Contents - Winter 2008
Vol. 1 No. 1
The Light at the Bottom of the Well
By Michael Robin
Graham George and Ingrid Pickering are using one of the world’s most powerful sources of light—a synchrotron—to help find out why the well water in Bangladesh is making millions of people sick.
In the summer of 2007, the husband and wife team—both Canada Research Chairs at the University of Saskatchewan— used the Stanford Synchrotron Radiation Laboratory in California to examine samples of blood collected from people in Bangladesh. They were looking for an unusual molecule they discovered in their previous research that may be the key to the mystery.
“Our initial results are extremely promising,” George says. “We’re certain we’re on the right track.”
An estimated 80 million Bangladeshis suffer from arsenicosis—a slow poisoning that mottles their skin, weakens their bodies, numbs their sensations and eventually kills them with cancer. The arsenic responsible is unavoidable—it occurs naturally in the wells the people rely upon for all their drinking and cooking needs.
Several years ago, George and Pickering discovered the quirky molecule they are now searching for in the blood samples. They were trying to solve another long-standing puzzle in toxicology: both arsenic and selenium ingested in large enough doses are lethal, but if you combine the two doses and ingest them at the same time, you’ll do just fine.
What could be going on?
To find out, Pickering and George collaborated with University of Calgary toxicologist Juergen ailer to conduct experiments at the Stanford synchrotron. Their work revealed that selenium and arsenic bind together to form an unusual molecule that passes harmlessly through the body.
Ingrid Pickering and Graham George. Photo courtesy Black Box Images.
Their findings, published in 2000 in the Journal of the American Chemical Society, suggest an intriguing possibility for the Bangladesh problem. That country’s soils, while high in arsenic, are low in selenium. And unlike arsenic, selenium is actually a nutrient the body needs.
“Selenium contributes to our general well-being, but it also gives protection against certain types of cancers,” Pickering says. “It’s very important in our diet.”
What if, Pickering and George thought, the Bangladeshis weren’t suffering from arsenic poisoning? What if the arsenic was binding with selenium in their bodies—the selenium already at low levels because of its rarity in the soil—to produce not arsenic poisoning, but something else entirely different? What if the Bangladeshis were suffering from acute and chronic selenium deficiency, whose symptoms resemble that of arsenicosis?
Easy enough to find out: ask some Bangladeshis to start taking daily selenium supplements and see if the symptoms persist. Clinical trials by an international team, involving researchers in the U.S., Bangladesh and Canada, are doing just that.
Researchers on site in Bangladesh take photographs of lesions on patients’ skin using a special “derma-light” camera. Then patients are prescribed selenium supplements and their skin is photographed again to record any changes. While it’s too early to reach conclusions, initial results from these clinical trials are encouraging.
For now, George and Pickering are working to nail down the synchrotron data. Analysis will continue at Stanford until suitable facilities come online at the Canadian Light Source (CLS) at the U of S. A powerful new BioXAS (X-ray absorption spectroscopy applied to biological systems) facility is currently in the planning stage and construction is slated to begin at the CLS in the near future.
Powerful electromagnets used in the Canadian
Light Source synchrotron at U of S. Photo courtesy CLS.
Back in Bangladesh, local doctors have been invaluable collaborators in the project, collecting blood samples from patients to make the first synchrotron analysis possible. The samples, however, must be prepared in a specific way. This wasn’t done correctly in the summer, so a member of the U of S team, research associate Satya Singh, will travel to Bangladesh to supervise the collection of more samples.
“Getting blood samples from rural Bangladesh back to this continent is not trivial,” George says.
Travelling in that country is a challenge—particularly this past summer, when all the research sites were flooded after torrential rains. Transportation and access depends on paying the right people at the right time. And the samples must be gathered and shipped back to North America in “cryo-shippers”—large vacuum bottles with interiors chilled to liquid nitrogen temperatures.
George explains that just getting the logistics sorted out is a success others will be able to model when tackling future research in the developing world.
“This will be the gold standard of how to do this in a rural Third World environment,” he says.
The international team is expected to have their results ready for publication in a major journal late in 2008.
Artist’s rendering of the Canadian Light Source expansion. Photo courtesy CLS.
What is a Synchrotron?
A synchrotron uses powerful electromagnets and radio waves to accelerate electrons in a huge ring-shaped vacuum chamber to nearly the speed of light. Each time the magnets force the electrons to change course, the electrons give off extremely brilliant, highly focused light.
Synchrotron light can be used to probe the structure of matter and analyze a host of physical, chemical, geological and biological processes. The light is directed down beamlines, where researchers choose infrared, ultraviolet or X-ray wavelengths and use a variety of techniques to analyze their samples. George and Pickering, for example, use X-ray absorption spectroscopy (XAS) in their search for the solution to the selenium-arsenic puzzle in Bangladesh.
Information obtained from synchrotron analysis can be used to help design new drugs, examine the structure of surfaces to develop more effective motor oils, build smaller, more powerful computer chips, develop new materials for safer medical implants, and help with clean-up of mining wastes, to name just a few applications.
Selenium-Rich Soils Set Saskatchewan Lentils Apart
Saskatchewan’s selenium-rich soils and status as the world’s largest exporter of lentils could position the province to help solve serious public health challenges in the developing world.
“It turns out that lentils grown in Saskatchewan are really quite high in selenium,” says Ingrid Pickering, who holds a Canada Research Chair in Molecular Environmental Science at the U of S.
This could be good news for people in the developing world who have no easy way to get enough selenium in their diet. While the element is toxic in higher doses, it is also a nutrient essential for bodily functions such as hormone regulation, immune system function and cancer prevention.
Millions of people around the world rely on protein-rich lentils as a dietary staple, and Saskatchewan is the world’s leading supplier. Almost all of Canada’s lentils are grown in the province.
Pickering is working with pulse crop expert Bert Vandenberg and his co-worker Dil Thavarajah at the U of S Crop Development Centre. Using tools such as those at the Canadian Light Source synchrotron, the team is examining selenium compounds in lentil varieties.
The aim is to determine if the selenium is in a form that can be easily digested and used in the body. This knowledge will guide development of possible future varieties of lentils with enhanced selenium nutrition.
