APPENDIX IV.I.1 Delivery Truck HRA
Diesel Particulate Matter (DPM) Health Risk Assessment (HRA) of Delivery Trucks from the Project at Pico and Sepulveda, Los Angeles, California Introduction This health risk assessment (HRA) evaluates the chronic cancer risk and non-cancer health effects of diesel particulate matter (DPM) associated with delivery trucks to the Project at Pico and Sepulveda. Methodology The methodologies and assumptions used in this HRA analysis are consistent with U.S. EPA, Cal/EPA, CARB, SCAQMD and the State s Office of Environmental Health Hazard Assessment (OEHHA) guidance. The primary guidance document used in this analysis is the SCAQMD s Health Risk Assessment Guidance for Analyzing Cancer Risks from Mobile Source Diesel Idling Emissions for CEQA Air Quality Analysis (SCAQMD 2003) and OEHHA s Air Toxics Hot Spots Program Risk Assessment Guidelines (OEHHA 2003). The basic components of a risk assessment as identified in the guidance are as follows: (1) hazard identification; (2) exposure assessment; (3) dose response assessment; and (4) risk characterization. Hazard Identification The hazard identification portion of the Project s DPM HRA involves identifying if a hazard exists, and if so, what are the pollutants of concern and their associated potential adverse health effects. In this HRA, the primary hazard from the Proposed Project is emissions from vehicular sources (specifically diesel-powered delivery trucks) associated with delivery trucks. Exposure Assessment The exposure assessment estimates the extent of exposure to vehicular exhaust for which potential cancer and chronic non-cancer effects will be evaluated. This assessment starts with a emission quantification, followed by dispersion modeling and an estimation of long-term exposure levels. The quantification of diesel exhaust emissions requires a diesel exhaust emission rate from diesel trucks and travel frequency. Emission rates for various truck classes are estimated based on emission factors obtained from the EMFAC2007 computer model. The daily number of truck trips for the Proposed Project is based on the truck trips at comparable major retail stores. Approximately eight heavy-duty trucks (HDT) are projected for the proposed major retail. The annual average diesel exhaust emissions have been used to evaluate the potential chronic (longterm) cancer and non-cancer health impacts at receptors surrounding the project site. As there is no acute toxicity factor for diesel exhaust, short-term diesel emissions were not forecasted.
With regard to travel within the project site, the delivery trucks would enter the project site from the west entrance and travel approximately 250 feet to the loading dock. The truck idling calculations were based on a total idling time of 15 minutes per truck. It is assumed that trucks would maintain a speed limit of approximately 10 miles per hour within the project site boundaries. Dose-Response The dose-response assessment is the process of characterizing the relationship between exposure to TAC exhaust and the incidence of an adverse health effect in exposed populations. The estimation of potential inhalation cancer risk posed by exposure to TACs requires a cancer potency factor. Cancer potency factors are expressed as the upper bound probability of developing cancer assuming continuous lifetime exposure to diesel exhaust at a dose of one milligram per kilogram of body weight, and are expressed in units of inverse dose as a potency slope (i.e., [mg/kg/day] -1 ). A cancer potency factor when multiplied by the dose of a carcinogen gives the associated lifetime cancer risk. The estimation of potential inhalation chronic and acute non-cancer effects posed by exposure to TACs requires a chronic and acute reference exposure levels (RELs). Chronic and acute RELs are concentration levels (that is expressed in units of micrograms per cubic meter (µg/m 3 ) for inhalation exposures), at or below which no adverse health effects are anticipated following exposure. Cancer potency factors and RELs were obtained from OEHHA s Toxicity Criteria Database (http://www.oehha.ca.gov/risk/chemicaldb/index.asp) Risk Characterization Risk characterization combines the maximum annual average TAC concentration from the exposure assessment and the cancer potency factor and REL from the dose-response analysis to estimate the potential inhalation cancer risk and chronic hazard index (HI) from the exposure to vehicle emissions. The equation below was used to estimate exposure through inhalation as a function of respiration rate and the concentration of TACs in air (OEHHA, 2003, Equation 5.4.1 A) with the recommended default values. Dose-inh = [Cair * {DBR} * A * EF * ED * 10-6 ] / AT where: Dose-inh = Dose through inhalation (mg/kg/day) Cair = Concentration of TAC in air (µg/m 3 ), see above {DBR} = Daily breathing rate (L/kg body weight - day)
