|1. What are the media concentration or exposure results? |
|Concentrations of the VOCs were rather uniform among the sites. Concentrations were statistically significantly higher at one site for tetrachloroethene, and lower at one site for toluene and o-xylene. The tetrachloroethene sources were two dry cleaners and a pumping station at a publically owned treatment facility.|
For chemicals included in the quantitative risk assessment, the annual average concentrations measured in this study were generally in the same concentration ranges as those for other urban areas nationwide. For chromium, nickel, cadmium, and vanadium, concentrations were higher in this study than in other urban areas. This is based on comparison to the EPA Urban Air Toxic Monitoring Program (UATMP) results for 1988 and 1989.
The indoor air study showed that concentrations of 13 VOCs in four houses were generally similar to concentrations in several other databases for indoor air. Concentrations of 8 VOCs, including toluene and benzene, were usually higher indoors than outdoors.
|2. What are the individual cancer risk estimate results? |
|The cumulative cancer risk estimate was 96 or 123 per million, depending on the assumption concerning ambient air concentrations of hexavalent chromium.|
|2.a. What is the cancer risk estimate for the maximum exposed individual (MEI)? What HAPs drive the risk? |
|2.b. What is the maximum individual risk (MIR)? What HAPs drive the risk? |
|3. What are the individual non-cancer risk estimates: MEI, MIR, worker? What HAPs drive the risk?|
|4. What are the target-organ specific hazard indices (TOSHI)? If they weren't developed, why not?|
|5. What are the population risk results? |
|6. What other results were found as part of this project? |
|The estimated cancer and noncancer toxicity risks associated with benzene were consistently higher than those estimated for the other pollutants. The next highest risk for ambient air exposure were associated with nickel, chromium, arsenic, and tetrachloromethane.|
The additive risk assessment yielded a maximum hazard index of 2 for noncancer toxicity; the effects were blood formation problems and respiratory tract irritation.
|7. What pollutants were identified as being of concern? On what basis? |
|The cancer risk drivers are benzene, formaldehyde, chromium, tetrachloromethane, trichloromethane, and cadmium. The noncancer risk drivers are benzene, nickel, chromium, and tetrachloromethane.|
|8. What sources of pollution were identified as being of concern? |
|Mobile sources, refineries, and gasoline stations for their contributions to benzene. Dry cleaners and pumping stations of Publically Owned Treatment facility for their contributions to tetrachloroethene.|