Dr. Chris Le is looking at environmental contamination from a fresh perspective—inside the body.

With a three-year, US$375,000 grant from the American National Institutes of Health (NIH), the professor of public health sciences and his collaborator, Dr. Michael Weinfeld of the Cross Cancer Institute, are using DNA damage to measure exposure to environmental contamination. They are also interested in how cancer-causing agents such as arsenic accumulate and metabolize in the body.

"We often measure levels of environmental contamination," Le says, "but it's a long way from there to the body. if we can measure this so-called internal dose, it would be a lot more meaningful, because it takes a global account of what's happening in the body."

The importance of this research has been foregrounded by Le's work, much of it sponsored by the Natural Sciences and Engineering Research Council of Canada and American Water Works Association Research foundation, on the determination, metabolism, and toxicity of different types of arsenic. Though arsenic is just one of the elements Le and Weinfeld's research team are studying, it's a shocking example of how dongerous environmental contamination can be. Arsenic occurs naturally in both the earth and in small amounts in the body, but it's also a potent toxin—it was a favoured means of assassination in the Middle Ages because of its lack of colour, taste, and odour.

Le's research led him to gain new insights into arsenic poisoning arising from a chemical produced by the body as it metabolizes arsenic. This intermediate form is extremely toxic, which was a surprise to the medical and research community. Before Le's findings were published, it was thought that metabolic activity in the body made arsenic less toxic, not more so.

Le and Weinfeld came into prominence in the field of DNA damage four years ago, when they developed a technique to measure the damage that was 10,000 to 100,000 times more sensitive than other techniques then available.

-by Stephen Osadetz

Published Spring/Summer 2002.