Question

6.28 Modified You are to determine if exposure by oral ingestion to the chemicals xylene, toluene, arsenic, and hexavalent chromium poses a noncarcinogenic health risk. The chemical-specific reference doses (mg/kg-day) obtained from IRIS are: xylene (0.2), toluene (0.8), arsenic (0.0003), and hexavalent chromium (0.003) Assume a 70 kg individual consumes 2 liters of water per day with these chemicals dissolved at a concentration of 1 mg/L. Determine the HQ for the water.

Answer 1

Given data: Chemical specific reference doses in mg/kg -day: Xylene 0.2 Toluene 0.8 Arsenic = 0.0003 Hexavalen chromium = 0.003 Individual person weight is 70 kg Calculate the reference dose of chemical consumed by the individual as follows: Dose (mg /kg - day) =Concentration x Individual consumption Individual Person weight Substitute 1 mg /L for concentration, 2 L/day for individual consumption, and 70 kg for individual person weight 1 mg/Lx2 L/day Dose 70 kg = 0.0286 0.03 mg/kg - day

Xylene reference dose: 0.2 > 0.03 Therefore, xylene does not possess a non- carcinogenic health risk. Risk is acceptable Toluene reference dose: 0.8 > 0.03 Therefore, toluene does not possess a non- carcinogenic health risk. Risk is acceptable. Arsenic reference dose: 0.0003 < 0.03 Therefore, Arsenic will possess a non- carcinogenic health risk. Risk is not acceptable Hexavalent chromium reference dose: 0.003 < 0.03 Therefore, Hexavalent chromium will possess a non- carcinogenic health risk. Risk is not acceptable

Calculate the Hazard quotient for the water as follows: Reference dose of chemical consumed by the individual Hazard quotient (HQ) Reference dose of chemical In this problem, Hazard quotient calculated for Arsenic and Hexavalent chromium. Because these chemicals possess health risk. For Arsenic: Substitute 0.03 mg/kg- day for reference dose of chemical consumed by the individual, and 0.0003 mg/kg - day reference dose of Arsenic 0.03 Hazard quotient (HQ)= 0.0003 = 100 For Hexavalent chromium: Substitute 0.03 mg/kg - day for reference dose of chemical consumed by the individual, and 0.0003 mg/kg - day reference dose of Hexavalent chromium 0.03 Hazard quotient (HQ) 0.003 = 10 Therefore, the HQ for Arsenic and Hexavalent chromium chemicals are 100 and 10 respectively