Popular Herbicide Ingredient Linked to Chronic Kidney Disease Epidemic in Sri Lanka

The active ingredient in Roundup, the world’s most popular herbicide, may play a role in the epidemic levels of chronic kidney disease seen in rural Sri Lanka, a new study suggests.

Published in Environmental Science and Technology Letters, the large field study sampled water sources located in areas with and without high numbers of kidney disease cases. The research team found that the chemical glyphosate, as well as fluoride, vanadium and water hardness within the water wells, were all associated with high local levels of chronic kidney disease.

The mysterious roots of kidney disease clusters

For the past two decades, rural communities in Sri Lanka have been struggling with abnormally high rates of an unusual form of kidney disease. Cases of chronic kidney disease of unknown etiology (CKDu), as it is known, are not linked to any of the commonly known risk factors for kidney disease, including diabetes mellitus, hypertension or glomerular nephritis. 

Since these CKDu cases were first spotted among rice paddy farmers in Sri Lanka’s North Central Province, cases have continued to spread. One recent study suggests that around 9% of children (aged 5–11 years) in the North Central Province are now exhibiting signs of early onset kidney damage. Similar incidences of the mysterious CKDu disease have also emerged among tropical farming communities worldwide.

To improve understanding of these epidemic levels of CKDu, researchers are investigating numerous other environmental factors in search of anything that might be causing kidney problems.

One possible culprit is glyphosate, the active compound used in many popular herbicides. While this compound is normally broken down relatively quickly in the environment, it can form complexes with the metal ions present in hard water – such as magnesium and calcium – which can affect its physical properties. Some research suggests that these glyphosate–metal ion complexes can survive for up to 7 years in water and 22 years in soil environments.

“It was always thought that this chemical would break down very quickly in the environment, but it seems to stick around a lot longer than we expected when it complexes in hard water,” said study author Nishad Jayasundara, the Juli Plant Grainger Assistant Professor of Global Environmental Health at Duke. “We have to consider how glyphosate is interacting with these other elements, and what happens to glyphosate when you take that into your body as a complex.”

While Sri Lanka banned the use of glyphosate-based herbicides for several years, Jayasundara, , who is from Sri Lanka himself, believes that this compound could still be harming the country’s rural communities.

Glyphosate discovered in local wells

For this study, Jayasundara teamed up with research groups led by environmental analytical chemist Lee Ferguson, an associate professor of civil and environmental engineering at Duke, and Mangala De Silva, a professor in the Department of Zoology at the University of Ruhuna, Sri Lanka.

Together, the research team collected water samples from more than 200 wells across 4 geographic regions in Sri Lanka. This included 154 wells located in areas with endemic levels of CKDu cases.

Using liquid chromatography with tandem mass spectrometry (LC-MS/MS), the researchers analyzed each sample for the presence of any glyphosate. Fluoride levels were examined using an in-field ion selective electrode (ISE) meter, while a portable spectrophotometer was used to evaluate water hardness and the presence of calcium and magnesium ions. Additional trace metal analysis was also carried out by inductively coupled plasma-mass spectrometry (ICP-MS).

The team detected glyphosate in 44% of the wells in areas where CKDu is endemic compared to just 8% of the nonendemic wells. Fluoride was found in 99% of endemic wells and 80% of nonendemic wells.

After applying logistic regression to their results, the research team found that elevated levels of glyphosate, fluoride, vanadium and water hardness were all associated with higher local CKDu prevalence.

The consequences of herbicide exposure

Given the issue of glyphosate–metal ion complexing and their observation that both glyphosate levels and water hardness are associated with CKDu prevalence, the researchers say that more attention must be paid to this type of contamination.

The researchers believe that their findings should be also taken as a serious warning of the detrimental effects of this chemical, given its widespread use and its persistent nature in the environment. Ferguson compares the harm of glyphosate contamination to that caused by per- and polyfluoroalkyl substances (PFAS), which are nicknamed “forever chemicals” due to their persistence.

“We think of PFAS as being a drinking water contaminant because it’s mobile and persistent. Now we’re realizing that glyphosate may also be quite persistent in hard water areas,” said Ferguson. “This gives me concerns about exposures here in the United States.”

Glyphosate’s persistence and its association with kidney damage is worrying. In light of their findings, the researchers are urging others to look into the health effects of glyphosate-based herbicides and possible routes of exposure within rural communities.

“We really focused on drinking water here, but it’s possible there are other important routes of exposure—direct contact from agricultural workers spraying the pesticide, or perhaps food or dust,” said Ferguson. “I’d like to see increased study with more emphasis looking at the links among these exposure routes. It still seems like there might be things we’re missing.”

Reference: Ulrich JC, Hoffman K, Gunasekara TDKSC, et al. Glyphosate and fluoride in high-hardness drinking water are positively associated with chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. Environ Sci Technol Lett. 2023;10(10):916-923. doi:10.1021/acs.estlett.3c00504

This article is a rework of a press release issued by Duke University. Material has been edited for length and content.