February 23rd, 2011
Air Pollution and Cocaine Among MI Triggers Analyzed in Lancet Study
Larry Husten, PHD
Air pollution is a weak cause of MI, increasing risk by only 5%, but because so many people are exposed to polluted air the population effect is quite large. By contrast, cocaine increases MI risk by 23 times, but does not have nearly as large an effect on the population. These are two of the key results from a study published in the Lancet. The authors analyzed data from 36 epidemiologic studies and calculated population attributable fractions (PAF) in order to perform a comparative risk assessment of multiple MI triggers.
Here are the calculated PAFs:
- traffic exposure: 7.4%
- physical exertion: 6.2%
- alcohol: 5.0%
- coffee: 5.0%
- air pollution: 4.8%
- negative emotions: 3.9%
- anger: 3.1%
- heavy meal: 2.7%
- positive emotions: 2.4%
- sexual activity: 2.2%
- cocaine use:0.9%
- marijuana smoking:0.8%
- respiratory infections: 0.6%
The authors concluded “that acute effects of both participation in traffic and exposure to particulate matter air pollution are substantial contributors to the triggering of myocardial infarction in the population. Improvement of the air we breathe is a very relevant target to reduce the incidence of this disease in the general population.”
In an accompanying comment, Andrea Baccarelli and Emelia Benjamin call the study “an exemplary piece of epidemiological work that furthers our understanding of myocardial infarction triggers. Their work stands as a warning against overlooking the public health relevance of risk factors with moderate or weak strength that have high frequency in the community.”
3 Responses to “Air Pollution and Cocaine Among MI Triggers Analyzed in Lancet Study”
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It is surprising that tobacco smoking or exposure is not on the list, but only marijuana smoking is. Why?
Competing interests pertaining specifically to this post, comment, or both:
none
Dr. Hyman– in the discussion section the authors explain that passive smoking is missing from their analysis because of a lack of data in individuals, but they note that their “conclusions for outdoor air pollution and those for passive smoking mutually support each other, even in terms of the relative magnitudes of the effect.”
I agree it would have been more helpful to readers if this article could have reminded us that the PAF (population attritutable fractions) for traditional risk factors like tobacco smoking (~60%) and hypertension (~35%) are much higher than those of the environmental exposures highlighted here (5-7% for air pollution). But I guess that might have detracted from their main argument, that the aggregate risk from multiple ‘less potent’ exposures is something we should pay more attention to.