How Safe is Alaska's Human Health Water Quality Standard for Dioxin, 1996 Environmental Conference Proceedings

Alaska’s ambient water quality standard (WQS) for potential human carcinogens currently are based on a cancer risk criterion of one in one hundred thousand (l0 -5 ) excess lifetime cancer risk. A concern had been raised that these standards may not sufficiently protect Alaskan residents, particularly those populations whose fish ingestion rates are significantly greater than residents of other states. To evaluate this concern, a probability analysis (also known as Monte Carlo analysis) was conducted to evaluate realistic risks to Alaskan fish-eating populations. Groups evaluated were rural inland populations, rural coastal populations, urban inland populations, urban coastal populations, and coastal sportfisherman. For each group, consumptions rates of various migratory and resident fish were evaluated For both inland and coastal locations, the areas of impact of wastewater discharges were included in the probability analysis. The Monte Carlo analysis demonstrated that the level of protection afforded by the current dioxin WQS is, in fact, higher than a l0 -5 risk level. The 95th percentile level of protection was closer to the 10 -7 level for even subsistence fish-eating populations. These results showed that more stringent water quality standards are not justified.