Asbestos and The Lungs - What Happens When Asbestos Is In The Air We Breathe?
Asbestos fibers enter the body in the air we breathe. Most of the asbestos fibers we breathe - like other dust particles - are stopped long before they enter the small airways of the lungs. For example, when we enter a dusty room or sprinkle powder, we sometimes choke. We literally cough up the mucus that contains most of the irritating substances. However, because asbestos fibers are so small and thin, many of them pass all the way down to the small airways and alveoli (or air sacs.)
Once the fibers are inside the lungs, the body's defense mechanisms try to break them down and remove them. Despite these attempts, many fibers remain in the body and are potential disease-causing agents. Each fiber is a foreign body, rather like a splinter in a finger. Inflammations develop as the body tries to neutralize, break down or move the sharp, irritating fibers. These processes lead to the development of the various kinds of asbestos-caused diseases.
The body's defenses often coat these fibers with a layer of protein and they are then called "asbestos bodies." If a piece of lung tissue is stained with an iron stain these asbestos bodies become readily visible under a microscope. Finding enough of these asbestos bodies in lung tissue proves prior occupational exposure to asbestos, but it does not in itself prove that the person has an asbestos disease. (Also, not finding asbestos bodies does not prove that there was no prior exposure to asbestos.)
Click on A, B and C to see three microscopic slides of asbestos fibers lodged in the lungs.
Although all of the different kinds of asbestos fibers can be inhaled and become lodged in the lungs, some fibers (amphiboles, like amosite and crocidolite) seem to accumulate to a greater extent than others (such as chrysotile.) This might be because some chrysotile fibers, being long and curly, get stuck higher up in the lungs rather than transported all the way into the small airways. Or it might be because chrysotile fibers, being fragile and unstable, break up in the body within a few months and are transported away from the lungs into the pleura or lymph system.
Once fibers are inside the body, they can move around. How this happens is not fully understood. It might be because they are thin and sharp. The fibers can move from the lungs into the pleura and into the lymph nodes, and this means that they can move into other parts of the body.
Finally, asbestos can be swallowed (ingested) as well as inhaled. For example, when mucus and sputum that contain a lot of fibers are swallowed, some of those fibers can stick in the intestinal tract and from there they can move into the lining of the abdomen (peritoneum.)
However, when we are healthy, breathing is easy - so easy we don't even think about it.
