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5 <br /> <br />Exposure Assumptions for Residential Individual Cancer Risk <br />Age Group <br />Breathing <br />Rate <br />(L/kg-day)13 <br />Age <br />Sensitivity <br />Factor 14 <br />Exposure <br />Duration <br />(years) <br />Fraction of <br />Time at <br />Home15 <br />Exposure <br />Frequency <br />(days/year)16 <br />Exposure <br />Time <br />(hours/day) <br />3rd Trimester 361 10 0.25 1 350 24 <br />Infant (0 - 2) 1090 10 2 1 350 24 <br />Child (2 - 16) 572 3 14 1 350 24 <br />Adult (16 - 30) 261 1 14 0.73 350 24 <br />For the inhalation pathway, the procedure requires the incorporation of several discrete variates to <br />effectively quantify do se for each age group. Once determined, contaminant dose is multiplied by the <br />cancer potency factor (β€œCPF”) in units of inverse dose expressed in milligrams per kilogram per day <br />(mg/kg/day-1) to derive the cancer risk estimate. Therefore, to assess exposures, we utilized the <br />following dose algorithm: 𝐷𝐷𝑠𝑠𝐸𝐸𝑅𝑅𝐴𝐴𝐴𝐴𝐴𝐴,𝑝𝑝𝑝𝑝𝑝𝑝 π‘Žπ‘Žπ‘Žπ‘Žπ‘π‘ π‘Žπ‘Žπ‘π‘π‘”π‘”π‘”π‘”π‘π‘= πΆπΆπ‘Žπ‘Žπ‘Žπ‘Žπ‘π‘× πΈπΈπΈπΈ × οΏ½π΅π΅π‘…π‘…π΅π΅π΅π΅οΏ½ × π΄π΄ × πΆπΆπΈπΈ <br /> where: <br />DoseAIR = dose by inhalation (mg/kg/day), per age group <br />Cair = concentration of contaminant in air (ΞΌg/m3) <br />EF = exposure frequency (number of days/365 days) <br />BR/BW = daily breathing rate normalized to body weight (L/kg/day) <br />A = inhalation absorption factor (default = 1) <br />CF = conversion factor (1x10-6, ΞΌg to mg, L to m3) <br />To calculate the overall cancer risk, we used the following equation for each appropriate age group: 𝐢𝐢𝑅𝑅𝑠𝑠𝑠𝑠𝑅𝑅𝑔𝑔 𝑅𝑅𝐸𝐸𝐸𝐸𝑅𝑅𝐴𝐴𝐴𝐴𝐴𝐴= 𝐷𝐷𝑠𝑠𝐸𝐸𝑅𝑅𝐴𝐴𝐴𝐴𝐴𝐴 × πΆπΆπΆπΆπΈπΈ × π΄π΄π΄π΄πΈπΈ × πΈπΈπ΄π΄πΉπΉ × πΈπΈπ·π·π΄π΄π΄π΄ <br /> <br />13 β€œSupplemental Guidelines for Preparing Risk Assessments for the Air Toxics β€˜Hot Spots’ Information and <br />Assessment Act.” SCAQMD, October 2020, available at: http://www.aqmd.gov/docs/default-source/planning/risk- <br />assessment/ab-2588-supplemental-guidelines.pdf?sfvrsn=19, p. 19; see also β€œRisk Assessment Guidelines Guidance <br />Manual for Preparation of Health Risk Assessments.” OEHHA, February 2015, available at: <br />https://oehha.ca.gov/media/downloads/crnr/2015guidancemanual.pdf. <br />14 β€œRisk Assessment Guidelines Guidance Manual for Preparation of Health Risk Assessments.” OEHHA, February <br />2015, available at: https://oehha.ca.gov/media/downloads/crnr/2015guidancemanual.pdf, p. 8-5 Table 8.3. <br />15 β€œRisk Assessment Procedures.” SCAQMD, August 2017, available at: http://www.aqmd.gov/docs/default- <br />source/rule-book/Proposed-Rules/1401/riskassessmentprocedures_2017_080717.pdf, p. 7. <br />16 β€œRisk Assessment Guidelines Guidance Manual for Preparation of Health Risk Assessments.” OEHHA, February <br />2015, available at: https://oehha.ca.gov/media/downloads/crnr/2015guidancemanual.pdf, p. 5-24.