Unexpected consequences of global warming: kidney stones

Paul Simons, Times Online 16 Jul 08;

Climate change is having some unexpected consequences all over the world. In the Arctic, Inuit communities are seeing their first wasps, and radio broadcasts have been needed to caution about the hazards of trying to touch the wasps, which are flying farther north as the Arctic warms.

European brewers are facing a crisis as their traditional hops are wilting from drought and heat, and a programme has begun to make them more drought-tolerant.

The famous geysers of Yellowstone Park, Wyoming, are slowing down; Old Faithful’s regular eruptions have shifted by an extra 16 minutes in eight years. The reason is that the geysers’ water supplies are dwindling as the climate turns drier.

Perhaps the most unexpected impact of global warming is a rise in the number of kidney stones. These painful stones result from salts crystallising in the kidneys, often caused by dehydration.

The hotter the climate, the more cases of kidney stones occur and the southern US regions get around 50 per cent more cases than northern states. The number of cases has been rising since temperatures began to warm noticeably from the late 1970s. As the climate warms, the zone of high risk for kidney stones is expected to push northwards, and by 2050 an estimated 1.6 million new cases are predicted.

Climate change: Warming may cause increase in kidney stone cases, say US scientists
Elana Schor, The Guardian 15 Jul 08;

Endangered species. Economic decay. Extreme weather. The list of climate change's destructive costs is long, but US scientists today proposed adding one more: millions of new kidney stone cases.

The proven link between kidney stones and warm temperatures means that climate change could dramatically increase the number of US cases in the coming years, according to a study published today in the renowned journal Proceedings of the National Academy of Sciences.

The increased risk of kidney stones -- which come from painful mineral deposits in the urine -- could lead to as much as $1.3bn in increased medical bills by the year 2050, the team of Texas urologists behind the study estimated.

The study used two competing models to estimate the reach of new kidney stones brought on by global warming, using data from the UN intergovernmental panel on climate change (IPCC).

One model predicted a steady growth in new cases as global temperatures rise, and another predicted that new cases would plateau after temperatures reached 15 degrees Celsius.

The first model projected that stones would become more prevalent in the states of Texas, Florida, California, and the east coast of the US. The second model yielded the bulk of its new cases in the mid-west US, including 100,000 in Chicago alone.

The US would experience between 1.6m and 2.2m new kidney stone afflictions by 2050 under both scenarios.

Kidney stones will afflict 10% to 15% of the US population at a total treatment cost of about $2bn per year, according to previous scientific studies. Nearly double that number of cases has been reported in the Middle East, where temperatures are uniformly balmy.

The famously unbearable pain caused by passing a kidney stone through the body can cause nausea, vomiting, and blood in the urine.

But there is an easy way to decrease the risk of climate-induced stones, according to Dr Mark Litwin, a professor of urology and public health at the University of California in Los Angeles.

"The irony is, the cure is fairly simple," Litwin told Science News magazine. "Just drink more water."

Climate change to cause rise in kidney stones
Catherine Elsworth, The Telegraph 15 Jul 08;

Global warming could lay waste to vast tracts of the earth - and may also lead to more Americans suffering kidney stones, scientists have warned.

Kidney stones, which can be extremely painful, are often caused by dehydration as the body is unable to flush minerals out of the system.

Researchers say that as temperatures rise, the driest parts of the US could see a 30 per cent increase in kidney stone disease.

The study by University of Texas researchers predicts that warmer temperatures could extend America's existing "kidney stone belt", an area of the South East where men have been found to be twice as likely to develop kidney stones as in the North East.

The claims, published in the Proceedings of the National Academy of Sciences, are based on existing data on kidney stone incidence and climate change projections made by the UN Intergovernmental Panel on Climate Change in 2007.

The increase would represent between 1.6 million and 2.2 million cases by 2050, according to the study, potentially pushing annual treatment costs up to around one billion dollars.

"This study is one of the first examples of global warming causing a direct medical consequence for humans," said Margaret Pearle, professor of urology at University of Texas Southwestern and senior author of the paper.

"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."

Tom Brikowski, the study's lead author, compared kidney stone rates with UN forecasts of temperature increases and created two mathematical models to predict the impact on future populations.

According to one set of data, the existing "kidney stone belt" comprising southeastern states such as Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee would grow to encompass over half the US population by 2050.

The other model predicts the increase would be concentrated in the upper Midwest.

The study adds that "similar climate-related changes in the prevalence of kidney-stone disease can be expected in other stone belts worldwide."