Toxic Chemical Water Pollutant. Students in Tom Zoeller’s undergraduate endocrinology lab at the University of Massachusetts sat shoulder to shoulder in a glassy cube of a room, scrutinizing an equation they plugged into a spreadsheet only to have it spew out an unexpected stream of negative numbers.
These students aren’t in the professional world yet, but they, along with private and government researchers, are studying how perchlorate affects human health, with sometimes surprising results. The toxic component of rocket fuel and explosive munitions has polluted water supplies in 22 states, including Maryland.
Perchlorate was found this year in Aberdeen’s drinking water, and the Army acknowledges that military training exercises caused the contamination.
Though levels in Aberdeen are lower than those found in other parts of the country, the concerns are acute.
Perchlorate is known to interfere with thyroid function the question is when, how seriously and who is most susceptible. The students’ experiment is designed to measure changes in behavior and thyroid hormone levels in rat pups exposed to the chemical.
Early results from their experiment suggest that perchlorate could influence several events in the developing brain, including naturally occurring cell death, gene expression and cell migration.
But the work is preliminary, said Zoeller, a nationally known endocrine expert.
“We need to really look carefully at these data to make sure we haven’t committed errors and to repeat those observations before we would be comfortable about their significance,” he said.
The research is important because the Environmental Protection Agency has no standard for how much perchlorate people can ingest safely, leaving regulators and the military, whose weapons are the source of most perchlorate contamination, to battle over what that standard might be.
“This is high-stakes science,” said Annie Jarabek, leader of EPA’s perchlorate risk assessment team.
Chemical, People Can Be Exposed To
The agency is moving to complete a reference dose an estimate of the amount of a chemical people can be exposed to daily without damaging their health – for perchlorate by February, she said, which would be the basis for setting the national standard. Still, the agency is years away from that.
For the Defense Department, which will have to pay to clean up contaminated sites, deriving a standard has multibillion-dollar implications. It has anted up more than $30 million to research perchlorate and cleanup technologies.
“We know enough about perchlorate to be wary,” said Cal Baier-Anderson, toxicologist and technical adviser to a community group that monitors pollution issues at Aberdeen Proving Ground.
“We’ve got concerns about a chemical in the drinking water. Let’s get it out until we understand more about it.”
Zoeller got the idea to involve his students after he served on an EPA research review board this year. Some of the existing studies on perchlorate puzzled him.
“Most of the work on perchlorate suffers from the problem of having to be done quickly,” he said.
He ticked off a couple of examples: a Nevada study that compared infants based on the town they were born in, instead of the towns they lived in; and an EPA study that measured hormone levels and the size of specific brain regions though the two have no known correlation.
“If you look at the science, there are steps they could have taken, and probably should have taken, but they didn’t seem to get done over and over,” Zoeller said.
Some of the disagreements he had with methodology seemed so basic, he said, that “even my students in class could figure this out, and they did.”
But his plan was not to thumb his nose at researchers by having students poke holes in their work.
“I’m more concerned about the impact on students than on the national debate,” he said.
“The goal wasn’t to do a perfect experiment,” Zoeller said. “It was for students to get into the literature and start asking questions.”
They are the same kinds of questions that professional researchers are trying to answer.
Perchlorate has a very specific destination when it enters the body: the thyroid gland, which produces two hormones, T(3) and T(4), whose critical development roles include controlling metabolism.
The thyroid needs iodine to produce the hormones, but when perchlorate is present in sufficient amounts, it in effect bounces iodine out of its place in the production line.
In a healthy adult, perchlorate can be better tolerated because the thyroid stores up to a six months’ supply of hormones.
But newborns’ thyroids store less than a day’s worth of hormone and their brains are undergoing critical development processes from the start.
“They can’t afford to have anything interfere with their gland function,” Zoeller said.
Lab animal studies play a large part in trying to assess perchlorate’s effects on human fetuses and newborns. Zoeller’s students used rat pups in their study and modeled their work on a recent EPA study.
On Dec. 10, the afternoon before their research deadline, many questions about the data remained as students filtered in and out of the lab, as they have all semester. This is not the typical undergraduate lab, where you come in for a couple of hours, perform an experiment that reinforces the lecture, then leave. The research dictates the schedule, which may be an hour here and there, or a full day.
“It’s been hard on them that way, but they’ve really risen to the occasion,” said Eric Iannacone, a doctoral candidate in neuroendocrinology and Zoeller’s teaching assistant.
Jared Rice is analyzing film, using a computer program and digital camera, that measures messenger RNA in the brain. Foad Rasekh is assessing apoptosis, or normal cell death, under the microscope. Patricia Squitiero is analyzing data measuring hormone levels.
David Sharlin, a doctoral candidate who helps the undergrads from time to time, said the perchlorate lab is unusual for undergraduates in its independence and focus on a timely topic.
“You’re talking about people’s lives – the effects that will stick with a child for a lifetime,” he said. “You don’t know the effects. It’s scary.”
Rasekh and Rice said that learning practical research skills is what they like best about the lab.
“It’s really applying what you learn,” Rasekh said.
They’ve also seen how science works in the lab, Zoeller said, and that was the whole point. In preparing their reports, several students who have told Zoeller they would like to return next semester to continue their research have definite ideas of what they would do to improve their methods next time.
“These students now have a very clear understanding of the way these experiments have to be performed,” he said, adding that his “experiment” to give students ownership of their research and proceed with it has also been a success.
When Zoeller proposed the lab to his department chairman, Christopher Woodcock, he wasn’t sure what would happen. The $35 lab fee from each of the 16 students was nowhere near enough to cover a bill closer to $3,000.
But Woodcock said that after some thought, he decided, “This is great. It matches exactly with our learning goals.”
“I think it’s really crucial that we become involved with the debate and the students become involved in the debate,” he said, adding that he sees the university’s role as one of not taking sides, but of getting the right information and understanding it.
“Coherent public policy, that is the critical thing,” he said.