Risk assessment for criteria pollutants vs. other non-carcinogens: The difference between implicit and explicit conservatism
Titel:
Risk assessment for criteria pollutants vs. other non-carcinogens: The difference between implicit and explicit conservatism
Auteur:
Beck, Barbara D. Cohen, Joshua T.
Verschenen in:
Human and ecological risk assessment
Paginering:
Jaargang 3 (1997) nr. 4 pagina's 617-626
Jaar:
1997-09
Inhoud:
The risk assessment methodology for the ambient air quality criteria pollutants (lead, ozone, particulate matter < 10 μm, carbon monoxide, nitrogen oxides, and sulfur dioxide) is based on the determination of an air concentration associated with minimally adverse effects in the sensitive subpopulation and setting exposure limits to protect most, but not all, members of the sensitive subpopulation. Thus, the target is comparable to a Lowest Observed Adverse Effect Level (LOAEL) with exposures set to ensure that the majority (typically > 95 %) of the sensitive population has exposures less than the LOAEL. In contrast, the target with the reference dose methodology is a No Observed Adverse Effect Level (NOAEL) for all populations, including sensitive subpopulations. In this analysis, we apply the reference dose methodology to two criteria pollutants, lead and ozone, and demonstrate that the resulting targets would be much more stringent than the actual standards. The targets would be, in the case of both lead and ozone, well below adverse effect levels and, in the case of ozone, well below ambient background exposures. Thus, this analysis demonstrates the conservatism of the reference dose methodology. The conservatism is due primarily to the risk target (the NOAEL) and the exposure goal (all exposures less than the reference dose). We recommend efforts should be directed toward improving the consistency between the two approaches.
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