothelioma in some tribal areas when she was in charge of the Cancer Registry in New Caledonia. There was no commercial use of asbestos in those areas. “These people were exposed to carcinogenic mineral fibers that were present in their environment,” Baumann said. The fibrous mineral Baumann found in New Caledonia was antigorite, which is not among the six regulated asbestos minerals. Antigorite is among the three most common serpentine minerals, along with lizardite and chrysotile, which comprises 90 percent of the asbestos used commercially in the world.

“With this study, I showed that mineral fibers, other than the six known asbestos, could be carcinogenic, and that a high percentage of women and young people among mesothelioma cases could be an indicator of environmental exposure,” according to Baumann’s study shows environmental asbestos exposure has significantly narrowed the gender gap in mesothelioma cases.

For the recent study, Baumann analyzed all mesothelioma deaths reports to the reported to the Centers for Disease Control and Prevention (CDC) from 1999 to 2010. Men born in the 1920s represented a significant portion of mesothelioma deaths. Deaths of younger people declined with time—suggesting a decline in occupation asbestos exposure. But the incidence of mesothelioma among women and their mortality rate increased over time, and this suggests increased environmental exposure.

Among occupational exposure mesothelioma cases, the sex ratio is generally 4-8 male cases for every one female case. With environmental exposure, it’s a 2-1 ratio. When both types of exposure exist in a certain area, the male to female ratio is less than 4-1.

Shift in Age and Gender Distribution of Mesothelioma

In 2015, Baumann and researchers at the University of Hawaii Cancer Center issued a report that linked environmental asbestos exposure to a growing number of mesothelioma cases in women and younger residents in southern Nevada. The researchers looked at the distribution of mesothelioma by sex and by age group, using government statistics and they analyzed soil, rock and air samples. The percentage of mesothelioma in females and younger people in southern Nevada was significantly elevated, compared to other Nevada regions and to the U.S., in general, Bauman said, indicating the likely environmental exposure to carcinogenic fibers.

Southern Nevada residents under 55 accounted for nearly double the percentage of mesothelioma deaths in that age group compared to the national average. The male to female ratio for the disease was significantly closer in this region. The study results are alarming for Las Vegas area, a city whose economy depends largely on tourism

Baumann said the first step toward dealing with the problem of environmental asbestos exposure is to identify the areas and populations most at risk for environmental asbestos exposure. The next step is “to communicate with local authorities and with the population in order to teach which materials may be dangerous, and how contaminated soils may be remediated.”

Legal Help for Victims of Asbestos-Related Diseases

If you have been diagnosed with mesothelioma or other illnesses associated with asbestos exposure, the attorneys of Parker Waichman LLP can offer guidance about your legal rights. To contact the firm for a free, no obligation case evaluation, fill out the online form or call 1-800-YOURLAWYER (1-800-968-7529).


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