What We Know (And Still Don't Know) About The Chemical From Dartmouth's Waste Site

Nov 3, 2016

As residents of a Hanover, New Hampshire neighborhood grapple with a contamination caused by Dartmouth College, the school is providing more information about the health hazards of the chemical released.

The chemical 1,4-dioxane has been found on several properties and in at least two households’ drinking water. But what is 1,4-dioxane?

Here's what we know about the chemical and what remains unknown:

WE KNOW: It is a probable human carcinogen.

It is identified as a probable carcinogen for humans. In lab tests it is shown to be a definite carcinogen for animals.

At a recent health advisory meeting on the Dartmouth campus, Dr. Robert McLellan a Dartmouth-Hitchcock doctor and professor at Geisel Medical School told the crowd: “It is a definite animal carcinogen and has caused cancer in liver, kidney and nose, that's what makes it a probable but not a definite human carcinogen.”

With chemicals like 1,4 -dioxane it is almost impossible to assess definitive risk to humans because studies require long-term exposure. But McLellan thinks the risk of getting cancer from the chemical is actually pretty low.

According to the EPA, here are the odds: “An exposure at about 0.35 micrograms per liter drinking two liters of water a day for 70 years, exposed that whole length of time will have one excess cancer in 1 million people.”

WE KNOW: 1,4-dioxane is a commonly used ingredient in household items (although that may be changing.)

The 1,4-dioxane in the groundwater of the Hanover neighborhood stems from a hazardous waste site for radioactive research, but McLellan says 1,4-dioxane can be found in all sorts of household products:

“A variety of personal care products, hair and household products, some food containers, wrapping, pharmaceuticals, various adhesives, paint strippers, grease, plastics like PVC,” he explains. “So, 1,4-dioxane has actually been in our environment in a general way in many of these products that you use.”

McClellan says the FDA has made efforts to limit 1,4-dioxane use in the past several years. But federal research shows it is likely that around 12-percent of households around the country have 1,4-dioxane present in the water.

Rennie Farm, seen here in August 2016, is presumed to be the source of the Dartmouth contamination.
Credit Rebecca Sananes / VPR

WE KNOW: The Dartmouth 1,4-dioxane comes from something called scintillation fluid — something a lot of universities have to deal with.

Thomas Mohr a hydrologist and water contamination expert literally wrote the book on 1,4-dioxane, Environmental Investigation and Remediation: 1,4-Dioxane and other Solvent Stabilizers. He says because the chemical was used in research it shows up a lot in ground water near universities:

“A lot of life science laboratories used 1,4-dioxane in various ways," Mohr explains. "So some of their waste streams, while the volume is metrically, small did include 1,4 dioxane. So unfortunately a lot of research universities most often also have 1,4-dioxane contamination.”

Cornell University, the University of Arizona and the University of California, Davis are just a few other research universities which have recent issues with the contaminant.

At Dartmouth, the 1,4-dioxane was used in scintillation fluid, a solvent that helped track radiological movement through lab animals bodies during the 1960s and 1970s.

1,4-dioxane is no longer used in that way.

WE KNOW: Different jurisdictions regulate 1,4-dioxane differently, at different levels (and those levels are changing.)

Mohr says in 2012 the EPA lowered its guidance threshold for water used for drinking in response to animal tests.

“For drinking water, the EPA health advisory level is .35 parts per billion and that has caused a number of states to change their also advisory action levels for 1,4-dioxane,” he said.

In New Hampshire, where the Dartmouth contamination is affecting people, the threshold is much higher — 3.0 parts per billion. In neighboring Massachusetts, that level was lowered to 0.3 parts per billion.

BUT: There is much scientists still don’t know.

There are almost no studies on the effects of 1,4-dioxane and fertility according to the New Hampshire Department of Environmental Services.

What Mohr says what we don't know about 1,4-dioxane is how it might react with other chemicals people are exposed to in our environment.

“1,4-dioxane is what is called a tumor promoter; it can help a tumor to grow but it doesn't necessarily initiate a tumor,” Mohr says. “So if you have another chemical that initiates tumors and another that promotes it, the combination of those two can cause more problems than one chemical by itself.”

“We don't really understand the interaction of the chemicals in our bodies," Mohr adds. "So the philosophical and policy question that comes up is how do we manage the uncertainty and unknowns in chemical contamination in drinking water?”

Now, Dartmouth is addressing those uncertainties and responding to a potential lawsuit over the plume. The school has until early 2017 to respond to the demands of a family whose water was found to be contaminated with 1,4-dioxane last year.