Human Health Risk Assessment - Raytheon

More documents

Recommendations

Info

52 Human Health Risk Assessment DRAFT Index has been calculated because there are no non-cancer toxicity reference values available for 1,4-dioxane. 6.1.11 Apartment/Condo Residents Because a clean water layer prevents potential volatilization of COPCs from underlying groundwater, no potential exposure pathways are complete for residents of the Brandywine Apartments and Stone’s Throw Condominium Complex. The only COPCs detected in shallow groundwater in this area are benzene and 1,4-dioxane; however, volatilization from groundwater is not considered to be a complete exposure pathway for 1,4-dioxane and benzene was detected in only one shallow monitoring well (SMW-4) that, in prior sampling events, contained no benzene. Screening calculations indicate that, even if this concentration is not an artifact, potential risks from exposure to benzene in indoor and outdoor air are negligible. 6.1.12 Off-Site Residents (other than Brandywine and Stone’s Throw) Because a clean water layer prevents potential volatilization of COPCs from underlying groundwater, no potential indoor and outdoor air exposure pathways are complete for offsite residents. Potential risks from exposure to COPCs in irrigation water to off-Site residents are summarized in Section 6.2. As previously indicated, potential risks from exposure to COPCs in irrigation water are treated differently, using an RBSL approach, so that potential risks can be evaluated separately based on individual irrigation well sampling results. 6.2 Comparison to RBSLs A risk-based screening level approach is used to evaluate potential risks from exposure to COPCs in irrigation water because sampling of the irrigation wells is an ongoing process. As previously described, RBSLs are COPC concentrations that are intended to represent reasonable maximum exposure (RME) conditions and be protective of human health and/or the environment. COPC concentrations that fall below the RBSL are considered not to pose a threat to human health. If the concentration of COPC detected in an irrigation well exceeds the RBSL, then further characterization of the potential exposure is warranted. As indicated in Table 11 of the SARA, the only Site-related COPCs detected above GCTLs thus far in off-Site irrigation wells are 1,4-dioxane, TCE and cis-1,2-DCE at maximum concentrations of 32, 65 and 77 µg/L, respectively. The RBSLs calculated to protect against potential exposures to these three COPCs from ingestion of irrigation water are summarized below. As a matter of reference, a complete list of RBSLs for all COPCs is provided in Table 9.
53 Human Health Risk Assessment DRAFT Calculated RBSLs (µg/L) for Potential Exposures to 1,4-Dioxane, TCE and cis-1,2- DCE in Irrigation Water Exposure RBSL (µg/L) Pathway 1,4-Dioxane TCE cis-1,2-DCE Ingestion of Irrigation Water 670 670 10,200 Dermal Contact while Gardening 29,900 650 31,300 Inhalation during Lawn Irrigation 14,400 3,200 29,000 Ingestion of Homegrown Produce 522 205 29,500 Dermal Contact (Wading Pool Scenario) 2,320 416 6,360 Dermal Contact (Sprinkler Scenario) 2110 410 9,860 Ingestion of Irrigation Water. For the purpose of evaluating potential exposures to COPCs from ingestion of irrigation water, it is assumed that a resident drinks on average 0.12 liters per day (equivalent to 4 ounces per day), two days per month (24 days per year) for 30 years. This scenario is intended to evaluate potential exposures to individuals who may be involved in gardening or landscaping and take a drink from the garden hose. As indicated above, maximum concentrations detected in residential irrigation wells to-date indicate that an occasional sip from the irrigation well does not pose a health threat from COPCs. Dermal Contact while Gardening. Potential dermal exposure to COPCs may occur for residents using irrigation water during home gardening activities. Under this scenario, it is assumed that a resident is exposed to irrigation water on average for 1 hours per day, 1 day per week (50 days per year) for 30 years. During this hour, it is assumed that the resident’s head, hands, feet, forearms and lower legs could be exposed to irrigation water. The calculated RBSLs for 1,4-dioxane, TCE and cis-1,2-DCE are 29900, 650 and 31300 µg/L, respectively, which are well above maximum concentrations detected to date in residential irrigation wells. Inhalation of COPCs during Lawn Irrigation. The lawn irrigation scenario assumes that the resident is standing downwind during lawn irrigation for one hour per day, 50 days per year, for 30 years. As shown in the table above, calculated RBSLs to protect against potential exposures to COPCs from inhalation during lawn irrigation are well above maximum concentrations detected in residential wells. Ingestion of Homegrown Produce. Under this scenario we have assumed that a resident ingests 237 grams per day (about ½ pound per day; 183 pounds per year) for 30 years. These estimates were obtained from USEPA’s Exposure Factors Handbook and are based on a 7-day USDA survey of consumers of homegrown produce living in the South (USEPA, 1997). Maximum concentrations detected in residential irrigation wells to-date are all below RBSLs that have been calculated based on the plant uptake model presented by Ryan et al. (1988).
Page 1 and 2:
DRAFT Human Health Risk Assessment
Page 3 and 4:
ii Human Health Risk Assessment DRA
Page 5 and 6: Executive Summary 1 Human Health Ri
Page 7 and 8: 3 Human Health Risk Assessment DRAF
Page 11 and 12: 2 Conceptual Site Model 7 Human Hea
Page 15 and 16: 11 Human Health Risk Assessment DRA
Page 19 and 20: 3.2.3 Ambient Air Sampling 15 Human
Page 21 and 22: • Inhalation of Outdoor Air On-Si
Page 27 and 28: u = Wind speed (m/s) 23 Human Healt
Page 33 and 34: EPCa = Exposure point concentration
Page 35 and 36: where: DAD = Dermal absorbed dose (
Page 37 and 38: 33 Human Health Risk Assessment san
Page 41 and 42: non-carcinogenic effects (µg/L) Ri
Page 45 and 46: 5 Toxicity Assessment 41 Human Heal
Page 53 and 54: Potential Risks to On-Site Construc
Page 55: 51 Human Health Risk Assessment vol
Page 59 and 60: 7 Uncertainty Analysis 55 Human Hea
Page 63 and 64: Human Health Risk Assessment 1.0 su
Page 69 and 70: DRAFT Table 1. Constituents of Pote
Page 71 and 72: DRAFT Table 3. Comparison Between I
Page 73 and 74: DRAFT Table 5. Estimated Exposure P
Page 75 and 76: DRAFT Table 6. Summary of Exposure
Page 77 and 78: DRAFT Table 8. Source and Derivatio
Page 79 and 80: Human Health Risk Assessment DRAFT
Page 81 and 82: DRAFT Primary Primary Secondary Sec
Page 83 and 84: DRAFT Table A-1. Dose and Risk Calc
Page 89 and 90: DRAFT CSFd RfDd DA event C w DAD LA
Page 93 and 94: DRAFT CSFd RfDd DA event C w DAD LA
Page 95: DRAFT Table A-13. Dose and Risk Cal
show all

Human Health Risk Assessment - Raytheon

Create successful ePaper yourself

Delete template?

Save as template?