In the past two decades, Michigan’s dioxane standards have seen extremes, going from 3 to 85 parts per billion (ppb). Now 7.2 ppb is being proposed by the MDEQ. Other states' standards are all over the map. The EPA’s current recommended levels for dioxane exposure vary greatly as well, depending on multiple factors. In this installment of WEMU’s “The Green Room,” Barbara Lucas looks at some reasons why it is so hard to come up with uniform guidelines for safe levels of dioxane.