A Poison in Small Doses

Thousands of wells in Bangladesh are contaminated with arsenic from groundwater aquifers. Oregon State University researchers are studying the health consequences of low-dose exposure in rural communities.


October 13, 2015

Molly Kile tests a Bangladeshi woman for lead poisoning. (Photo courtesy of Molly Kile)
Oregon State University researcher Molly Kile tests a Bangladeshi woman for lead poisoning. (Photo courtesy of Molly Kile)

By Nick Houtman

IN 1971, A COUNTRY WHERE rural people ride rickshaws to work and where millions live just above sea level jumped into global consciousness with help from a group of musicians. The Concert for Bangladesh featured the likes of George Harrison, Ravi Shankar, Bob Dylan and Ringo Starr and raised $12 million for the South Asian country beset by war, natural disaster and disease. But in the wake of the aid that poured into the densely populated and impoverished nation, a massive tragedy unfolded. The World Health Organization (WHO) called it the “the largest case of mass poisoning in the world.”

Public health officials discovered that thousands of wells installed to provide safe drinking water were contaminated with arsenic from groundwater aquifers. “If you put a hand pump in an area where you’ve said the water is unsafe and tell people it’s now safe, people will go there. You’ve just created infrastructure,” says Molly Kile, an environmental epidemiologist at Oregon State University.

“We know that arsenic levels in the hundreds of parts per billion are bad. No one argues about that,” says Kile, an assistant professor in the College of Public Health and Human Sciences. “But what about 5 or 15 or 20 parts per billion? Understanding the health consequences of low-dose exposure is an emphasis of our work.”

Arsenic is a well-known poison with a colorful history. The Medicis of Renaissance Florence were famous for feeding it to their enemies. In the 1800s, it was used in medicine, agricultural chemicals and rat poison. Dr. Campbell’s Safe Arsenic Complexion Wafers promised smooth, velvety skin “to all women who desire beauty.” Paris green, a lustrous pigment containing arsenic, was used in paint, wallpaper, clothing and even children’s toys.

In drinking water, it takes very little arsenic to cause trouble. Concentrations of hundreds of parts per billion (an amount equivalent to a few minutes in 32 years) can lead to skin lesions and bladder and skin cancer.

Since 2002, Kile and her partners — students and physicians at the Dhaka Community Hospital and the Harvard T.H. Chan School of Public Health — have turned Bangladesh into a laboratory for arsenic toxicology. With the help of people in rural communities, what they are learning could do more than address a crisis in South Asia. A 2007 study estimated that about 137 million people worldwide are exposed to water that exceeds the WHO’s arsenic limit of 10 parts per billion.

Arsenic in Rural Oregon

As a graduate student in Water Resources Science at Oregon State, Lauren Smitherman looked for patterns of arsenic contamination in groundwater. Read more…

Arsenic-containing minerals are common in the bedrock of North America. In Oregon, testing by the Oregon Health Authority and county health departments has found well water with arsenic concentrations over that standard in communities such as Tualatin, Sweet Home and Ontario.

Out of Place

Kile began her research as a doctoral student at Harvard looking at dietary sources of arsenic and biomarkers of exposure and disease in rural Bangladesh. “I was visiting places that had never seen Westerners,” she says. “Here I was, an unmarried woman traveling without a husband or father, asking personal questions. And I’m 6 feet tall. I’m big. When I walk through a village, people notice,” she laughs. “I can empty a school in seconds when the kids crowd around to look at me.
“And yet,” she adds, “they are the warmest, most hospitable, welcoming people. In the beginning, the whole situation was totally foreign to my Western eyes. But I loved it and wanted to understand their point of view.”

Kile had important allies. Through her Ph.D. adviser David Christiani at Harvard and Quazi Quamruzzaman, the visionary founder of the Dhaka Community Hospital, she was paired with Bangladeshi partners who have become steadfast colleagues in her research. During her annual trips, she lived with a family with whom Kile had a personal connection through art: Her grandmother and the family’s father were both artists.

Community members who valued health care and understood the importance of reducing arsenic exposure helped Kile and her research partners recruit subjects. “We were welcomed everywhere we went,” she explains. “We were never chased out of town or harassed. There’s always been a lot of respect,” which she attributes to the Dhaka Community Hospital’s approach to community partnerships. “We couldn’t do what we do without them,” she adds.

In rural villages, Kile and her team collect tissue samples (toenails, hair and urine are reliable indicators of arsenic concentrations in the body). They monitor people with arsenic-induced skin lesions, interview pregnant women and track the health of children.

Arsenic and Disease

What they are finding is generating a new view of the venerable poison. For example, in the journal Environmental Health, they reported that higher arsenic concentrations in women were associated with more frequent vomiting, diarrhea and abdominal cramping during pregnancy.

The researchers are investigating the possibility that arsenic may compromise the immune system in utero, leading to a lifetime of increased risk for infectious disease. They are also studying whether arsenic exposure may also make vaccinations less effective.

In a separate study using data collected by the Centers for Disease Control and Prevention in the United States, Kile and Ellen Smit, an Oregon State colleague, have already shown that higher levels of arsenic in urine correlate with a reduction in antibodies to the varicella virus. Varicella causes chickenpox in children and shingles in adults. “We interpret that as increasing risk for shingles. While we don’t know how it actually causes infection, we do know that arsenic modulates the immune system,” says Kile.

In Bangladesh, Kile and her team, including Oregon State Ph.D. student Andres Cardenas, are collecting data on the health of children to look for relationships between arsenic and the frequency of illnesses from colds to diarrhea. “Our hypothesis,” says Kile, “is that respiratory and other illnesses in the first five years of life are correlated with the mom’s arsenic exposure. We are focusing on this early exposure period because the immune system begins to be programmed in utero, and this might be a particularly vulnerable time.”

If that turns out to be true, public health policies may need to be revised. “We need to be removing the exposure from mom’s world as adults, which means creating policies and interventions that protect women of reproductive age from harmful exposures,” she says. “But that does not have the same policy traction. Somehow we’re bad at that. We put efforts into protecting babies, but what if the toxic exposure has already happened (prenatally)? This puts more emphasis on protecting the entire population, looking at drinking water, dietary exposure and other types of pollution.”

Despite these gains in knowledge, the origins of the crisis in Bangladesh haunt Kile and her colleagues. “This was totally preventable,” she says. “People just didn’t look at the whole picture when these wells were being installed. We can’t let this happen again.”

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