Air Date: Week of September 3, 2010

A recent long-term study out of Germany found that the closer participants lived to major roads, the greater their risk of developing type 2 Diabetes. Host Jeff Young talks with Dr. Wolfgang Rathmann, the study leader and researcher at Dusseldorf University's Diabetes Center, about what he found.

Transcript

YOUNG: It’s Living on Earth, I’m Jeff Young. And, we already know that air pollution harms hearts and lungs. But a study in the journal Environmental Health Perspectives adds a new hazard: air pollution could also lead to type 2 Diabetes. A long-term study from Germany has some intriguing results. Dr. Wolfgang Rathmann is the study leader. He's a researcher at Dusseldorf University's Diabetes Center. Dr. Rathmann, welcome to Living on Earth.

RATHMANN: Hello!
YOUNG: Now, your study followed about 1,800 healthy middle-aged German women over the course of almost two decades, in some cases. Tell me what you found.

RATHMANN: Yes, we have investigated the relationship between air pollution and new cases of type two diabetes in a cohort of 55 year old women, which lived in the industrialized route of West Germany, and also a control group in non-industrialized towns nearby. And between 1990 and 2006, 178 women were newly diagnosed with type two diabetes in this cohort. And, we found that exposure to components of traffic pollution, particularly nitrogen, dioxygen, fine particulate matter were significantly associated with a higher risk of type 2 diabetes in these women.
YOUNG: Well, how might air pollution be contributing to diabetes?

RATHMANN: We think that inflammation plays an important role. We know form several studies that low-grade inflammation is associated with impaired glucose metabolism and also with type two diabetes. Because these inflammatory markers impair insulin action and have affects on several cells that are related to the development of type two diabetes. There was a publication on an experiment that mice were exposed to air pollution and there was also a control group of mice with normal air. And, what was interesting was that those mice who were exposed to air pollution had an inflammatory response. They had higher immune makers in the blood, and also what was shown in this study was also, that they had some disturbed glucose tolerance.

YOUNG: How significant a factor do you think this is? I mean, what we hear mostly about is diet. Is this on par with diet in terms of your chances of developing diabetes?

RATHMANN: Obesity, low physical activity, a certain diet which all triggers stimulation of the immune system and we think that traffic-related air pollution is another player in this concept. We know from several pervious epidemiological studies that people who live in an urban region have a higher likelihood to develop type two diabetes than people in rural areas. And this is especially true in developing countries undergoing rapid industrialization. We found that diet or physical activity do not completely explain the increased diabetes risk.

YOUNG: So there’s something about air pollution that’s causing our bodies to respond with this inflammation, and there’s something about that inflammatory response that’s leading us to be more vulnerable to diabetes?

RATHMANN: In a sense, yeah. And, what comes first is the question. First inflammation and then you have some air pollution and then you get diabetes…I think it’s what we call in medicine a multiple hit. So, if you have several risk factors hitting in the same direction like obesity, smoking, low physical activity, genetics and then air pollution, and they all point in the same direction that your immune system is activated but higher than in healthy people, then this will make disturbances in the body that the insulin action is disturbed or impaired which eventually leads to type two diabetes. So, we don’t think that air pollution is the one and only factor, but it’s a new one, and another one. And, as we said, a preventable one.

YOUNG: And in your study, the closer someone lived to the highway, the higher their chance for diabetes?

RATHMANN: That’s correct. We found that living within 100 meters of a busy road, which means there are more than 10,000 cars per day, more than doubles the risk of diabetes. And this was in particularly true in women with a lower educational level.

YOUNG: You say this is potentially a modifiable risk factor. How might we modify this risk factor for diabetes, if in fact the other studies confirm what you found?

RATHMANN: The importance may be even more outside Germany or the US, because we know that in some Asian and Latin American countries, air pollution is over ten times higher. For instance, in China, we saw a huge increase, more than ten-fold higher diabetes prevalence, during the last 20 years or so, and this can not only be attributed to physical activity or changes in diet alone. Therefore, preventive actions should be carried out to reduce air pollution, in order also to prevent diabetes. These actions can also be expected to have additional benefits because air pollution increases the risk of cardiovascular and lung diseases. And, I expect that with in the next few years we see another set of new risk factors emerging, which are more related to the environment and not to the behavior of the patient. And this will lead to new perspectives in prevention.

YOUNG: Dr. Wolfgang Rathmann at Dusseldorf University's Diabetes Center. Thank you very much!

RATHMANN: You’re welcome!