Asbestos Exposure and Cancer Risk
Asbestos is a naturally occurring group of minerals which can be found in rocks all over the world. It consists mainly of oxygen and silicon and divides into two main categories:
- Chrysotile asbestos or white asbestos. This is the most common type of asbestos and has been used in industrial applications for a long time.
- Amphibole asbestos. These fibers look like needles and can be classified in more categories such as amosite, tremolite or crocidolite.
The Use of Asbestos
Asbestos has been used as a construction material since ancient times and both types of fibers have been discovered to cause cancer. Before the regulation of asbestos use in 1970, people were highly exposed to asbestos fibers both at home and at the workplace. In the second half of the 20th century, a decrease in the use of asbestos has been reported as laws and exposure standards have been created. By that time, though, hundreds of people have already been exposed to high levels of asbestos and developed cancer. Moreover, an important use of this material still continues in some countries.
There are two types of asbestos exposure which can cause serious health problems:
- Inhale. When the asbestos fibers become airborne, they can be easily inhaled. This can happen during mining processes or even when renovating a house. If the asbestos-containing materials are damaged, the fibers create a dust which put people at risk of developing cancer due to asbestos exposure.
- Swallow. These fibers can be swallowed, as well, when contaminated food or water is consumed.
People can be exposed to extremely low levels of asbestos through the outdoor air which contains particles resulting from the asbestos-containing rocks' erosion. However, those who work in the construction industry have the highest risk of being exposed to asbestos. Their families are not safe, either. Family members can be easily exposed to the harmful fibers which are carried home on clothes.
It is very important to know that undamaged asbestos-containing products and materials present no health risk. As long as the fibers are not released into the air, there is no risk of being exposed to asbestos.
Two Type of Studies Have Been Done in Order to Find out if Asbestos Can Cause Cancer
- The first study is based on comparing cancer rates of people belonging to different groups. Therefore, cancer rates of people who have been exposed to asbestos have been compared to those of people who haven't been exposed.
- The second type of study has been done in the laboratory and consisted in exposing animals and normal cells to asbestos in order to see if they develop cancer.
Results of both studies have shown that exposure to asbestos can highly increase the chances of developing several types of cancer. Asbestos fibers that get into the lungs can irritate cells and, consequently, cause mesothelioma or lung cancer.
Another pattern has been discovered: the greater the exposure, the higher the probability of developing lung cancer. The average time from the first exposure to the occurrence of the disease is 15 years. Moreover, smoking can increase the risk of lung cancer for those who have been exposed to asbestos.
Mesothelioma is also linked with the exposure to all forms of asbestos, although amphibole fibers seem to cause cancer even at low levels of exposure, unlike chrysotile fibers. It usually takes a very long time for mesothelioma to develop and to be diagnosed, around 30 years. The time that has passed after the exposure and smoking have no influence on the risk rate and no safe level of asbestos exposure has been determined.
Studies have found links between asbestos exposure and cancer of the larynx, ovaries, stomach and colon, as well. Still, a certain influence has not been established as it is not clear yet how the exposure can lead to the development of these types of cancer. Swallowed fibers are thought to contribute to this risk somehow.