Heat and toxic exposures could harm kidneys in agricultural workers, findings indicate

Heat and constant exposure to toxic metals and metalloids can be a dangerous combination for the kidneys of agricultural workers, as revealed by a recent study conducted at the University of Arizona.

The research at the U of A Mel and Enid Zuckerman College of Public Health focused on a group of farm workers during a summer season, finding that elevated levels of arsenic, cadmium, and chromium in the urine were associated with increased signs of kidney injury. Additionally, higher uranium levels in the urine were linked to decreased kidney function. The extreme summer heat of the Sonoran Desert exacerbated the impact of arsenic and cadmium on kidney health.

The study underscores the importance of addressing potential health risks for those working in hot environments and highlights the need for stricter workplace policies to mitigate these risks.

A team led by postdoctoral fellow Rietta Wagoner, former doctoral student Nicolas Lopez-Galvez (now at San Diego State University), and Melissa Furlong, assistant professor of environmental health sciences, published their findings in Environmental Research.

“We are observing a rise in kidney disease among young individuals who do not exhibit typical risk factors, particularly in hotter regions,” Wagoner commented.

“There is evidence indicating that heat, pesticides, and metal exposures each play a role, with heat exacerbating potentially toxic exposures. While each factor has been studied independently, there is limited research examining their combined effects. This study aims to address these questions.”

In 2019, Wagoner, Lopez-Galvez, and their team studied 77 agricultural workers who traveled seasonally from southern Mexico to a grape farm near the Arizona-Sonora border. The workers arrived in February and March, at the start of the grape season, and remained until the end of summer. Twenty office workers also participated as a control group.

The researchers conducted surveys, collected daily urine and blood samples, and monitored heat stress twice daily using inner ear temperatures and heart rates during work hours and rest breaks. Estimates of kidney function were based on age, creatinine levels in blood samples, and a marker of kidney injury known as urinary neutrophil gelatinase-associated lipocalin. The study also assessed metal exposure in urine and hydration levels.

Wagoner and the team examined exposure to potential toxic metals like arsenic, cadmium, and uranium, while considering the impact of extreme heat on the workers’ bodies.

“When we analyzed heat in conjunction with metals and metalloids, we found that heat notably intensified the effects of arsenic and cadmium on kidney health,” Wagoner explained. “In essence, the combined effects were more severe.”

Prevention is crucial when it comes to heat-related illnesses and kidney injury, according to Wagoner.

“We recommend implementing mandatory periodic breaks and rest periods throughout the workday,” she advised. “Provide access to water, electrolyte replacements, and ensure restroom facilities are easily accessible. Additionally, allow workers time to acclimate to the conditions.”

Understanding the potential sources of metal exposures is also vital, Wagoner emphasized. In the region where the study was conducted, workers consume well water containing uranium and arsenic from the soil. Cadmium can be found in cigarettes and alcohol, while lead may be present in pottery.

“By implementing preventive measures early on,” Wagoner added, “we can prevent long-term issues from arising.”