While cigarette smoking is the most important risk factor for lung cancer, asbestos exposure is also an important factor. Inhaled asbestos and smoking work together synergistically to cause lung cancer. The risk of lung cancer in a smoker that has been exposed to asbestos is higher than the risk of the two factors combined. In other words, smokers and those exposed to asbestos each have about a 5 to 10-fold increased risk to develop lung cancer. However, people that were exposed to asbestos and smoke, are 50 to 100 times more likely to develop lung cancer.
Several factors influence the magnitude of the risk of asbestos-related lung cancer. The rate increases with:
About one in seven people with asbestosis develop lung cancer. Asbestosis is a fibrotic lung disease caused by breathing asbestos fibers. Asbestosis is an independent risk factor for lung cancer; it increases lung cancer risk in the absence of other risk factors (like smoking). There are approximately 200,000 people with asbestosis. Approximately 2,000 people die of asbestosis each year and an additional 2,000 to 3,200 people die of asbestos-related lung cancer.
Asbestos is a group of minerals that exist naturally as fibers. In fact, asbestos is the smallest naturally-occurring fiber. It is a silicate, which means it contains a silicon atom and four oxygen atoms. Asbestos occurs in crystals of two major forms: serpentine (of which chrysotile fibers are the only major form) and amphibole. Chrysotile fibers are long, curly and easily bend while amphibole asbestos fibers are short, stiff and straight. The amphibole type of asbestos fibers is found in the soil of many countries, especially in Europe and northern Asia. Chrysotile fibers were the main asbestos fiber type used for commercial applications the United States, which amounts to approximately 95% of all commercial applications.
The reason that asbestos was used so extensively over the last two centuries is that it highly resistant to damage from heat and corrosion. It does not conduct electricity either making it an excellent insulator. Asbestos is quite durable but also flexible. Moreover, asbestos is relatively inexpensive to obtain through mining. If asbestos was not associated with such horrible lung diseases, such as lung cancer, it was and would be an incredibly useful material.
Asbestos was used in thousands of different applications over the past decades. Asbestos was used when a durable material was needed to stand up to repeated wear, electricity and high heat. Asbestos was commonly used in shipping materials, building materials and electrical products. It was used in various modes of transportation as well including airplanes, railroads/trains, ships and automobiles (especially in parts like brake pads, clutch linings and gaskets).
When asbestos was commonly used, there were dozens of professions that included duties in which asbestos exposure was possible or likely. Obviously asbestos miners, those that transported asbestos and those that weaved asbestos fibers into fabrics had extremely high exposure rates. Workers that used asbestos for insulation or those who removed asbestos-containing insulation were greatly affected as well. Contractors, tradesman, and laborers that worked with asbestos also had high exposure rates.
When asbestos is in its stable, undisturbed state, it is not hazardous to health. Unfortunately, working with the material in almost any way, can disrupt the asbestos, causing fibers to become airborne. When asbestos particles are dispersed, they are inhaled and become embedded in the lungs.
Even moderate and small exposures to asbestos have been linked to serious diseases of the lung, including cancer. Many professions in which asbestos contact was limited or indirect are still associated with relatively high rates of lung cancer and other asbestos-related disease. Automobile mechanics, janitorial staff, factory workers, and demolition crews may have received a reasonably large exposure. In fact, the spouses of workers with particularly high exposure professions have been exposed to disease-causing amounts of asbestos. They inhaled asbestos fibers from clothing and other items belonging to the directly exposed.
We can help you figure out if you were exposed to asbestos. We have a database of products that employed asbestos over the years, and a list of workplaces and occupations where exposure was likely to occur. If you have lung cancer and were exposed to asbestos in the past, you may have a legal case.
Asbestos has been linked to a number of lung diseases including asbestosis, pleural plaques/effusions, and mesothelioma. Asbestos is also an important cause of small cell and non-small cell lung cancer. There are a number of lines of evidence that asbestos is clearly linked to lung cancer including laboratory, epidemiological, and clinical research. Among medical professionals, asbestos is now universally accepted as a cause of lung cancer.
DNA damage is the hallmark of the cancerous transformation of cells. Asbestos fibers have been shown to be able to kill cells, delete large stretches of DNA from a cell’s genome, and damage chromosomes (bundles of DNA that make up the genome). The silicate fiber may cause DNA damage through oxidative damage because antioxidants can reduce the damage in laboratory studies. Asbestos contributes to inflammation and fibrosis, which may exacerbate cancer formation/propagation.
The clinical evidence linking asbestos to lung cancer dates back to at least the 1930s, though an association was theorized in the 1890s. The original epidemiological evidence began appearing in the scientific literature in the 1950s. It was found that asbestos textile workers in India were ten times more likely to develop lung cancer than matched controls. In the United States, the increased lung cancer risk in asbestos insulation workers was found to be sevenfold.
It became clear that the risk of lung cancer increases in a dose-dependent fashion. In other words, people with higher or longer exposure to asbestos fibers have a higher the risk of developing lung cancer. This is considered more or less definitive evidence of a causal link from an epidemiological perspective.
In the United States, there are two main agencies that are tasked with the duty of making and enforcing regulations regarding asbestos. The federal agency that is responsible for regulating air pollutants is the Environmental Protection Agency (EPA). Under the Clean Air Act, the EPA must provide guidelines about emission rates. The EPA is also responsible for regulations covering asbestos in schools.
The other agency that is responsible for asbestos regulation is OSHA or the Occupational Safety and Health Administration. OSHA is responsible for protection and safety of workers. OSHA is concerned with the protection of workers that may have been/are exposed to asbestos in the course of their professional duties or in their work environment. There is important overlap and redundancy between the EPA and OSHA when it comes to asbestos regulation.
The notion that asbestos was an important cause of human disease was considered in the late 19th century; however, asbestos was not regulated to any significant degree in the United States until the 1970s. Originally the asbestos fiber exposure limits were set at 5 fibers per cubic centimeter in 1971. In 1994 this limit was revised to 0.1 asbestos fibers per cubic centimeter. In 1989, The EPA banned all new uses of asbestos in the United States.
Since it is clear that the risk of asbestos-related diseases increases with increased exposure, the goal of asbestos disease prevention is to limit exposure. Undisturbed asbestos is not dangerous; therefore it is often better to leave existing asbestos in place and prevent it from being disturbed rather than removing it. The risk to the asbestos workers and the resulting spread of the asbestos in the environment during removal may outweigh the risk of exposure from stable asbestos. The EPA and OSHA can be called upon to make case by case recommendations as to whether asbestos should be removed or secured.