Question

Risk Assessment The residential drinking water in a small town with a population of 50,000 has been detected to contains 0.5 ppb tetrachloroethylene. There is also a waste incineration plant in the town that emits 0.001 ppb dioxin. Long-term health monitoring of the town yielded the following data: With Disease Without Disease Exposed 72 185 Not Exposed 34 560 1. What are the CDI values of the two contaminants? (5 points) 2. How many cancer cases will be caused by tetrachloroethylene and dioxin, respectively? (5 points) 3. What exposure assessment report can we generate? (5 points) 4. Calculate the overall risk that the residents are facing. (5 points)

answer also 3 and 4...

Answer 1

Given Population 50,000 Concentration of tetrachloroethylene ₂a = 0.5 ppb = 0.0005 mgle Concentration of dioxin = 0.001 ppb. CG HGO E 0.000001 ngll. 1) CDI values (Intake rate CDI Ga = Cx CRX EF ED BW X AT c = Concy of contaminant (mgle) CR= contout rate (llday = 2lld EF = Exposure frequency (days yr) ED= Exposure duration (yxs)=30 BW = Body weight (kg) = 70 AT= exposure period (days) = 365 CDI = 0.0005 x 2x 350 x 30 (CC) 70 x 365 = 4.1095*10-4 (ng /kg-day) | CDT : 00 00 00 x2x30x30 (Cutty 02 708365 =81219 x 10-7 img kg-day)

(2) Cancer cases Estimated reference close factors CRED ..) C cla = 5x10-4 (mg 1kg day) - 2) ₂ H₂O₂ = No data. Hazard quotient HQ= IDI RED .) 4.1095 x 10-4 = 0.8219 <1 5x io 4 acceptable risk 3) Risk = CDI X SF Sf = slope factor SF Gau = 0.046 SF dignin - 1.5810-5 Risk i au = 4.1095x10 " x 0.046 = 1.89 x105 > 10-6 4) wisk unacceptable. Risk dioxin = 8-219x107x 1.5*10.5 = |- 23x10-11 <10-6 h) disk acceptable