ARCHIVED REPORTS XR0000211 - Laserfiche WebLink

Home Browse Search

SECTEONEX Risk Chereeterizetl®u the risk was inhalation of volatiles from soil and groundwater This pathway assumed that there would be no paving at the Shop 10 site The chemical that had the largest contribution to the cancer risk in groundwater ingestion was benzene(Table 6-2) In summary, inspection of Table 6-1 and Table 6-2 shows that direct soil exposures and inhalation of volatiles for occupational employees comprises the chief risk at the site (1 5E-06 using the oldest groundwater data from Table 3-4) The numbers were calculated using worse-case assumptions which would increase the possible groundwater concentrations (i e, large biodegradation half lives of 100,000 days, no asphalt or concrete paving, shallow groundwater elevation, etc) 6.3.2 Noncatcinogenic Risk Table 6-3 shows the HI for noncarcinogennc effects for all exposure scenarios A total M of 1 or less indicates that there is no cause for concern for adverse noncarcinogemc health effects The HI approach for noncarcinogemc chemicals assume that simultaneous subthreshold exposure to several chemicals could result in an adverse health effect Results for human health nsk assessment indicate that the noncarcinogenic hazard indexes are below the EPA level of concern (1 0) for all exposure pathways and all receptors evaluated for the site Combining exposure pathways for each receptor also resulted m hazard indexes substantially below the level of concern(Table 6-3) The hazard index for current and future occupational employees ranged from 2 7E-02 to 3 4E-02 (Table 6-3) The highest hazard was from direct soil exposures, soil ingestion and dermal exposures The hazard indexes for hypothetical adult residents ranged from 2 OE-04 to 7 2E-04, with the higher values associated with the resident being located 500 feet downgradnent of the site (Table 6-3) The hazard index from groundwater ingestion ranged from 2 4E-32 for a well located 500 feet downgradient using the groundwater data from 1987 to 1992 to 3 6E-57 for a well located at 1,000 feet downgradnent using all of the site's groundwater data The chemical that contnbuted the largest to the hazard was benzene ' In summary the hazard indexes are all significantly below one, the level of concern, even though conservative assumptions were used in the fate and transport modeling and exposure assumptions � ' ® TligGA97300BNAWOCKTONLREPORT%SHOREPM A%SNA 6-4