For a while last month, whenever Scott Elfenbein ’11 was thirsty he’d take a pull or two from a Nalgene bottle.
The rigid and nearly unbreakable containers are as common as flip-flops on campuses — and are widely used in American offices, in gyms, and on hiking trails as a lightweight alternative to metal and glass.
But Elfenbein was quaffing from Nalgene for science, not for convenience. He was one of about 80 Harvard College students who volunteered for a two-week April study intended to track levels of bisphenol A in their bodies.
The controversial chemical, known as BPA, is an endocrine disruptor and has been linked to reproduction and development problems, as well as breast cancer, in laboratory rats. Plastics with the number “7” in the recycling symbol (or the letters “PC”) contain the chemical.
Exposure of humans is widespread, federal health authorities say — 99 percent of the time through diet, by way of food and beverage containers. According to the federal Centers for Disease Control and Prevention (CDC), 96 percent of Americans over age 6 have traces of BPA in their urine.
“I’m sure you’ve heard about concerns with plastic bottles. Everybody has,” said lead researcher Karin Michels, a veteran epidemiologist who teaches and does research at Harvard Medical School, the Harvard School of Public Health, at Harvard-affiliated Brigham and Women’s Hospital (BWH), and at Harvard College.
“The thing is, nobody has done a study in humans, looking at whether drinking from Nalgene bottles really makes an appreciable difference in your BPA levels,” she said. “It’s astonishing.”
A few human studies have been done on associations between bisphenol A and human reproductive disorders, DNA damage, and even obesity. But they were too small and too few to prove the chemical’s reproductive toxicity, according to federal authorities.
Michels worked with eight students from her fall freshman seminar on nutrition, “You Are What You Eat,” to design, organize, and fund a small-scale study. (Five of the eight continued work on the study this spring.)
A competitive $15,000 grant from the Harvard University Center for the Environment supplied the money. It went for bottles (two plastic and two stainless steel for each subject), stipends ($25 per student), and lab assays ($10,000).
The study was vetted and approved by the Institutional Review Board at both Harvard College and BWH, where Michels co-directs the Obstetrics and Gynecology Epidemiology Center. Students had to sign informed consent forms, she said, and were educated about any risks beyond the risks that modern life, with its abundance of plastics, already offers.
Additional risks from drinking from Nalgene bottles for one week are minimal or absent, said Michels, because exposure to BPA is already so widespread.
“Given baseline exposure from other sources,” she asked, “do these bottles make a difference?” That was the question the study set out to determine.
For one week, the students drank only from stainless steel containers — a “clean-out phase,” Michels said. Virtually all Americans have traces of BPA in their urine, so a “cleaning-out phase” was necessary, she said.
Drinking from stainless steel did the job, making the 80 students — in effect — their own control group. (Biostatisticians call such a study arrangement a “crossover.”)
To Elfenbein, the steel phase of the study had a nonscientific advantage.
“The great thing about the steel is that it doesn’t absorb taste and smell, like plastic generally does,” said the Wigglesworth Hall resident, a native of Miami. “I can put coffee in it, and the next day my water doesn’t taste like coffee.”
After donating two urine samples, the same students started a week of drinking beverages only from Nalgene bottles. Then they submitted two more urine samples.
All of the samples were labeled and frozen, and are ready for shipment to a CDC assay laboratory — one that is world-famous, Michels said, for measuring levels of endocrine disruptors in urine.
Results will be ready in the fall, she said, and will show how much just one week of using Nalgene containers elevated levels of BPA. (Her students plan to write and submit a scientific paper under her guidance.)
BPA is used to make polycarbonate plastics, which are found in a wide range of consumer products, from compact discs and iPods to items that come in contact with food: sippy cups for toddlers, baby bottles, food containers, and the epoxy resin used to line most cans.
In polycarbonate sports bottles, the hotter and more acid a beverage is, said Michels, the more BPA leaches into it. (Nalgene containers are commonly only used for cold beverages, she said. But they are commonly cleaned in dishwashers with hot water and harsh detergents, which makes them release higher amounts of BPA.)
BPA has increasingly been linked to growing health concerns. Low doses of the chemical can cause chromosomal abnormalities in some rats, along with lowered sperm counts, urinary tract problems, and precancerous tumors. That’s according to a draft report released in April by the U.S. National Institute of Environmental Health Sciences.
The effects on humans are not positively known, the agency report said, acknowledging the scarcity of human data from just a few studies. But “the possibility that bisphenol A may alter human development,” it said, “cannot be dismissed.”
In humans, the report said, the chief possible concerns are neural and behavioral effects on fetuses, infants, and children. In older humans, the concerns are possible effects on the mammary and prostate glands, and the acceleration of puberty in females.
In April, Canadian health authorities started a two-year review process that may lead to restrictions on BPA, or even a ban. (Six years ago, the European Food Safety Authority imposed limits on exposure to BPA, based on body weight.)
And Nalgene Outdoor Products — without admitting risk — announced April 18 that it would phase out production of polycarbonate containers that contain BPA
Taking part in the study “has made me more aware of the controversy over Nalgene bottles,” said Elfenbein, who often still carries his stainless steel 27-ounce Klean Kanteen around with him.
But he poked fun at the study’s low risk. “I’m just a rat,” he said.
Study participant Henry T. Luu ’11, a Matthews Hall resident, will use his stainless steel container more too — but he finds it hard to give up plastic all together.
“A lot of what we do involves plastic, and it’s hard to get away from it,” said the Alhambra, Calif., native, who is a Gates Millennium Scholar.
Luu helped organize the spring phase of the study, and was one the eight students last fall who helped design the study and apply for funding.
“It’s given me something to think about,” he said of drinking from BPA containers.
“The data is not there yet,” said Luu, already sounding like a medical researcher. “But it’s enough to be concerned.”