Probabilistic risk assessment of a contaminated site

The results of deterministic and probabilistic risk assessment at a contaminated site were compared. The deterministic point estimates of the incremental lifetime cancer risk following exposure to dioxin/furan and PCB contaminated recreational site were 1 x 10(-4) for dioxins/furans and 3 x 10(-5) for PCBs. The point estimates located at the 99,8 and 97,3 percentiles in the probabilistic range of risk. The distribution means were 4 x 10(-6) for dioxins/furans and 4 x 10(-6) for PCBs, respectively. The point estimates highly overestimated the risk, whereas, the probabilistic approach resulted valuable information regarding the possible distribution of risk. Clean-up levels corresponding risk level of 10(-6) were also calculated. The point estimates were 5,5 ng TCDD-equivalents/kg soil and 0,5 mg PCBs/kg soil. The 5(th) percentile values, which are protective for 95% of the population, were 11,6 ng TCDD-equivalents/kg soil and 0,4 mg PCBs/kg soil. The sensitivity analysis revealed that the soil concentration data is the dominating parameter when it comes to the uncertainty in this assessment.