Hanover
For more than hour in the campus’ Moore Hall, Robert McLellan, chief of the occupational and environmental medicine section at Dartmouth-Hitchcock Medical Center, outlined the medical science behind calculating the risks for neighbors of the Rennie Farm, the wooded hill near Lyme where the school buried several tons of test animals in the 1960s and ’70s.
A concept McLellan often returned to during his lecture was dosage. The critical difference between a toxic chemical and an innocuous one, he said, was the amount that a person is exposed to.
Or as the father of toxicology, the 16th-century scientist Paracelsus, put it, “The dose makes the poison.”
“It all matters on the dose,” McLellan told the crowd. “That’s what matters. The dose.”
The DHMC doctor went on to outline the existing research on the chemical found at Rennie Farm, a common industrial solvent component known as 1,4-dioxane.
The substance is used as a stabilizer in solvents and even in some household products, although, as McLellan noted, its prevalence in the home has decreased thanks to regulation. Dartmouth officials believe the 1,4-dioxane from Rennie Farm came from scintillation fluid, which helps scientists make measurements in experiments with radioactive components.
The compound is labeled a probable human carcinogen, and it is believed long-term exposure can cause kidney and liver damage. Short-term health effects include eye, nose and throat irritation, according to the Environmental Protection Agency.
McLellan said extensive medical research on 1,4-dioxane had been done using animals, but relatively little using humans. This is why, for instance, the EPA calls the chemical a “probable” human carcinogen: it is extrapolating animal symptoms from 1,4-dioxane onto humans.
“So what is your risk, then, of illness related to 1,4-dioxane?” he asked rhetorically at one point in the presentation. “Based on what we have measured in the wells in the area, now … there is negligible to no risk of toxicity associated with 1,4-dioxane.”
McLellan emphasized the word “toxicity” as he spoke that last sentence. Doctors consider most chemicals to have a safe threshold for consumption, he said, but carcinogens carry some risk at any level of exposure.
Lastly, McLellan brought up another concern, one that he called “very real”: psychological pressure.
“These kinds of events in the community cause this, and it’s not pleasant,” he said.
“I hope that some of that will help you with some of the stress and worry about the health issues associated with this chemical,” he added later.
“I feel so much better,” a woman in the audience whispered, laughing.
To end the talk, McLellan answered pre-submitted questions from residents.
Dartmouth currently is conducting a health survey that includes people who used to live in the area, and one submission asked what obstacles stood in the way of such a study.
McLellan brought up several issues, including the low population of the area, but also noted that cancer can be caused by many other risk factors. The average person has a nearly 40 percent risk of developing a form of it, he said.
“Most everyone has some exposure to consumer products containing 1,4-dioxane and thousands of other chemicals,” a slide in his presentation said.
He also told residents that the likelihood of kidney, nose and liver injury by toxic contamination from the Rennie Farm was “very remote,” based on the concentrations appearing in the environment.
The first family known to have been exposed to 1,4-dioxane, the Higginses of Rennie Road, have reported acute health effects, however. Shortly before their well tested positive for the substance at levels twice the state standard for water quality, the Higginses said they experienced dizziness, skin peeling in their mouths and sores on their skin.
Those symptoms went away when they stopped using their well water, they said.
The family last month notified Dartmouth of their intention to file suit under a federal law that allows private entities to bring polluters to court. Under the law, the college has 90 days to comply with the Higginses’ request for a more thorough cleanup, after which period the case can proceed in U.S. District Court in Concord.
After the talk, residents in attendance had a chance to ask questions, and one woman asked whether McLellan could explain the dermatological symptoms that the Higginses had faced. McLellan replied that he couldn’t address specific individuals’ health problems.
For further questions, officials told residents to attend drop-in hours at the college’s environmental health and safety office, located off Rope Ferry Road in the northern part of campus. The next such event is scheduled for 3 p.m. to 5 p.m. on Nov. 17.
Rob Wolfe can be reached at rwolfe@vnews.com or 603-727-3242.