In 1990, the Clean Air Act (CAA) Amendments authorized the regulation of 188
hazardous air pollutants (HAP). Exposure to HAPs at sufficient concentrations and
durations can increase both cancer and serious adverse non-carcinogenic effects. The
purpose of this study was to conduct a human health risk assessment using data of 43
HAPs from five monitor sites in Portland, Oregon during July 1999-August 2000.
HAP concentrations were compared to carcinogenic and non-carcinogenic
(health) benchmark concentrations; and emission sources were determined for HAPs that
exceeded health benchmark concentrations. Additionally, cancer risks were determined
for subpopulations and compared to cancer risks generated for the general population.
Results of this study indicate that 20 HAPs exceeded carcinogenic benchmark
concentrations (corresponding to a risk level of 1 x 10������) in at least one location.
Chromium compounds posed the highest cancer risk (3.5 x 10������). Seventeen HAPs
exceeded carcinogenic benchmark concentrations at all five sites. Seventy-five percent
(%) of the total cumulative cancer risk was contributed by chromium compounds, 1,3-butadiene, formaldehyde and 1,1,2,2-tetrachloroethane. Three HAPs, chromium compounds, acrolein, and formaldehyde, exceeded non-carcinogenic hazard ratios of 1.0.
Releases from area sources accounted for the largest percentage of HAPs that exceeded
health benchmark concentrations.
With respect to subpopulations, asthmatics teenagers (age 11-16) and asthmatic
adults (age 18-50), had slightly elevated cancer risks of 1.4 x 10������ and 1.2 x 10������.
respectively, compared to the general population risk level of 1 x 10������.
Results of this study indicate that several HAPs pose a potential human health
concern in Portland and that efforts should be made to reduce their emissions. Additional
studies are warranted to further assess potential human health risks and the extent of
HAPs in Portland, Oregon. / Graduation date: 2003
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/31593 |
| Date | 03 February 2003 |
| Creators | Tam, Bonnie |
| Contributors | Neumann, Catherine |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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