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I <br /> 6.31 Noncarcinogenic Risk <br /> Table 6-2 shows the hazard indexes (HI) for noncarcinogenic effects for all exposure <br /> scenarios. A total HI of 1 or less indicates that there is no cause for concern for adverse , <br /> noncarcinogenic health effects. The HI approach for noncarcinogenic chemicals assume <br /> that simultaneous subthreshold exposureto several chemicals could result in an adverse <br /> health effect. <br /> Results for human health. risk. assessment indicate. that the noncarcinogenic hazard <br /> indexes are below the EPA level of concern (1.0) for all exposure pathways and all j <br /> receptors evaluated for the site. Combining exposure pathways for each receptor'also <br /> resulted in hazard indexes substantially below the level of concern (Table 6-2).. <br /> L` <br /> The hazard index for current and future occupational employees was 1.0E-09 for RME <br /> and 1.0E-09 for average (Tables 6-3 and 6-4). The highest hazard was from inhalation <br /> x <br /> during showering. The chemical that was responsible for the.hazard was xylene. <br /> The hazard indexes for hypothetical adult residents were 4.5E-05 and 1.3E-05:for RME <br /> and average, respectively (Table 6-5 and 6-6). The highest hazard was from inhalation <br /> / duringshower of toluene and xylene. The hazard indexes for hypothetical child residents . <br /> xy YP <br /> were 1.1E-04 and 2.6E-05, respectively (Table 6-7 and 6-8)where the highest hazard was <br /> also from inhalation during shower of toluene and xylene. For the seasonal high <br /> groundwater RME child scenario the highest hazard (9.9E-05) was from ingestion of <br /> drinking water. <br /> In summary the hazard indexes are all significantly below one, the level of concern, even <br /> though conservative assumptions were used in the fate and transport modeling and <br /> exposure assumptions. <br /> I <br /> S:\LDC\YELLO.Pn May 4, 1995 6-8 <br />