Sep. 18 2019

Water Is the Wellspring of Public Health

Water is fundamental to life and health. In drought, crops wither and people die; in a deluge, water destroys homes, brings disease, and displaces populations. As extreme weather becomes commonplace with climate change, public health researchers at Columbia University Mailman School of Public Health are working to understand the threats and develop interventions to protect human health—research in sync with the priorities of the larger university.

This fall, Columbia University is launching the Year of Water, a multidisciplinary initiative to highlight the social, political, cultural, and economic dimensions of H2O. As part of this programming, next spring’s annual Sewell lecture in Environmental Health Sciences at Columbia Mailman will focus on water issues. As any first-year MPH student can tell you, water has been a central concern of public health dating back to the origins of the field.

In 1854, English physician John Snow solved a mystery that gave rise to epidemiology and public health, tracing a cholera outbreak in London to a single contaminated well. After he made this discovery, he removed the pump handle to prevent further infections. In the decades that followed, his methods inspired fundamental changes to urban water and sanitation systems that contributed to dramatic gains in life expectancy over the last 150 years.

Water and Sanitation

Improvements to water and waste systems are far from complete; clean water and proper sanitation remain out of reach for much of the world’s population. According to the World Health Organization, a quarter of the planet (1.8 billion people) do not have a proper place to defecate; slightly more than one-tenth of humanity (790 million people) do not have an adequate water supply.

“In the poorest settings, proper sanitation is usually more protective against malnutrition and child death than is safe water,” says Leslie Roberts, a professor of Population and Family Health who trained as a water engineer and now teaches a class in water and sanitation in emergencies. Nevertheless, many countries prioritize large water projects, some of which can have unintended consequences. The Ilisu dam in Turkey, for example, has led to water shortages in neighboring Iraq.

One consequence of poor sanitation and contaminated water is diarrheal diseases, which the U.S. Centers for Disease Control and Prevention estimates account for one in nine child deaths worldwide, making diarrhea the second leading cause of death among children under the age of 5. A study in the Chobe River valley in Botswana by Jeffrey Shaman, professor of Environmental Health Sciences, found that cases of diarrhea in young children spiked during extreme climate conditions, in both the wet and dry seasons. A second study reported on a method to forecast childhood diarrheal disease based in this region.

“In Southern Africa, precipitation is projected to decrease,” says Shaman, an expert in hydrology and director of the School’s Climate and Health program. “This change, in a hydrologically dynamic region where both wildlife and humans exploit the same surface water resources, may amplify the public health threat of waterborne illness. For this reason, there is an urgent need to develop the water sector in ways that can withstand the extremes of climate change.”

Climate Change and Food Security

Look in the sky and you’ll likely see Earth’s most abundant greenhouse gas—not carbon dioxide, but water vapor in the form of clouds. Like CO2, water vapor traps heat in the atmosphere, amplifying the effects of climate change. As the poles warm faster than other latitudes, weather patterns are destabilizing, leading to powerful storms like hurricane Dorian that wreaked havoc in the Bahamas in early September.

Lewis Ziska, a plant physiologist and professor of Environmental Health Sciences, studies the effects of climate change on agriculture, mostly through the lens of warmer temperatures and higher concentrations of atmospheric CO2. But he also recognizes the destructive power of destabilized weather on crops, whether droughts like the one currently threatening Somalia, or heavy rains like those that flooded the Midwest this past spring. “The conditions were too wet,” says Ziska. “Farmers weren’t able to plant their crops.” 

To make agriculture more resilient to the changing climate, Ziska calls for a transition away from industrial agricultural practices that rely on a handful of crop varietals in favor of an approach closer to the kind practiced for most of human history. Since the first fields were planted millennia ago, humans bred crops to flourish under many different and difficult conditions, including flooding and drought. In the same way, he says we should tap this rich library of crop varieties to find those that are best suited to rising temperatures and CO2. In a paper published by the Royal Society, he details a method to identify these plant strains based on their physical characteristics and genetic makeup. Scientists in Australia, China, and Japan are currently testing different rice strains for these same characteristics.

Meanwhile, scientists in the School’s Center for Infection and Immunity have identified threats to mariculture, pinpointing the viruses responsible for outbreaks devastating farmed populations of salmon and tilapia.

Metal Menaces

Worldwide, one of the biggest threats to safe drinking water is arsenic, a metalloid without taste or an odor. Nowhere is this threat more apparent than Bangladesh, where a 2010 Columbia Mailman study estimated that one in five deaths in the country was associated with exposure to well water with elevated arsenic. In the years since a program implemented by the research team supporting the use of safe wells has seen considerable success.

In the U.S., studies of arsenic contamination by Ana Navas-Acien, professor of Environmental Health Sciences, have zeroed-in on specific health threats to young people, including a thickening of the heart’s main pumping chamber. Further research will look at whether the changes to the heart structure are reversible if exposure is reduced. “Some changes have occurred in water sources in the study communities, and it will be important to check the potential health impact of reducing arsenic exposure,” she says.

Markus Hilpert, an associate professor of Environmental Health Sciences with a background in physics, is interested in the fluid dynamics of fossil fuel-related contaminants like gasoline. His research has found that small droplets of fuel penetrate the concrete slabs of gas stations, potentially affecting the health of nearby communities who rely on well water.

There is no more stark example of the link between clean water and health than the case of Flint, Michigan. When the city sought to save money by switching its supply from Lake Huron to the corrosive Flint River, in 2014, lead leached from water pipes into household drinking water, exposing 100,000 mostly African-American residents to dangerous concentrations of the heavy metal. A 2016 analysis by Peter Muennig, professor of Health Policy and Management, estimated that the resulting lead poisoning will cost up to $400 million—far more than the savings from switching water sources—when accounting for health-related losses in economic productivity, higher welfare use, and additional criminal justice system costs.

In thinking about the Flint crisis, David Rosner, a historian and professor of Sociomedical Sciences, says we should not forget the toxic legacy of the automotive industry. At its height in the early 1980s, General Motors employed as many as 80,000 workers at a series of enormous factories situated along the Flint River. A network of suppliers, many based upriver from Flint, produced components such as paint and batteries—all which contained lead.

“The indignities and bodily insult today’s children face in Flint is horrifying,” Rosner wrote in an editorial in the American Journal of Public Health. “But, even more horrifying is that this city and its children have been poisoned in one way or another for at least 80 years.”


Photos (from top): pixelfusion3d/iStock via Getty Images; N_u_T/iStock via Getty Images; shotbydave/iStock via Getty Images; ehrlif/iStock