Health risks heating up? Global warming could affect patient symptoms
■ Physicians could be called upon to interpret the potential impact of climate change on individual health.
By Susan J. Landers — Posted April 21, 2008
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Jeffrey G. Demain, MD, has only to step outside his door at the Allergy, Asthma and Immunology Center of Alaska in Anchorage, where he is the director, to know change is in the air -- it's balmy.
Global warming, which may still be a glimmer on the horizon for the lower 48 states, is all too apparent at northern latitudes like Alaska, where temperatures have warmed by an average of 2 degrees Celsius during the past 50 years, Dr. Demain reported at the Annual Meeting of the American Academy of Allergy, Asthma and Immunology in Philadelphia last month.
That may not sound like much of a heat wave, but it has been cited as the reason for a cholera outbreak from oysters harvested in unusually warm water off Alaska's south coast. And it was blamed for the appearance of hordes of stinging yellow jackets in Fairbanks that resulted in many emergency department trips and some deaths.
Allergy season also starts earlier and ends later, thanks to the lengthened growing season. This expanding season mirrors what Dr. Demain sees as his expanding role as an interpreter of climate change for his patients. He is trying to translate the big-picture health threat many attribute to global warming to its impact on individuals.
"Patients need to be aware that what they remember from 10 years ago, or even five years, may be different now. If patients plan an outing and think they have never had an [allergy] problem after the first of June, they may now have a problem in the third week of June."
Global warming has made headlines in the past year. Former Vice President Al Gore and the Intergovernmental Panel on Climate Change, a body established by the World Meteorological Organization and the United Nations Environment Programme, shared the 2007 Nobel Peace Prize for efforts to disseminate knowledge on man-made climate change. Meanwhile, the World Health Organization is monitoring the health risks posed by a warming planet, as is the Institute of Medicine.
The earth's climate is out of balance, according to the American Geophysical Union, a scientific society in Washington, D.C., that studies the earth and its environment in space. The group attributes temperature rise to increased amounts of greenhouse gases, including carbon dioxide, and recommends cutting CO2 emissions in half by the end of the century to halt this trend.
Although global warming is broadly recognized, the reason for it is still the subject of some speculation. "I don't think there are skeptics that the world is warming, but there are skeptics as to why," Dr. Demain said. While greenhouse gases are the prime suspects, increases in the number of solar flares has also been suggested.
Regardless of cause, the health risks posed by climate change are real. Even if human activities turn out to have had a negligible impact, many believe it wouldn't hurt to err on the safe side and take steps to reduce our collective carbon footprint.
Medical groups are among those urging such actions. The American Medical Association promotes programs that prevent or reduce the human and environmental health impact from global climate change and environmental degradation.
The American Public Health Assn. recently determined the threat of climate change on health is "extremely serious" and noted a convincing case has been made implicating greenhouse gases as the prime perpetrators. The theme of the APHA's National Public Health Week, scheduled for April 7-13, was Climate Change: Our Health in the Balance.
"The verdict is in: Climate change is real," concluded WHO Director-General Dr. Margaret Chan at a December 2007 meeting at the National Institutes of Health. "The consequences are already being felt in ways that can be measured."
More pollen means worse allergies
One of those measurable consequences is the increase in the number of people with allergies and asthma, said Paul R. Epstein, MD, MPH, associate director for the Center for Health and the Global Environment at Harvard Medical School in Boston.
The longer growing season may be one reason for this jump, but Dr. Epstein makes the case that increases in the amount of carbon dioxide in the air also boost plant growth, particularly that of weeds, fast-growing trees and poison ivy.
"When ragweed is grown in conditions with twice the ambient level of carbon dioxide, the stalks sprout 10% taller than controls but produce 60% more pollen," wrote Dr. Epstein in a 2005 New England Journal of Medicine article.
"So something everybody is seeing in their offices is allergies, asthma and skin reactions," he said.
