Despite being banned in the United States since the 1970s, asbestos can still be responsible for new cases of lung cancer today.

Asbestos is a naturally-occurring fibrous mineral with properties that make it useful in a wide variety of industrial applications, such as insulation, fireproofing, and sound absorption. Medical science has been aware of a link between asbestos exposure and lung cancer since 1935.

Any physical disturbance of asbestos releases microscopic asbestos fibers into the air. If a person inhales those fibers, the fibers can become lodged in respiratory tissue. Smaller fibers tend to lodge in the lining around the lungs and are more likely to lead to mesothelioma; larger fibers are more likely to lodge in the lung tissue itself and lead to lung cancer.

Once the fibers are lodged in lung tissue, they remain there, causing inflammation, scarring, and other problems. Over time – generally decades – the damage leads to formation of tumors.

Whether asbestos exposure leads to lung cancer depends on the duration of exposure and how much asbestos is involved. For patients chronically exposed to asbestos, as in work-related exposure, the risk of lung cancer increases as much as 4 percent per year of exposure.

Smokers exposed to asbestos have a much higher risk of developing asbestos lung cancer; researchers believe that smoking reduces the lungs’ ability to expel asbestos fibers, causing more fibers to accumulate faster and increasing the risk of cancer by as much as 84 percent.

A hallmark of asbestos-related diseases is that they take decades to develop. In the case of asbestos lung cancer, the latency period, or time between the initial exposure to the onset of illness, typically takes 15 to 35 years. So even today, several decades after asbestos was banned in the United States, new cases of asbestos lung cancer can appear that were caused by exposure back in the mid-20th century.

Despite the very long latency period, once lung cancer is well-established, it can spread to other parts of the body in a matter of months. Unfortunately, the prognosis for asbestos lung cancer is poor. Even with treatment, the median survival time runs from several months to just a few years.

Work-Related Asbestos Exposure

Because asbestos was useful in so many applications, its use was widespread through the mid-20th century. The shipbuilding industry in particular used asbestos as insulation for boilers and pipes, and the same industry was notorious for exposing workers to asbestos through lax safety practices.

The U.S. military also exposed service members through widespread use of asbestos in vehicles and buildings. Automotive applications of asbestos include brake shoes and clutch pads, exposing auto builders and mechanics to asbestos. A broad variety of construction materials were also made with asbestos, including insulation, ceiling tiles, floor tiles, paints and adhesives. The jobs that carried the highest risk for asbestos lung cancer are those where workers were in the presence of asbestos in a confined space.

U.S. regulatory authorities began banning asbestos in the 1970s. The ban culminated in a 1989 ban by the EPA on all new uses of asbestos, though the EPA did not ban uses developed before then. Indeed, trace amounts of asbestos can still be found in some consumer products today, sometimes in products that also contain talc or vermiculite. However, studies by the EPA and the Consumer Product Safety Commission in 2000 concluded that the risk of asbestos exposure from these products is extremely low.