Post-Gazette Devra Lee Davis Click photo for larger image. Background Age: 59 Position: Director, Center for Environmental Oncology, University of Pittsburgh Cancer Institute. Education: University of Pittsburgh, bachelor's degrees in physiological psychology and sociology of science, 1967; University of Chicago, Ph.D., science studies, 1972; master's degree in epidemiology, Johns Hopkins University School of Public Health, 1982. Books, publications: "When Smoke Ran Like Water -- Tales of Environmental Deception and the Battle Against Pollution," National Book Award finalist, 2002; More than 80 articles in peer-reviewed journals and more than 20 book chapters. Listen in Audio excerpts from the interview with Dr. Davis: Low-level pollution and its relationship to illness, including her own adult-onset asthma. Hormone exposure and its possible connection to cancer. Her personal philosophy on the relationship between environment and cancer. Pumping gasoline and the concept of prudent risk. The no-regrets approach to reducing exposure to pollution. How much proof should be enough to take action on environmental pollution?

In her 50s, Devra Lee Davis was diagnosed with asthma.

It may seem a cruel irony that one of the nation's leading experts on air pollution and health would come down with a respiratory condition, but it didn't surprise Dr. Davis, given where she grew up.

She is a native of Donora in Washington County, site of one of the worst air pollution disasters in modern history. For four days in October 1948, an atmospheric inversion of cold air trapped the smoke and fumes from Donora's steel mills, coke and zinc furnaces and coal stoves in a layer of thick fog that enveloped the town.

By the time it was over, 20 people had died and nearly 6,000 had become ill. Many residents, including Dr. Davis' mother, grandmother and uncle, would suffer health problems for years to come.

Dr. Davis, 59, the director of the Center for Environmental Oncology at the University of Pittsburgh Cancer Institute, was only 2 when the disaster struck. She was in college before she learned about the infamous inversion, and it took a conversation with her mother to remind her of what it had been like to grow up in a Monongahela Valley steel town.

"Remember all that grime we had on the cars," her mother said, "how we had to drive with the headlights on in the afternoon? How the sun didn't shine for days at a time? Remember how women always had their curtains hanging out to dry every week?

"A lot of us gave up on curtains altogether," her mother said. "Venetian blinds were better, because they could be wiped down."

The Donora incident became the jumping off point for Dr. Davis' 2002 book, "When Smoke Ran Like Water -- Tales of Environmental Deception and the Battle Against Pollution," which was a National Book Award finalist that year.

The book goes far beyond the Donora incident. It tells of other air pollution crises, like the killer fog in London in 1952. It describes the years of battles it took to remove lead from gasoline. It explores the link between environmental toxins and various ailments, such as breast cancer and male reproductive problems.

And it repeatedly lifts up one of her central beliefs -- that long-term exposure to low doses of pollution can be just as damaging as the occasional catastrophe.

"The real lesson of Donora and London," she wrote, "is not just that brief, intense episodes of visible air pollution from industrial sources or coal fires can quickly fell the weak. It is that daily exposure to low levels of pollution that could not be seen or smelled can ruin the health of millions."

The book was indirectly responsible for Dr. Davis getting her present job at Pitt's Cancer Institute.

When she was bringing her mother to Pittsburgh for cancer treatment near the end of her life, Dr. Davis found out that the institute's director, Dr. Ronald Herberman, wanted to speak with her. He told her he had read her book, and asked her to think about overseeing a center to study the environmental causes of cancer and ways to prevent the disease.

"And that put me on the spot," she recalled, "because it's really a lot easier to criticize things than to come up with what you are going to do."

When she began her work as director of the Center for Environmental Oncology last year, Dr. Davis was guided by a philosophy she had developed over a lifetime of research: you don't need to prove it's going to rain before you carry an umbrella.

In her field, that means scientists should not have to prove beyond all doubt that an environmental toxin is causing harm before officials decide to do something about it.

"Public health studies, in my view, should never be the requirement before we take action. Should we do these studies? Absolutely. Should we say that until we have the results we can't tell you what to do? No.

"Think of it like this. What if you went to the doctor and said, 'My head hurts,' and the doctor said, 'Come back in six years, when I've finished my study.'

"We don't have the luxury to do that on so many of these environmental issues."

As Dr. Davis and her colleagues seek sufficient evidence to call for action, they are exploring several different concerns.

One is the high incidence of breast cancer among younger black women, and the fact that breast cancer tends to be more aggressive in black women of all ages.

The center is investigating whether there is a link to certain cosmetics and hair treatments marketed to African Americans that contain placental extracts. Because there is a connection between estrogen exposure and breast cancer, and because animal placentas often contain such hormones, Dr. Davis said, it's worth finding out whether personal care products could be a factor.

The center also wants to see whether things in the environment could be interacting with black women's genes to trigger higher risks of the disease.

Another research area is the different forms that estrogen can take in women's bodies. Some forms help repair cells and prevent cancer, while others have the opposite effect.

Once more is known about which forms of estrogen are most dangerous, Dr. Davis said, the center would like to develop blood or urine tests that could predict the chances of getting cancer and develop nutritional strategies to decrease the risk.

The heavy publicity in recent years on decoding the human genome and other genetic research may have given some people the impression that most cancer is caused by inherited defects, Dr. Davis said. But in the case of breast cancer, she has written, "fewer than one in 10 cases ... occurs in women who have inherited genetic defects. That means that most cases of cancer are not born, but made."

Dr. Davis feels the center has come along at a propitious moment, when many Americans are paying more attention to what they eat, what they put on their bodies and what they use to clean their homes.

"We're simply riding the wave of a growing public interest in seeing that we're living healthier in our homes, schools and communities."

Of course, she acknowledges that not everyone feels the environment is a major cause of illness and death.

"Some people look at these problems and say we don't have proof that people are sick or dying because of the environment," Dr. Davis said. "To them, the question of proof is having enough dead or sick people where you can show that that gun fired that bullet into that person at that time to cause that illness."

Public health studies can rarely provide that level of certainty, she said, which helps explain why it took so many years to put warning labels on cigarettes and remove lead from gasoline.

Often, she said, "people who take that view tend to work for a number of the industries that are profiting from the continued use of these products."

But she believes most Americans today are not willing to blindly accept industry viewpoints on pollution and toxins.

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"People are not accepting that the price of business as usual is more asthma for your children, more chronic obstructive pulmonary disease for others, a damaged nervous system, workers who have to retire early -- I think there's really broad support for the idea that we can get it right."

If the Center for Environmental Oncology does begin to recommend avoiding certain products or adopting certain diets or lifestyles, it will do so based on that "umbrella before the storm" philosophy.

"Look, we are not going to tell you that if you do this or you don't do that, we guarantee that you will not get cancer. Because we're not stupid -- we understand that it's a bit of a crap shoot.

"All we can say is this: Based on what we know, there are good strong scientific reasons to reduce your use and exposure of certain things, to seek safer alternatives, to try to come up with more efficient, less polluting technologies.

"It's what I call the 'no regrets' policy."