A = Inhalation absorption factor EF = Exposure frequency (days/year) ED = Exposure duration (years) 10-6 = Micrograms to milligrams conversion, Liters to cubic meters conversion. AT = Averaging time period over which exposure is averaged, in days (e.g., 365 days for 70 yr for cancer risk) Exposure parameters for residents are described below: A daily breathing rate of (DBR) 271 L/kg day was assumed for adult residents and 452 L/kg day for child residents. The inhalation absorption factor (A) is assumed to be 1. That is, 100% of the chemical inhaled is assumed to be absorbed. This is a standard practice under current risk assessment guidelines. The exposure frequency (EF) was assumed to be 350 days per year. It was assumed the residents would be away from home two weeks per year. Residents were assumed to reside at the proposed project for exposure durations (ED) of nine years for children and 30 years for adults. As a conservative estimate, off-site residents were assumed to have an ED of 70 years. For carcinogenic effects, the averaging time (AT) was considered to be equivalent to a lifetime (70 years or 25,550 days). The daily breathing rates used in this HRA approximate the residential inhalation rate is consistent with the average residential inhalation rates provided in OEHHA (2003) guidance for 70-year duration point-estimate calculations. Upper-bound daily breathing rates are also provided in the OEHHA (2003) guidance; however, given the conservative exposure duration (70 years) and an inhalation absorption factor (100% absorption), the average inhalation rate was considered appropriate for this evaluation. The following equation was used to estimate the inhalation cancer risk based upon the calculated dosage. Inhalation Cancer Risk = (Dose-inh, mg/kg/day) x (Cancer Potency Value, [mg/kg/day] -1 ) The calculated cancer risk from on-site delivery truck DPM emissions is 2.5E-06 for adult residents and 5.3E-07 for child residents.
Non-Cancer HI The chronic HI is a calculated ratio. Exposures above the REL are indicated by an HI greater than one (1) and may indicate that the source has a potential to cause adverse non-cancer health effects. HI = (Cair, µg/m 3 ) / REL The chronic non-cancer HI associated with the Proposed Project is 0.0017. Conclusions The maximum cancer risks for the Proposed Project is 2.5E-06 or 2.5 in one million, which is below the significance criteria of 10 per one million. The chronic non-cancer HI is 0.0017, well below 1. An HI of less then 1 is considered to be less than significant. As such, the impacts associated with chronic non-cancer health effects are concluded to be less than significant. It should be noted that the estimated cancer risks and non-cancer hazard index presented in the HRA conducted for the Project is based on a number of assumptions, most of which are considered conservative. As a result of the effects of these conservative assumptions, the calculated risks are likely to overestimate actual risks. The following list summarizes some of these conservative estimates used in the HRA: Exposure Assumptions Health risks were calculated with the assumption that residents spend every hour of every day of exposure at that location for 70 years. However, few people will reside in the same location for their entire lifetime. Indeed, the U.S. EPA has estimated that 50% of the population lives in the same residence for only nine years, while only 10% remain in the same house for 30 years. Adults, moreover, spend only 68-73% of their total daily time at home, rather than the 100% assumed here. 1 Accordingly, the actual risks to residents are likely to be lower than those calculated in this assessment. Chemical Toxicity There are a number of uncertainties in conducting a toxicity assessment. The primary areas of uncertainty include the assumption that adverse effects observed in animal experiments would also be observed in humans (animal-to-human extrapolation), and that the toxic effects observed after exposure by one route would occur following exposure by a different route (route-to-route extrapolation). Calculation of Risk The U.S. EPA notes that the conservative assumptions used in a risk assessment are intended to assure that the estimated risks do not underestimate the actual risks posed by a site and that the estimated risks do not necessarily represent actual 1 U.S. EPA 1997.
