On opposite ends of the world, governments are cracking down on pesticides as a potential cause of a mysterious form of kidney disease killing agricultural workers.
In El Salvador, the congress approved a ban earlier this month on 53 agrochemicals. If the law is signed by Salvadorean president Mauricio Funes, the country will join Sri Lanka as the second nation to ban top-selling pesticides for a potential link to kidney disease.
Meanwhile, in India, new research from Harvard University and the state of Andhra Pradesh found local drinking water to be contaminated with high levels of silica — a mineral used in pesticides that has been linked by previous studies to kidney failure.
For more than two years, the International Consortium of Investigative Journalists has examined how a rare type of chronic kidney disease, CKD, is afflicting agricultural workers along Central America’s Pacific Coast, and in Sri Lanka and India. A recent study estimated that the ailment has killed more than 20,000 people in Central America alone, but scientists have yet to definitively uncover the cause of the parallel epidemics.
Following its emergence in the 1990s, the disease was widely ignored by authorities even as it devastated impoverished rural communities. Only now, bolstered by a growing body of scientific research, have governments begun to vigorously search for causes and solutions.
Yet the push to target pesticides is triggering fierce opposition from agribusiness — and concern from some researchers who fear the dramatic pesticide bans could be a distraction from other, potentially stronger scientific evidence linking the malady to the effects of heat stress and dehydration.
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The most sweeping measure contemplated so far: The ban on 53 agrochemicals approved on September 5 by El Salvador’s Legislative Assembly, including leading products such as glyphosate, the active ingredient in Monsanto’s Roundup, and 2-4,D, produced by Dow Chemicals.
The proposed law would prohibit various chemicals that have long been banned in most of the world, but also includes widely used pesticides glyphosate, 2-4,D, paraquat and endosulfan. Salvadorean health officials believe agrochemicals containing toxic heavy metals are the primary cause of the disease.
The move to prohibit major commercial brands has sparked resistance from El Salvador’s Chamber of Agriculture and Agribusiness (CAMAGRO), along with politicians in opposition parties. “As the law is written, the President should veto it,” congress member Mario Ponce, who sought to remove the previously cited four pesticides from the list, told a Salvadorean newspaper. “We would be giving a very severe blow to all of agriculture.”
Monsanto confirmed it sells glyphosate in El Salvador and across Latin America, but said it is confident the product does not cause renal disease. "When glyphosate is used according to label directions there is no concern of harm to the kidneys," said Monsanto spokeswoman Erika Campuzano. "This herbicide has been thoroughly reviewed and registered by regulatory agencies around the world."
Some scientists have raised concerns over the strength of El Salvador's evidence.
A presentation by El Salvador’s government in April found widespread pesticide use and the presence of the heavy metals cadmium and arsenic in the environment in one heavily affected community, but not elsewhere in the country. The government has not produced evidence that particular brands of pesticide contain heavy metals, and glyphosate and 2,4-D are leading worldwide products that are used in countless areas that do not suffer from this distinctive form of kidney disease.
Dr. Carlos Orantes, the director of El Salvador’s national research program into the mysterious disease, said the evidence uncovered is noteworthy, and questions whether opposition to the ban was fueled by business interests.
“Here there is a struggle between toxicity and profitability,” Orantes said.
The pesticide ban has gained the support of the Archbishop of San Salvador, Jose Luis Escobar. “I am very pleased by the fact that they have prohibited these agrochemicals because this will protect human lives,” Escobar said at a press conference in San Salvador. “God willing, the president will approve it and it will become the law of the republic.”
If El Salvador approves the ban, it will follow in the footsteps of Sri Lanka. This spring the South Asian island nation banned several pesticides following a multi-year study by its health ministry and the World Health Organization, which concluded that the heavy metal cadmium had entered the food supply and was a leading cause of CKD. Pesticides and fertilizers are believed to be the source of the contamination, and the chemicals banned in Sri Lanka overlap but do not match fully with those targeted in El Salvador.
On August 27, more than a year after its initial declarations, the Sri Lankan research team published its findings in the medical journal BMC Nephrology. One of their crucial results was a finding of cadmium and pesticide residues in the urine of kidney disease patients. “A significant dose-effect relationship was seen between urine cadmium concentration and CKD stage,” the study found, referring to the stages of kidney decline that indicate the disease’s progression.
Although Sri Lanka’s ban has been officially announced, it has not yet been fully implemented, said Dr. Channa Jayasumana, a Sri Lankan researcher who has been a leading proponent of the pesticide theory. Jayasumana said that the policy’s implementation was facing opposition from agribusiness, and that several of the banned pesticides remain on the market. “We don’t know when they are going to fully implement it,” Jayasumana said.
Perhaps the most striking new clues come from the state of Andhra Pradesh in eastern India.
Preliminary findings by a research team from Harvard University and the Andhra Pradesh state government showed that groundwater in affected villages contained the toxic mineral silica at levels three to five times higher than those encountered in United States. Silica has not emerged as a suspect in the Central American or Sri Lankan epidemics, but a recent study linked occupational exposure to the mineral to increased risk of CKD. Silica is used in some pesticides, including in brands used in India.
Dr. Ajay Singh of Harvard University, one of the study’s directors, said the findings warranted closer examination of silica but were not yet sufficient to draw conclusions. Singh said the research was incomplete because he had not yet seen water tests from unaffected villages in the area to compare levels of silica exposure.
“There’s smoke there but I’m not sure if I’ve detected the fire yet,” he said.
As momentum builds for policies against agrochemicals, some of the scientists who have been studying the disease longest say that, at least in Central America, stronger evidence points to heat stress and dehydration. One study found that sugarcane workers with more physically strenuous jobs suffered significantly higher levels of kidney damage than others at the same company during the course of a single harvest season. Emerging evidence also points toward a possible mechanism for dehydration causing kidney failure, related to the activity of an enzyme in the kidney.
“I do not think that by banning pesticides you will solve the epidemic,” said Dr. Catharina Wesseling of the Program on Work, Environment and Health in Central America (SALTRA), a leader of CKD research in the region.
While pesticides may be a contributing factor, Wesseling said, the most important step for prevention is avoiding dangerous levels of heat stress in the sugar industry.
The two theories are not incompatible: Most scientists agree toxic exposure can create vulnerability, and heat stress can wear away at the kidneys. Wesseling cited the possibility of different chemicals or causes at work in different regions. But she emphasized that proven interventions can prevent heat stress, while the target of sweeping pesticide bans is less clear. “Prevention of heat stress is possible if you have political will,” Wesseling said.
As the scientific hunt for answers continues, workers continue to sicken and die.
Ezekiel Ramirez, a former sugarcane worker in Nicaragua who suffers from CKD, expressed his frustration with the lengthy debate over the disease during a previous ICIJ visit to his community.
“We are worried because time is passing and things are going very slowly,” Ramirez said. “We want this to be fixed now because of the number of people who die each day.”