Experimenting on a grand scale: Environmental chemist Paul Capel studies glyphosate’s occurrence in the environment

Environmental chemist and Water Resources Science graduate program faculty member Paul Capel has spent more than a decade researching what happens to glyphosate after it’s applied to agricultural fields. An adjunct associate professor in the University’s Department of Civil Engineering and a research team leader with the U.S. Geological Survey’s National Water-Quality Assessment Program, Capel has focused on Iowa, Indiana and Mississippi where much of the landscape is devoted to the production of corn, soybeans, cotton and alfalfa.

“We’ve hitched much of our agricultural wagon to the use of glyphosate,” says Capel, “My perspective is that we’re with glyphosate now where we were in the early days of DDT use in the 1950 and 1960s—we’re conducting a big experiment with the environment.”

Glyphosate acts as a growth hormone, rather than a poison, interfering with a plant’s EPSP synthase enzyme needed for growth. While glyphosate is not a carcinogen and is considered non-toxic to animals, there’s evidence that it can have subtle adverse effects on the environment such as causing nutrient deficiencies in plants. At one time, it was thought that weeds could not develop a resistance to glyphosate, but currently 28 species of weeds have done so.

From an agronomical perspective, glyphosate has been a boon, says Capel. A broad-spectrum weed controller developed in 1970, glyphosate has revolutionized agriculture and given rise to an entire industry of “Roundup Ready” crops. In the 1990s, agricultural seed companies began to genetically engineer crops to be resistant to glyphosate. The U.S. agricultural usage of glyphosate increased from less than 11,000 metric tons in 1992, to more than 99,000 metric tons in 2009. A whopping 90 percent or more of the U.S. corn, soybean and cotton crops are now grown from glyphosate resistant engineered seeds.

Glyphosate’s molecular structure is difficult to detect in the environment, making studies of its occurrence and effects time-consuming and expensive. Capel and his research partners are the first to have sampled and analyzed glyphosate in rain and air, as wells as streams and groundwater, in Iowa, Indiana and Mississippi throughout the growing season. His research shows that glyphosate is routinely observed in streams, air and rain near these agricultural areas through the growing season and beyond.

"Though glyphosate is the mostly widely used herbicide in the world, we know very little about its long term effects to the environment," says Capel. “Our studies provide the foundation of what questions we should be asking and what toxicologists and epidemiologists will be looking for down the road.”

Paul Capel and Erik Smith with rain samplerPaul Capel (right) and Erik Smith, a graduate of the Water 
Resources Sciences Graduate Program, set up a rain sampler in Iowa.
Photo credit: Paul Capel