Mesothelioma

Amidst mounting environmental health concerns, researchers are taking a closer look at natural carcinogens. Commercial use of these substances increases the amount and risk of exposure, and these environmental hazards can also cause cancer.

One such concern is asbestos, a group of six silicate materials once hailed as the “miracle mineral” for their versatility, and now linked to a rare and deadly cancer: mesothelioma.

Though government bans have minimized risk, the widespread existence of asbestos in the environment and man-made world mean that the danger cannot be truly eliminated, prompting scientists to reexamine the risks these natural deposits pose to the public.

“A lot of people are not very educated about asbestos; they think it’s something old that we don’t have to worry about anymore because we’re not building with it frequently, but that’s not the case,” says Dr. Brenda Buck, Professor of Geology at the University of Nevada, Las Vegas.

Natural asbestos deposits are found across the U.S., largely in California and the Appalachian Mountains. In a 2011 report, the United States Geological Survey mapped 113 locations of naturally occurring asbestos across the southwestern U.S. including Arizona, Nevada, and Utah. Buck fears that undiscovered sites could drive those numbers higher.

Buck and her colleague, Dr. Rodney Metcalf, first grew concerned about Nevada’s naturally occurring asbestos, or NOA, in 2013, when they linked increased risk of mesothelioma, asbestosis, and other diseases to heightened levels of the toxic fibers in rocks and soil surrounding Boulder City. These fibers were similar in shape and size to those found in Libby, Montana, a town devastated by asbestos-related cancers and mesothelioma decades after the closure of its asbestos mine. Buck and her colleagues say natural deposits like these pose a latent risk and fear Nevada residents could face similar danger.

“Here, because we’re in the Mojave Desert—the driest part of North America—natural processes like wind can get these particles in the air. In places where the soil is moist and there’s a lot of vegetation, the risk is much lower because you have to work harder to get those particles into the air,” Buck says. Following these revelations, officials halted construction on Interstate 11 in the summer of 2013.

Air quality tests in El Dorado Valley displayed airborne concentration levels an average of 2.3 times higher than the Environmental Protection Agency’s Reference Concentration (RFC) regulations for asbestos.

Despite these results, construction resumed, with workers using water to minimize dust throughout the process. Buck fears even this number may not be representative of actual risk, given how human activity can change the risk of exposure for each family in the Valley. She says those numbers may be harder to learn, due to lack of funding and government pushback. 

“No one is really interested in funding asbestos research. We haven’t been able to quantify the risk because we haven’t been able to quantify the exposure. It’s not rocket science, it’s just money,” she says.

For now, progress comes slowly. Last fall, Buck worked with Dr. Jean Pfau of the University of Montana to study the effects of NOA from Lake Mead on mice. Even at low doses, the animals became sick. What’s more, Buck says, researchers are still learning the ways in which NOA affects health differently than commercial asbestos. Commercial asbestos is often associated with mesothelioma, while certain NOA amphiboles cause autoimmune diseases. Chrysotile asbestos is usually curlier and more flexible, while amphibole asbestos is generally sharper and more needle-like, according to Buck. These nuances make it difficult to fully understand the risks, though Buck believes that amphiboles may be even more dangerous than other forms.

“If we lump these together in research, we won’t get a clear answer because they’re behaving in opposite ways,” Buck says. “It also impacts our regulations and even what we call asbestos. There are different types of risks.”

In the rest of the country, individuals remain most at risk of encountering commercial asbestos in their home or work environment, rather than in the outside environment.

Asbestos was a common building material for decades, and in older buildings that have not been renovated, the substance may linger.

“As a rule of thumb, any building built prior to 1980 most likely has asbestos in it somewhere,” says Nick, an asbestos professional who has been teaching abatement certification courses for nine years. “It can be in drywall, ceiling tiles, and floor tiles; not only in insulation.”       

When asbestos becomes friable, or easily crumbled in the hands, the likelihood of someone inhaling it increases; this risk could be exacerbated in aging buildings, as the asbestos deteriorates. The microscopic fibers are most deadly when airborne and can develop into cancer in anywhere from 10 to 50 years. According to standards set by the Environmental Protection Agency, asbestos does not constitute a threat unless it is disturbed.

“Usually the best thing is to leave asbestos-containing material alone if it is in good condition,” says Robert Daguillard, EPA spokesman. “Generally, asbestos-containing material that is in good condition, and will not be disturbed, will not release asbestos fibers.”

In fact, professional removal and disposal is required for any existing asbestos that is disturbed during renovation or demolition, mostly in places like schools and public buildings. Abatement professionals must attend a certification course and follow strict removal procedures. This process can itself increase the risk of releasing harmful asbestos dust into the environment, so professionals rely on EPA regulations to maintain safety.

“The purpose of these work practices is to minimize the release of asbestos into the environment, with special emphasis on minimizing the release of asbestos into the ambient (outside) air,” says Enesta Jones of the EPA.

During removal, teams of industrial hygienists routinely test air quality to adhere to OSHA standards of less than 0.1 percent asbestos particles in the air over an eight-hour workday. That limit drops to 0.01 percent after removal is completed.

“You actually return the workspace cleaner than you found it,” Nick says. Building Operations and Management programs often have an inventory of materials used in the building, but such lists are not always available.

Asbestos removal also carries the potential to release harmful fibers into the environment, kicking up dust that may then spread to other areas. To combat this effect, the Asbestos National Emissions Standards for Hazardous Air Pollutants (NESHAP) requires that abatement professionals wet asbestos before removal to prevent dust, and use specific sealed containers to store and transport the asbestos. Abatement professionals seal removal sites to contain dust, and adhere strictly to the guidelines in order to be as safe as possible.

Despite these regulations, Buck and her colleagues remain concerned about naturally occurring asbestos deposits. Without a complete ban, and with natural asbestos posing an environmental hazard, she says the immediate goal is simply mitigation. For now, natural asbestos seems to be an environmental hazard that residents must learn to manage. Its prevalence may require changes to the ways in which we interact with the world. For example, Buck says, new information may lead to changes in where residents hike, camp, or ride their bikes in order to avoid areas with heightened asbestos risk.

“Risk management rather than risk elimination is what we have to do,” she says. “It’s in our environment and we can’t control the natural processes that stir it up. All we can do is change our behavior to lower that risk.”