New Study Shows Heat Stress Protections Prevent Kidney Injury Among Farmworkers—and Save Lives

The lack of a federal standard to protect agricultural workers from heat stress endangers the health and lives of farmworkers across the U.S. Heat stress is a frequent risk to farmworkers, who often spend long periods doing physically-demanding work in high temperatures and humidity. Beyond the risk of hyperthermia –or heat stroke—agricultural workers laboring in these conditions also face the possibility of developing a disabling and potentially fatal form of chronic kidney disease (CKD).  An increasing number of scientific studies point to heat stress and dehydration as the potential causes of CKD among farmworkers.[1] An international group of researchers conducting a study of sugar cane workers in Chichigalpa, Nicaragua –an area with high CKD rates—recently found that providing basic protections to these farmworkers, such as access to drinking water, and rest breaks in shaded areas, drastically reduced rates of incident kidney injury (IKI). IKI, a measure of kidney injury over a span of time –the November-April harvest period, in this study—is an indicator of CKD risk. Burned cane cutters, who had the highest workload among the farmworkers studied and were at highest risk of heat stress, had a 74% decrease in rates of IKI, from 27% of workers to 7%.[2]

Heat stress While an epidemic of CKD has been affecting farmworkers in Central America for decades,[3] it is only in the last few years that its occurrence in the U.S. has gained attention.[4] Rates of CKD in the U.S. are unknown, but one California study found a 12% rate of acute kidney injury (AKI) in agricultural workers who were evaluated over a one-workday period,[5] while a longer study in Florida that assessed workers over the course of 555 workdays found a rate of 33%.[6] Such alarming rates of AKI –which is significantly associated with CKD[7]—are likely to worsen due to climate change. The current trend toward higher temperatures across the U.S. is expected to accelerate,[8] and with it the health risks posed by extreme heat to outdoor workers.

In the U.S., only California, Washington and Minnesota have state standards to protect workers from heat stress. To address the dangerous lack of basic heat stress protections in much of the country, Representatives Judy Chu (CA-27) and Raul Grijalva (AZ-3) have introduced the Asuncion Valdivia Heat Illness and Fatality Prevention Act, H.R.3668, which requires the Department of Labor to issue an enforceable standard to prevent worker exposure to excessive heat in the workplace. This bill, which Farmworker Justice strongly supports, is named after a farmworker who tragically died from heat stress. The bill would require worker access to water, rest periods and shade; limit the amount of time workers could be required to work in excessive heat; require employers to train employees on heat illness prevention; and offer protections to whistleblowers.

Rep. Chu, who has an extensive record of advancing farmworker protections through her work in the California State Assembly and in Congress, recently discussed this bill in an interview with FJ President Bruce Goldstein. During the interview, which was part of our 17-episode series “The State of Farmworkers in the COVID-19 Era,” Rep. Chu said of the protections mandated in the bill: “All this should be common sense, but without a federal requirement on employers, more and more workers will die completely preventable deaths.” H.R.3668 is modeled after a similar bill Rep. Chu successfully championed in the California Assembly, which led to California becoming the first state in the U.S. to adopt a heat stress standard that protected farmworkers.

FJ will continue working to achieve passage of this important piece of legislation, so that long-overdue heat stress protections are put in place. Farmworkers perform one of the most arduous and dangerous jobs, and they should not have to fight their employers for access to something so basic as a sufficient amount of water, rest and shade.


[1] Laws RL, Brooks DR, Amador JJ , Weiner DE, Kaufman JS, Ramirez-Rubio O, Riefkohl A, Scammell MK, López-Pilarte D, Sánchez JM, Parikh CR, McClean MD.  Biomarkers of Kidney Injury Among Nicaraguan Sugarcane Workers. Am J Kidney Dis 2016;67:209–17. doi:10.1053/j.ajkd.2015.08.022.

Nerbass FB, Pecoits-Filho R, Clark WF, Sontrop JM, McIntyre CW, Moist L. Occupational Heat Stress and Kidney Health: From Farms to Factories. Kidney Int Rep. 2017 Aug 31;2(6):998-1008. doi: 10.1016/j.ekir.2017.08.012.

[2] Glaser J, Hansson E, Weiss I, Wesseling C, Jakobsson K, Ekström U,  Apelqvist J, Lucas R, Mongel EA, Perazal S, Hogstedtl C, Wegman DH. Preventing kidney injury among sugarcane workers: promising evidence from enhanced workplace interventions. Occup Environ Med Epub ahead of print: May 13, 2020. doi: 10.1136/oemed-2020-106406.

[3] De Ferrari R. The Silent Massacre: Chronic Kidney Disease in Central America’s Sugarcane Workers. Panoramas, November 14, 2017. Available at: Last accessed May 20, 2020.

[4] Fernandez E. On the trail of a deadly disease that cuts down farmworkers in their prime. Bloomberg Businessweek 2018; Sep 25. Available at:

Kelly D. Chronic kidney disease epidemic in agricultural workers: High heat, toxins. ScienceDaily, May 8, 2019. Available at: Last accessed May 20,2020

[5] Moyce S, Mitchell D, Schenker M. Heat strain, volume depletion and kidney function in California agricultural workers. Occup Environ Med. 2017 Jun; 74(6):402-409. doi: 10.1136/oemed-2016-103848.

[6] Mix J, Elon L, Vi Thien Mac V, Flocks J, Economos E, Tovar-Aguilar AJ, Stover Hertzberg V, McCauley, LA. Hydration Status, Kidney Function, and Kidney Injury in Florida Agricultural Workers. J Occup Environ Med. 2018 May;60(5):e253-e260. doi: 10.1097/JOM.0000000000001261.

[7] Hsu RK, Hsu C. The role of acute kidney injury in chronic kidney disease. Semin Nephrol. 2016 Jul; 36(4): 283–292. doi: 10.1016/j.semnephrol.2016.05.005.

[8] U.S. Global Change Research Program. 2014 National Climate Assessment. Available at: Last accessed May 21, 2020.