Dust and Human Health - Mineral Dust: A Key Player in the Earth System - page 394

Autopsy reports have documented mineral grains in the lungs of farmworkers
(Gylseth et al. 1984 ; Pinkerton et al. 2000 and Domingo-Neumann 2009 ), a finding
that belies long-held assumptions that MD particles were too large to be respired.
Pinkerton et al. ( 2000 ) examined lungs provided by the coroner's office of young
individuals who had been primarily employed in agriculture, but who had died
from unrelated causes; they found evidence of mineral dust retention and associated
small airway disease (26 %), pneumoconiosis (10 %), lymph node fibrosis (38 %),
and asthma (33 %) in lungs on autopsy. Schenker ( 2000 ) suggests the magnitude
of the exposures to agricultural dusts may be a clinically significant etiological
component. This is in agreement with the concept of biopersistence, which may
lead to accumulation and/or overload and longer retention times.

15.5.5 Other Potential Risks Related to MD Exposures:

Pneumoconioses

The inhalation of certain mineral dusts through occupational exposures has been
recognized since the 1930s as a precursor to the development of pneumoconioses
(McClellan 2000 ). This term which describes a group of interstitial lung diseases,
such as silicosis, is still endemic in some areas of the world where dust control
and protective measures are not adequately implemented, notably China (WHO
2013 ). As an occupational disorder, silicosis has been well studied and is associated
with tuberculosis (teWaterNaude et al. 2006 ) and lung cancer (Attfield and Costello
2004 ).
Nonindustrial silicosis, or desert lung syndrome, has not received extensive
scrutiny. It has been recognized in North Africa, the Middle East, China, and India
(Policard and Collet 1952 ; Hirsch et al. 1974 ; Norboo et al. 1991 ;Xuetal. 1993 ;
Mathur and Choudhary 1997 ; Derbyshire 2007 ). It is difficult to ascertain how
widespread desert lung is, as cases may not be reported or diagnosed, depending
in part on health services available. Further, in some areas of the world, large
population-based studies would be problematic because diagnosis is made by
radiographic findings of silicotic nodules in the lungs and history of exposure to
airborne silica dust.
No current related research was identified; however, available studies found the
incidence of nonindustrial silicosis to be greater in women than in men (Hirsch
et al. 1974 ; Norboo et al. 1991 ) and identified an association between desert
lung syndrome and cataracts (Hawass 1987 ). Xu et al. ( 1993 ) observed that the
prevalence of siliceous pneumoconiosis in residents near a desert area in Gansu
Province was 7.09 %, less than the rates for occupational exposures in South African
gold miners (18-19 %, Churchyard et al. 2004 ) but comparable to that of surface
coal miners in Pennsylvania (3.7-9.7 %, CDC 2000 )(Fig. 15.4 ).
A related disease, Al Eskan, or desert storm pneumonitis, was recognized
in troops deployed to the Persian Gulf in Operation Desert Storm in 1991