Introduction

Launching its deepest review yet into a mysterious kidney disease striking Central America, the U.S. Centers for Disease Control and Prevention is organizing three studies exploring the causes of an ailment afflicting thousands of sugarcane workers.

The research will be funded by $1.7 million in contributions from the Central American sugar industry — a setup raising concerns with some about how fully the studies will address the industry’s role in the outbreak. The CDC said it has protocols in place to prevent undue influence.

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, as well as in Sri Lanka and India. A recent study estimated that the ailment has killed more than 20,000 people in Central America alone.

Most scientists suspect the disease is caused by a combination of factors including chronic dehydration from hard labor in tropical heat and exposure to toxins such as pesticides. Still, experts have yet to fully uncover the origins of a malady that has devastated agricultural communities across Central America.

One village of sugarcane workers near Chichigalpa, Nicaragua, called La Isla, or “The Island,” has lost so many men to the disease it is now known as the “Island of the Widows.”

Ailing Nicaraguan sugarcane workers have staged angry protests, demanding compensation and medical care from sugar companies. Last month, Juan de Dios Cortez, a 48-year-old cane worker, was gunned down by police who forcibly broke up a protest of sick former workers blocking the entrance to a sugar mill in Chichigalpa. Three police officers who fired on the demonstrators were subsequently discharged following an internal investigation by the Nicaraguan National Police.

The bitter dispute over the role of work practices in CKD has fueled growing tensions among the scientists.

Some feel more proof is warranted before conclusions are drawn; others say clear evidence already shows that dehydration experienced on the job is a basic cause of the disease, creating a moral obligation to act.

The question of whether the disease is linked to occupational hazards carries high stakes. That designation could mean improved medical benefits and possible compensation for workers, and the risk of major liability for the industry.

The industry maintains it is not at fault, and said it is open to the review.

“We are fully convinced that there is no direct relationship between CKD and the activities conducted in the sugarcane industry,” said Mario Amador, general manager of Nicaragua’s National Committee of Sugar Producers, one of the groups funding the CDC studies. “A sign of our good faith and our conviction about this is the support we give to scientific studies.”

The team conducting the CDC and industry-backed study will be led by Boston University epidemiologist Daniel Brooks. He previously conducted a study of CKD in Chichigalpa that was organized by the World Bank and funded by the sugar industry as part of a mediation process triggered by a community complaint.

Brooks’ research pointed toward dehydration as a likely culprit, but he has been cautious in describing his results. “The Boston University team believes that the CKD epidemic is caused by a combination of factors,” Brooks said in an email. “Results to date suggest that one or more of these causes are occupational, and more research is needed to identify the specific factors.”

The CDC said in a statement that “we don’t know” if labor practices are to blame.

Brooks and his team will conduct three new studies in partnership with the CDC. One will examine the role of occupational factors in the disease, a second the possibility of a genetic component, and a third the process of early-onset kidney damage among adolescents in the affected areas.

The conflict of interest question

Funding for the studies will be routed through the CDC Foundation, a nonprofit organization affiliated with the CDC that raises outside funding to support research.

The occupational study will be backed by $1.05 million from the Sugar Producers of the Central American Isthmus, and the genetics and adolescent studies will be funded by $675,000 from the National Committee of Sugar Producers of Nicaragua.

Amid the larger scientific debate over the causes of CKD, some have raised concerns about the industry’s financial support for the CDC’s research.

Catharina Wesseling, an epidemiologist who chairs the scientific group Consortium for the Epidemic of Nephropathy in Central America and Mexico (CENCAM), expressed concern that the grants were not awarded through an open bidding process. Instead, according to the CDC Foundation, Boston University approached the CDC with a proposal, and funding was then obtained from the sugar industry.

“It’s not the correct way to do it for me,” Wesseling said. “There’s still an indirect link.”

The CDC Foundation and Boston University said Brooks and the CDC would control all aspects of the study’s design and execution, that findings would be published regardless of outcome, and that the study team would create a publicly available website with updates on the status of the research. Industry personnel will have no role in the study team.

“CDC is committed to helping to find the etiology of the illness,” said Dr. Reina Turcios-Ruiz, an epidemiologist with the CDC. “We are actively working to guard scientific integrity of what we find.”

Medical ethics experts consulted by ICIJ said that while the arrangement did pose the risk of conflict of interest, public-private partnerships were important tools for supporting vital research that might not obtain funding otherwise.

“The real question is how we can best manage conflict to ensure objective science,” said Dr. Cary Gross, a professor at the Yale School of Medicine and its Program for Biomedical Ethics.

The “occupational illness” divide

And the larger question remains: What has triggered the outbreak?

Some researchers in the region say evidence for the dehydration hypothesis is overwhelming and argue that, even if other factors are involved, its role is clear enough to demand immediate workplace interventions. “The best evidence now, and it is very, very strong evidence, is dehydration,” said Wesseling. “That is evidently an occupational disease.”

Recent studies by scientists in CENCAM identified a biological mechanism in which dehydration produced CKD in lab rats, through the activity of an enzyme in the kidney. A previous study by Brooks showed that sugarcane workers in strenuous jobs such as cutting cane suffered significantly more kidney damage over the course of a single harvest season than other workers.

Last week, the nonprofit organizations Solidaridad and La Isla Foundation, which supported the CENCAM research, received a multimillion-dollar grant from the Dutch National Postcode Lottery to fund a new series of studies.

The research will focus on dehydration interventions such as more water, rest and shade for workers, said Jason Glaser, the director of La Isla Foundation. The studies will also explore how dehydration may interact with environmental toxins to sicken workers. “If you want to save lives, you need to focus on occupation and you need to get real,” said Glaser, who has been an outspoken critic of the sugar industry.

The evidence for dehydration may be growing, but scientific debate still churns. Government-backed studies in El Salvador and Sri Lanka have found pesticides and fertilizers to be the primary causes of the ailment, and officials in those countries are seeking to ban leading brands of agrochemicals from affected areas.

While the theories are not incompatible — dehydration and toxic exposure could be working together — the mysterious ailment has become a political Rorschach test.

The left-leaning El Salvadoran government, backed by Cuban doctors, blames pesticides imported by Western multinationals. The scientists and NGOs involved in groups such as CENCAM, many of them from Europe and United States, focus on brutal working conditions in the sugar industry.

For its part, the industry emphasizes the uncertainties in the science, and has long attributed the disease to alcohol abuse and poor health habits among its workers.

Editor’s note: This story has been updated to reflect how the Solidaridad/La Isla Foundation studies will explore environmental toxins as well as dehydration as a potential cause for CKD.