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.
David Fair (DF): How much of the chemical 1,4 dioxane would you be willing to drink? When Michigan’s new, stricter level is instituted, folks on well water here could still be drinking over 20 times more dioxane than in places like Tucson, Arizona. WEMU’s “The Green Room” continues its series on Ann Arbor’s contaminated groundwater with an exploration of the elusive question: “What is a safe level of 1,4 dioxane?”
Barbara Lucas (BL): Have you had it tested for Dioxane here?
Roger Rayle: Yes, long time ago.
BL: What was it?
BL: I’m with Roger Rayle: Tireless watchdog of Ann Arbor’s dioxane contamination, and leader of “Scio Citizens for Safe Water.” We’re next to the wellhead on his property, adjacent to Honey Creek. I ask him what level he considers safe for dioxane.
Rayle: There is no really safe level for this compound. You just have to pick what you think is an acceptable level.
BL: When it comes to dioxane levels, it’s the wild west out there. The EPA doesn’t regulate it, and most states haven’t set allowable levels. Rayle says Michigan’s level used to be low: 3 parts per billion.
Rayle: Then in ’94-‘95, the powers that be in Lansing under the Engler administration and the GOP legislature gutted the polluter pay law.
BL: He says they changed the odds acceptable for dying of cancer from one in a million, to one in a hundred thousand. So Michigan’s allowable dioxane level shot up—from 3 to 77 to 85 ppb. Then, new research came to light.
Rayle: Since 2010 the EPA has determined that dioxane is more dangerous than once thought, so the one in a hundred thousand over a 70-year lifetime should be 3.5 ppb.
BL: If the EPA recommends 3.5 for that span and those odds, why then is the Michigan DEQ proposing 7.2, over twice as high? Rayle says it’s due to the difference in span—the number of years used as the period of exposure. Instead of the EPA’s 70 years, in Michigan, it’s a 32-year span. So how did the Michigan legislature arrive at 32?
Rayle: It's a mystery. A made up number. Besides what contamination could possibly last longer than 32 years? Well, here's one!
BL: I catch up with Mitch Adelman of the Michigan Department of Environmental Quality. We discuss the grey areas involved in arriving at acceptable risk.
Adelman: Then you get into the question of ‘how clean is clean’? Or, ‘how dirty is clean,’ for those who don’t like the 7.2?
BL: We discuss how we routinely accept other, much greater risks in our lives. For instance, odds of dying in a motor vehicle incident are more like one in a hundred.
Adelman: I choose to ride a bike and take that risk. I choose to canoe and that could be a risky thing too. It is a lot worse than a one in a million risk. Whereas someone in Flint didn’t choose to drink lead-contaminated water. Or somebody in Ann Arbor, even if they are drinking one part per billion, and we say that is that’s an acceptable risk from a legal standpoint, that might be something that is unacceptable to their individual risk tolerance and they didn’t sign up for it!
BL: Then, there’s the unknown impact to future generations. Here’s toxicologist Dr. Rita Loch-Caruso, at the March 8th meeting of the Coalition for Action on Remediation of Dioxane.
Dr. Rita Caruso: I tried to find something and I couldn’t find a single reference on whether dioxane is in breast milk or not. There are no human studies on reproductive or developmental toxicity, there's nothing on pregnancy. There is one rat study on developmental toxicity.
BL: Some would point out dioxane hasn’t been studied much because its toxicity is relatively low. For others, like Roger Rayle, that’s not comforting.
Rayle: It's not in nature, it shouldn't be there. So zero is the safe level!
(BL): Barbara Lucas, 89 One, WEMU News.
(DF): “The Green Room” will continue its series on the 1, 4 dioxane groundwater contamination in the Ann Arbor-area in the weeks and months to come.