Risk characterization for silica-related silicosis and lung cancer in communities adjacent to sand and gravel extraction facilities: examining limitations in our current risk methods

Risk of silicosis and lung cancer due to community exposures to RCS need to be addressed in the context of observable increases of disease in populations exposed to low to moderate levels of RCS. Direct epidemiology studies of community exposures are lacking, but no clear indication of concern based on lung effect prevalence has been reported. In the absence of such data, extrapolations for risk assessment using occupational epidemiology data as a basis for potency estimates are used and need further adjustments. Application of such adjustments would likely support a conclusion that community exposures do not exceed the threshold necessary for carcinogenesis to observe elevated levels of lung cancer or for silicosis. This analysis supports a modified HQ or modified Margin of Safety (MOS) approach with additional modifiers including inhalation dosimetry, exposure intensity and potency that address differences between occupational and community exposure scenarios.