US EPA

3099951 

Technical Report 

Asbestos Risk Assessment: The Ontario Royal Commission View 

Dewees, DN 

1987 

NIOSH/00170709 

Its Health Risks 

216-227 

The conclusions of the Ontario Royal Commission concerning the health effects of asbestos, the use of models for risk assessment, the magnitude of risk to occupants posed by asbestos in buildings, and the regulatory philosophy required to limit risk were presented. With regard to the health effects, the commission concluded that while exposure to low levels of asbestos will not result in asbestosis, evidence on risks from low exposure with respect to lung cancer and mesothelioma are inconclusive. The assumptions involved in dose response risk assessment models were discussed. The commission stated that when assessing risks in a particular situation they use the dose response coefficients from the most nearly comparable epidemiological study. The commission concluded that the exposure of building occupants to asbestos fibers was extremely small if the asbestos was in good condition and not disturbed, and that there was a correspondingly small health risk to those individuals. They also concluded that precautions were required to maintain acceptable levels of exposure for building workers whose activities might disturb friable asbestos insulation. The commission expressed concern that unreasonable risks arising from building exposure should be avoided and that public fear should not lead to extravagant expenditures in pursuit of very little or no reduction in risk. The commission concluded that the low level of risk present in buildings does not warrant programs of universal asbestos removal nor universal inspection of buildings for asbestos.