At the Center for Public Integrity, Sasha Chavkin has the latest news on a mystifying occupational health problem: chronic kidney disease (CKD) in young, previously healthy agricultural workers in Central America, India, and Sri Lanka. Since 2011, the International Consortium of Investigative Journalists has been following CKD in agricultural workers, which researchers estimate has killed 20,000 people in Central America alone.
Chavkin reports that El Salvador's Legislative Assembly has approved a ban on 53 agrochemicals (some of which have been banned for years in most other countries), because health officials there believe heavy-metal-containing pesticides are behind the disease. The country's Chamber of Agriculture and Agribusiness and opposition politicians are urging President Mauricio Funes to veto the legislation. If President Funes approves the ban, El Salvador will be following in Sri Lanka's footsteps, Chavkin explains:
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.
Researchers from Harvard University and the state government of Andhra Pradesh in India have found groundwater in local villages affected by CKD to contain high levels of silica, which is used in some pesticides. Chavkin notes, "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." Meanwhile, some researchers suggest that factors other than pesticide exposures are involved:
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.
With young agricultural workers dying by the thousands, there's a sense of urgency to uncover the mechanisms behind this type of CKD and adopt policies to prevent it from claiming more workers' lives.
In other news:
Fuel Fix: A study published in the American Journal of Medicine compares the blood of 117 workers who cleaned beaches and marshes following the 2010 BP/ Deepwater Horizon oil spill in the Gulf of Mexico to 130 patients not involved in cleanup. Researchers found that the cleanup workers have "significantly altered blood profiles that put them at increased risk of developing liver cancer, leukemia and other disorders."
Scientific American: The Occupational Safety and Health Administration hasn't updated its general workplace lead-exposure standards for 35 years, despite recommendations that it reduce permissible exposure levels. California's OSHA isn't waiting for a new federal standard, but is working to strengthen its regulations for on-the-job lead exposure.
Occupational Safety and Health Administration: Following the June death of a worker from heat stress, OSHA has cited BFI Waste Services of Texas LP, doing business as Republic Services Inc., and their temporary labor provider Recana Solutions LLC for seven violations with proposed penalties totaling $33,000.
Los Angeles Times editorial: California seems likely to adopt an increase to the minimum wage. The benefits of the increase outweigh the downsides, and "no Californian who works full time should be stuck with poverty wages."
Al Jazeera: A coal mine collapse trapped 57 workers in a coal mine in Afghanistan's Samangan province, and rescue workers lacking necessary equipment dug with their bare hands to try and reach the miners. (The latest death toll stands at 27.) The mining sector is often considered one of the country's last great economic hopes, but is extremely hazardous -- and in a country with one of the highest corruption perception index scores from Transparency International, it's unlikely that mining income will translate to meaningful impact for Afghanistan's low-income population
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