There is some understanding of the etioloy, but the basis for mesothelioma formation is unknown.
Asbestos is inert in natural rock form. For it to be hazardous, it must be turned into fine flakes of dust that can be inhaled. So there is a risk in mining, milling, and abatement activities with friability.
Respirators make effective safety devices. However, dust and fibers go home on the clothing of workers. Self exposure, family exposure: there is a ten times increased risk of mesothelioma in women who live with asbestos workers.
Science has shown that the hazard depends on particle size.
Length of fibers: 2 microns: asbestosis
5 microns: mesothelioma, asbestosis
10 microns: bronchogenic lung cancers associated with cigarette smoking and asbestosis.
Over 3 microns: no mesothelioma
Less than 0.5 microns: mesothelioma