Three diseases account for most of the adverse health effects
resulting from mineral inhalation: fibrosis, lung cancer,
and mesothelioma [ Kane, 1993]. Fibrosis is a
non-malignant disease characterized by the excess production of
collagen which results in a stiffening of the lung. Fibrosis
reduces the efficiency of the lung and, hence, strains the
heart. Lung cancer arises from transformed epithelial
cells in the respiratory tract, and it can result from
exposure to minerals as well as many other agents
(principally cigarette smoke). Mesothelioma is a
cancer of the pleura and, in humans, is almost always
associated with exposure to fibrous minerals (asbestos and
more recently erionite, a naturally occurring, fibrous
zeolite). Mesothelioma has only a very low incidence among
populations that are not occupationally exposed to asbestos
(e.g., 
1 in 10
in the general population) [ Kane,
1993].