risks experienced by populations at or near a site. 2 By using standardized conservative assumptions in a risk assessment, U.S. EPA further states that: These values [risk estimates] are upperbound estimates of excess cancer risk potentially arising from lifetime exposure to the chemical in question. A number of assumptions have been made in the derivation of these values, many of which are likely to overestimate exposure and toxicity. The actual incidence of cancer is likely to be lower than these estimates and may be zero. The estimated risks in the risk assessment for the Proposed Project are based primarily on a series of conservative assumptions related to predicted emission rates, concentrations, exposure, and chemical toxicity. The use of conservative assumptions tends to produce upper-bound estimates of risk and is likely to result in substantial overestimates of exposure, and hence, risk. In summary, both cancer risks and chronic non-cancer health effects associated with the delivery trucks of the Proposed Project would be less than significant. 2 U.S. EPA 1989.
I. REFERENCES California Air Resources Board (CARB). Almanac Emissions Projection Data 2006 Edition, website: http://www.arb.ca.gov/app/emsinv/emssumcat.php. 2006. Office of Environmental Health Hazard Assessment (OEHHA), 2003. The Air Toxics Hot spots Program Guidance for Preparation of Health Risk Assessments. August 2003. SCAQMD. Health Risk Assessment Guidance for Analyzing Cancer Risks from Mobile Source Diesel Idling Emissions for CEQA Air Quality Analysis. August 2003. United States Environmental Protection Agency (USEPA). 1997. Exposure Factors Handbook. National Center for Environmental Assessment. Office of Research and Development. Washington, D.C. USEPA. 1989. Risk Assessment Guidance for Superfund: Volume I - Human Health Evaluation Manual (Part A). Office of Emergency and Remedial Response. Washington, D.C.
DIESEL TRUCK EXHAUST EMISSIONS (PM10) Running Idle Idle Running Idle Trips PM10 Distance Exhaust Exhaust Idle Exhaust Hours Exhaust Exhaust Truck Per gm/mi On Site PM10 gm/min Time PM10 Operation PM10 PM10 Type Day1 (on site)2 (mi/trip) (gm/day) (on site)3 (min/trip)4 (gm/day) (hrs)5 g/s g/s HDT 8 0.811 0.1 0.6 0.0165 15 2.0 20.0 9.01111E-06 2.75278E-05 Total Project Site Emissions: 9.01111E-06 2.75278E-05 1 Source: Project proponent estimates based on proposed size of project 2 Source: EMFAC2007 emission factors for year 2013 at 10 miles per hour. 3 Source: EMFAC2007 emission factors for year 2013. Based on 0 mph running exhaust emission factors divided by 60 minutes per hour. 4 Assumes idling will be limited to 15 minutes per trip. 5 Hours of operation from 4 am to midnight.
Exposure Factors Variable Abbrev Value Unit Daily breathing rate- child DBR_c 452 L/kg-d Daily breathing rate- adult DBR_a 271 L/kg-d Inhalation absorption factor A 1 unitless Exposure frequency EF 350 days/years Exposure duration_child ED_c 9 years Exposure duration_adult ED_a 70 years Averaging time period AT 25,550 days Notes Emission factors obtained from OEHHA's The Air Toxics Hot spots Program Guidance for Preparation of Health Risk Assessments. August 2003.
Residential Cancer Risks Concentration Child Dose Adult Dose CPF Cancer Risk Cancer Risk Source Location x/q ER ug/m3 mg/kg-day mg/kg-day (mg/kg-d)-1 Child Adult On-site Delivery Point of Maximum Impact 236.26 3.65389E-05 8.6E-03 4.8E-07 2.2E-06 1.1 5.3E-07 2.5E-06 Truck Travel On-site Residents 88.53 3.65389E-05 3.2E-03 1.8E-07 8.4E-07 1.1 2.0E-07 9.2E-07