Earth, Air & Human Health
The work of Lamont scientists also addresses human health, from well-water quality near hydraulic fracturing sites and arsenic-contaminated land in Bangladesh to air quality for urban cyclists.
Lamont scientists are providing the analysis needed to recognize the risks and find solutions.
Battling the Largest Mass Poisoning in History
What has become known as the largest mass poisoning in history started underground, where water filters through the rocks beneath South Asia.
In the 1960s and ‘70s, international development agencies began drilling shallow wells to replace sewage-laced surface water supplies that had been serving for drinking water, but there was a problem that wouldn’t begin to show itself for several years: the new wells were bringing up water contaminated with naturally occurring arsenic. The result has been an epidemic of heart disease, cancers, lung problems, and compromised child development.
Researchers at Lamont, in collaboration with Columbia’s Mailman School of Public Health, have been on the front lines of the response since 2000. They are currently leading a wide range of initiatives. Lamont scientists are testing sediments to better understand the source of the problem and helping plan safer wells. They also developed simple tools to speed testing and cataloging of wells, including cheap, easy-to-use field water-sampling kits and cell-phone technology to register results to a central database.
Traces of the arsenic are locked into many rocks and sediments around the world. But studies by scientists at Lamont have shown that under certain natural conditions, these may release arsenic into drinking-water aquifers. Estimates suggest that some 140 million people in 70 nations are exposed to unsafe levels of arsenic in well water.
Southeast Asia—Bangladesh in particular—is ground zero. About 97 percent of Bangladesh’s rural population depends on community and private wells. By 1999, it was shown that half of those wells were contaminated. Millions more people are drinking from unsafe wells in India, Pakistan, Nepal, Cambodia, Myanmar, and Vietnam. Other countries with widespread problems include China, Mongolia, Chile, Argentina, Mexico, and the United States.
The first signs of trouble appeared in southwestern India in the 1980s, when large numbers of people started turning up with previously unseen skin lesions. Testing showed that many wells were drawing up arsenic at 10 to 100 times accepted safe levels.
Bangladesh and the other heavily affected southeast Asian countries have one factor in common: Much of their land rests on vast piles of sediments eroded out of the Himalayas and dumped onto river deltas. Many of these sediments contain arsenic, stuck to rusty iron-oxide particles, where it can’t do any harm. But studies by Lamont scientists and others show that the arsenic often can get into groundwater when organic compounds from plant matter percolate through shallow zones, where bacteria break them down. The decay process uses up dissolved oxygen in the water, and when the oxygen runs out, the bacteria eventually turn to the iron oxides for oxygen. This reaction sets the arsenic loose, to be dissolved in the water.
In Bangladesh, shallow sediments laid down in the last 5,000 years are the most hazardous. Safer water lies deeper, among sediments more than 12,000 years old, but a deeper well can cost 10 or 20 times more.
Rapid urbanization and expansion of intensive irrigation are also exacerbating the problem. Massive deep groundwater pumping to feed the municipal water supply of Dhaka appears to be pulling water in from neighboring, shallower aquifers. It is feared that this process—happening around other fast-growing cities as well—could eventually draw contaminated water into once-safe water sources.
A recent study led by Lamont’s Alexander van Geen shows that this may already be happening outside the booming city of Hanoi. There, pumping has moved water from a contaminated aquifer in the suburbs more than a mile toward the more populated center. The movement of arsenic itself seems to be slowed down by natural buffering processes, but the arsenic may already be moving in and could become a problem in Hanoi and elsewhere within decades, says van Geen.
The rapid expansion of deep pumping for crop irrigation may pose an even more serious threat. Farming uses much more water, and pumps are proliferating across India, Bangladesh, and other countries. In addition, rice irrigated with tainted groundwater takes up arsenic and can lower rice production.
Fracking in Pennsylvania
In Pennsylvania, the practice of using hydraulic fracturing to release natural gas from shale grew quickly starting in 2007. In some areas, rates of hospitalization have grown along with it, according to a recent study involving Lamont geochemists Steven Chillrud, Beizhan Yan, and Martin Stute. While the study doesn’t prove a connection, it raises concerns.
The scientists are studying drinking wells in heavily fracked areas of Pennsylvania in hopes of establishing more firmly whether certain substances are being introduced into drinking water through the fracking process. The researchers have also started monitoring air quality within homes near drill sites.
Urban Air Quality
In New York City, Chillrud and colleagues from Columbia’s school for public health are partnering with urban cyclists to test air quality in different neighborhoods of the city and the impact pollution is having on riders. They are outfitting a “Bike Brigade” with sensors to monitor air pollution and the volume of air the cyclists are breathing as they ride. Pairing pollution and volume of air breathed provides a dose measurement that could provide short-term indicators of long-term impacts such as on blood pressure and heart rate.