Alarmist Claims Global Warming Causes Increase in Kidney Stones

Published October 9, 2008

New research by University of Texas-Southwestern professor Margaret Pearle claims global warming will cause an increase in kidney stones.

Others, however, dismiss the claim as just another example of over-the-top global warming alarmism, citing other research on factors known to be associated with kidney stone development.

Pearle’s paper, “Climate-related increase in the prevalence of urolithiasis (kidney stones) in the United States,” appears in the July 15 Proceedings of the National Academy of Sciences.

Dehydration Link Imagined

Pearle’s paper speculates people in warmer climates dehydrate more frequently, which can be a factor in kidney stone development. The paper also speculates heat-related stress may be a factor in kidney stone development, and warmer temperatures will mean more heat-related stress.

Pearle bases her assertion on the fact that people in the U.S. Southeast have a slightly elevated incidence of kidney stones relative to the rest of the nation.

“This study is one of the first examples of global warming causing a direct medical consequence for humans,” Pearle told the London Telegraph. “When people relocate from areas of moderate temperature to areas with warmer climates, a rapid increase in stone risk has been observed. This has been shown in military deployments to the Middle East, for instance.”

Other Factors More Important

Several factors, however, limit the reliability of Pearle’s asserted link between global warming and kidney stones.

The most authoritative medical studies and texts agree the vast majority of all kidney stone cases are due to inherited tendencies, not outside factors. The Merck Manual, 18th edition (2006), like all medical texts, declares more than 75 percent of kidney stones in humans are due to inherited tendencies to excrete high levels of calcium, uric acid, and some other crystals.

Pearle’s work says little about the overwhelming influence of heredity, as opposed to geography and climate, on kidney stone development.

Moreover, residents of the American Desert Southwest region show no higher incidence of kidney stones than do residents of other parts of the country.

Warming a Net Health Benefit

At the 2008 International Conference on Climate Change, held in March in New York City, Dr. Paul Reiter, chief of the Insects and Infectious Disease Unit at the Institut Pasteur in Paris, said the medical community should stop trying to panic the populace about negative health effects of warming.

According to Reiter, even when certain negative health factors can be tied to warmer temperatures, many other negative health factors are tied to cooler temperatures.

On balance, warm temperatures have a net beneficial effect on the health of the world’s population, Reiter explained.

Alleged Link ‘Absurd’

“A link between global warming and kidney stones is on its face absurd,” said Dr. Jane Orient, executive director of the Association of American Physicians and Surgeons. “Even a 6 degree increase in temperature does not by itself lead to kidney stones.

“Assuming for the sake of argument that global warming is occurring and humans are to blame, many of the asserted health risks are not supported by science,” Orient noted. “They tend to be speculative and one-sided, looking for isolated nuggets of harms without considering the counterbalancing benefits.”

“Perhaps we could note that millions of people have voluntarily moved to the South and Southwest, in spite of [kidney] stones,” said Craig Loehle, Ph.D., principal scientist at the National Council for Air and Stream Improvement.

John Dale Dunn, M.D., J.D. ([email protected]) is a civilian emergency medicine faculty member at the Carl R. Darnall Army Medical Center and policy advisor to The Heartland Institute and the American Council on Science and Health.