Just shy of earning a Ph.D in economics, Associate Professor of Urban and Environmental Policy and Planning Mary Davis wavered in her commitment to the field. She consulted an online career questionnaire, hoping it would tell her to become a doctor - it confirmed, however, that she should, in fact, become an economist.
At last Friday's Taste of Tufts presentation, hosted ever week by the Experimental College, Davis said that she maintains a love-hate relationship with the discipline. She spoke about how she has worked to apply her academic training in classical economics to other medical fields, after completing her postdoctoral degree in biostatistics and environmental health at Harvard University. In particular, Davis discussed her research in occupational health studying fishermen and truck drivers.
"You have a group of people who tend to be overly exposed to an environmental hazard and there's a financial incentive for them to be overexposed," Davis said. "They're vulnerable in ways that the general population aren't, and more easily taken advantage of because of these financial incentives."
According to Davis, life in the fishing industry is ranked the most dangerous occupation in the United States. The Coast Guard reports that although there is no formal job training for fishermen, the majority of fatalities in fishing are often preventable with proper training and equipment. Literature on the subject says that fishermen tend to self-select into the job as a result of risk-loving personalities.
The Maine Marine Control and the Commercial Fishing Safety Council in Maine approached Davis for help in understanding the economic impact of increasing safety standards for the fishing industry. Davis looked into the existing standards and training procedures for fishermen. Finding a lack of information in the area, she began to collect this data herself.
"I paired with Marine Control and went out on water ... in the summer, winter, fall and spring, all the way up and down the coast of Maine, because there was no other way to get fishermen," Davis said. "What I found by talking to them and doing these surveys was that less than half of them were in compliance with the existing regulations. The idea of increasing and making regulations stronger when only half are at the current standards seemed pretty ridiculous."
Davis also reported that fishermen's unique perceptions of risk played into how new safety policies should be implemented.
"I definitely found that they were risk-loving personalities - they smoked more, reported they wore their seatbelts less [and] worked in other dangerous industries. Another important thing was that they underreported their own risk, but seemed to understand fishing is dangerous overall," Davis said. "There was this disconnect between their perceptions and reality that was really fascinating in this group ... an overreliance on common sense was really [apparent]."
Based on her research, Davis made recommendations to improve Maine's safety training and education. She also suggested potentially providing economic incentives for fishermen to purchase necessary equipment to improve safety.
At Friday's lecture, Davis discussed her research of the occupational health of truck drivers in the context of their exposition to air pollution, specifically hazardous diesel exhaust.
"All pollution is not created equal," she said. "You have these larger particles and then you're going down ... to get to diesel, which are really tiny. The smaller the particle, the farther it gets, and the smallest of particles get all the way to your lungs, and that's what matters for lung cancer," Davis said. "So size matters, but also composition. Diesel exhaust has this elemental carbon core, but it's surrounded by a lot of really nasty junk - metals, toxics, benzenes, things that we know cause cancer in general."
Davis pointed out that extensive research on diesel as an air pollutant has been conducted, but there was no established causality between diesel exhaust and cancer.
"Interestingly enough, diesel exhaust
until this past summer was not categorized as a known human carcinogen," Davis said. "So we knew that there were bad things that caused cancer on it, but we refused to regulate it in such a way that would show a causal link between the two."
Davis embarked on a project to prove it, using truck drivers as self-selecting subjects in the largest study of diesel exhaust in the world. Gathering data from 55,000 truckers of the International Brotherhood of Teamsters, the project traveled to 42 different cities in four to five years to look at the levels of air pollution truck drivers were exposed to over the course of their careers in the industry.
The results were a staggering indication that exposure to diesel exhaust causes lung cancer.
"The risk for truckers was 15 to 40 percent higher than the average person," Davis said. "The longer you worked in the trucking industry, the worse it was, the higher your risks were."
Davis' data, along with a separate National Institute of Occupational Safety and Health study on miners, this summer pushed the World Health Organization and International Agency for Research on Cancer to finally classify diesel as a known carcinogen."
Beyond her studies of occupational health, Davis at the lecture also touched on her work analyzing the relationship between economic recessions and health. According to Davis, most economists subscribe to the theory that unhealthy consumption patterns increase in times of relative wealth, suggesting that people are healthier during economic downturns. However, Davis took a different approach.
"Could I link the business cycle to air pollution trends? I'm trying to explain why people are healthier in bad economic times ... maybe people are healthier because the environment around them is healthier in bad economic times," she said. "No one really had looked at the environment as a way that these relationships were playing out. So I wanted to specially test with the diesel exhaust, since I had that data."
Davis looked at historical data of air pollution and unemployment in New Jersey and California and developed a regression model that controlled for factors including location, seasonal and time differences, demographics and environmental regulations. Using this model, she discovered a link.
"What I found is that economic bad times do have a significant effect. High unemployment was linked to low air pollution," she said. "When there was ... high trucking sector employment, there was more air pollution, too, and this was over a period of about 30 years. In New Jersey, she added, a 15 percent decline in exposure to diesel could be attributed to unemployment dips alone.
According to Davis, in California, there was a 16.8 percent decline in exposure to carbon monoxide and another 12 percent in nitrogen dioxide, both of which are air pollutants that come from traffic. However, Davis acknowledges that more research needs to be done.
"What is missing here are the health applicants. I can't say that people are healthier in bad economic times," she said. "I can say [that] the literature shows that air pollution links to bad health, and I can also show that recessions are linked to air pollution, but pulling it all together hasn't been done yet."
Now, Davis wants to take her work in environmental health and economics to a global scale. She is working on a project with Associate Professor of Economics Drusilla Brown, who is also the director of Tufts' International Relations Program, to study occupational health in sweatshops in Haiti. In her two trips to Haiti so far, Davis has also taken note of the severe air pollution and hopes to work with that problem as well.
"I took some air pollution monitors with me last time I was there and the levels that I found on the streets in Port-au-Prince driving in traffic were ten times what was reported in the literature ten years ago of the worst areas of Mexico City, which ... is kind of like the example, like Beijing, really the worst of the worst in the world," Davis said. "There's a big problem there, and I hope to move in that direction to more global issues as time goes on."