Christine Rogers, PhD, assistant professor in environmental health science at the University of Massachusetts, Amherst, has researched the link between rising CO2 levels and pollen measurements. "As far as health risks go, global warming is a problem. It changes the timing of plants and that of the presentation of allergens."
But whether more people will become allergic with this lengthy growing season is one of those unanswered questions, she said.
It is also difficult to know whether there will be more patients with asthma because of burgeoning pollen counts. Although you can build a hypothetical case that global warming is worse for those with allergies, it is harder to attribute a growth in the number of people with asthma to a warming planet, said Christopher C. Randolph, MD, associate clinical professor of pediatrics at Yale University School of Medicine in New Haven, Conn., and a clinician in Waterbury, Conn.
People with exercise-induced asthma actually could benefit from a warmer and more humid climate. "Cold, dry air is the worst enemy for the athlete in terms of exercise asthma," Dr. Randolph said.
Of course, no one is touting the benefits of these temperature trends, including Dr. Randolph. As a matter of fact, Stanford University Professor of Civil and Environmental Engineering Mark Z. Jacobson, PhD, recently produced more evidence for why global warming is a bad idea. He explained in a recent study how CO2 is directly responsible for killing people.
In an article in the Feb. 12 Geophysical Research Letters, Dr. Jacobson wrote that for every 1 degree Celsius rise in global temperatures caused by carbon dioxide, the resulting air pollution would lead to about a thousand additional deaths and many more cases of respiratory illness and asthma in the United States. Temperatures across most of the U.S. as well as the planet are estimated by the intergovernmental panel to have already warmed about 0.6 degrees Celsius over the past 100 years.
Donning a public health hat
With evidence building that humans well may be soiling the planet's air and perhaps impairing the ability of future generations to take a deep breath, Howard Frumkin, MD, MPH, DrPH, director of the National Center for Environmental Health/Agency for Toxic Substances and Disease Registry at the Centers for Disease Control and Prevention, is encouraging the concept of caring for the planet, a concept that is echoed strongly by the AMA.
Association policy encourages physicians to be spokespersons for environmental stewardship and to discuss relevant issues with patients when appropriate. The AMA also urges the medical community to reduce or recycle waste and dispose of medical waste in a safe manner.
Dr. Frumkin said his own thinking evolved as he moved from being a clinician, who focused on the individual patient, to public health, with thoughts about caring for the community. Now, he considers a third area of care, Dr. Frumkin explained at the APHA's annual meeting last November. "We need to think futuristically several generations out."
Although the health sector may not be considered a big player in global warming, it does represent about a sixth of the economy and offers opportunities to reduce energy consumption and greenhouse gas emissions, Dr. Frumkin said.
He serves on a steering committee that produced the "Green Guide for Health Care," a document designed to help hospitals and clinics build and sustain environmentally friendly facilities. The guide was developed by the Center for Maximum Potential Building Systems, a nonprofit green building group in Austin, Texas, and Health Care Without Harm, an international coalition of about 460 groups in more than 50 countries that was founded to create a health care system that is safer for the environment.
Dr. Frumkin also acknowledged that communicating effectively about the health risks of climate change is difficult for a number of reasons. "It is apocalyptic and highly technical, and no one understands it well. It is also unprecedented and scary. It implies that we need to think about behavior change, and for those of us who are comfortable living our lifestyles, one may recoil from behavior changes."
Rather than talking about the threats, he suggested taking a more positive approach. For example, planning for future heat waves -- an anticipated result of global warming that seems already to be occurring -- could include promoting a buddy system not only to protect vulnerable people but also to encourage a sense of community and build social capital, all of which are good for health, Dr. Frumkin said.
He also spun out a healthy scenario that involves parents walking their children to school rather than driving: more physical activity for parents and children, decreased risk of injury, building of social capital by meeting and greeting neighbors, decreased risk of osteoporosis, fewer contributions to air pollution and reduced need for asphalt, which will free up funds for public health, law enforcement and education.
"The co-benefits we can enjoy from addressing global climate change are enormous," he said. "Public health very much has a role at the table in assessing the health implications and the steps we take as a society to address climate change."