Asbestos is made up of microscopic fibers. These get detached, thus inhaled and these cling to tissues of the lungs. The fibers are too durable and does not breakdown or decompose, and they cause scarring and inflammation over time that can eventually develop into tumors.
There is no safe level of asbestos exposure. Most of the countries have banned asbestos completely, except the USA - but strict controls are in place for limited use.
Effects of asbestos takes many years to develop - say between 10 to 50 years and the three main conditions are,
Mesothelioma -aggressive cancer in the thin membrane (mesothelium) that protects vital organs in the chest and abdomen. Only asbestos can cause this condition.
Lung Cancer - the usual types of lung cancer
Asbestosis - A degenerative respiratory condition of forming scar tissue plaques on the surface of the pleura (lung linings). This can lead to mesothelioma later.
So asbestos is extremely dangerous and in the modern day has been replaced by other fiber materials.
In SriLanka the roofing sheets are cement based. I am not sure whether these contain the real asbestos even in a small proportion. There are asbestos cement sheets without real asbestos as well. Maybe someone in the industry or who knows can tell us what the situation is.
Asbestos is commonly found in the automotive industry (brake pads, brake linings, transmission plates etc - now these are made asbestos free) and also on several brands of Talcum Powder - Not only J&J.
There were several lawsuits against many companies.
The first suspicion came several decades ago in the 1970s when talc particles were detected in ovarian cancers. It took a long time and plenty of arguments till finally these lawsuits were filed in and compensation offered to the victims.
Another interesting factor to note is that the black gene is more resilient to Mesothelioma. The incidence among blacks is far less than the whites and the blacks who got mesothelioma lived longer than the whites.