In the 1960s through 1980s, a medical filter manufacturer in Ann Arbor discharged 1,4-dioxane (an industrial solvent) directly into the environment, where it ultimately leached into underlying groundwater aquifers. A plume of 1,4-dioxane has been spreading under Ann Arbor and could pose water quality risks if it reaches Barton Pond, which supplies 85% of the city's drinking water. So, we can evaluate the given information by concluding that the EPA classifies 1,4-dioxane as a probable carcinogen with a potency factor of 0.011 (mg/kg/d)1. If the water contains the EPA's allowable limit of 7.2 μg/L of 1,4-dioxane, calculate the carcinogenic risk based on the default EPA exposure factors over a lifetime for ingestion of potable water in an average adult. Is the water safe to drink based on the "rule of thumb" discussed in class?
