Heat strain, volume depletion and kidney function in California agricultural workers

Abstract

Background Agricultural work can expose workers to increased risk of heat strain and volume depletion due to repeated exposures to high ambient temperatures, arduous physical exertion and limited rehydration. These risk factors may result in acute kidney injury (AKI). Methods We estimated AKI cumulative incidence in a convenience sample of 283 agricultural workers based on elevations of serum creatinine between preshift and postshift blood samples. Heat strain was assessed based on changes in core body temperature and heart rate. Volume depletion was assessed using changes in body mass over the work shift. Logistic regression models were used to estimate the associations of AKI with traditional risk factors (age, diabetes, hypertension and history of kidney disease) as well as with occupational risk factors (years in farm work, method of payment and farm task). Results 35 participants were characterised with incident AKI over the course of a work shift (12.3%). Workers who experienced heat strain had increased adjusted odds of AKI (1.34, 95% CI 1.04 to 1.74). Piece rate work was associated with 4.24 odds of AKI (95% CI 1.56 to 11.52). Females paid by the piece had 102.81 adjusted odds of AKI (95% CI 7.32 to 1443.20). Discussion Heat strain and piece rate work are associated with incident AKI after a single shift of agricultural work, though gender differences exist. Modifications to payment structures may help prevent AKI.

Acute kidney injury and workload in a sample of California agricultural workers

“…It is conceivable that similar damage induces AKI in agricultural workers. In previous work, we found an increased risk of AKI among workers who were paid by the piece, that is, by the amount they harvest . Workers who are paid by the piece tend to work harder and faster than those paid by the hour because they can make more money, suggesting that they experience higher workload and thus, a higher risk of AKI.…”

“…Participants were recruited as part of the California Heat Illness Prevention Study, and methods have been described elsewhere . Briefly, eligible participants for this study were adults age 18 or older, working in the fields for at least 6 hours per day, understood Spanish or English, and had no impediments to swallowing an ingestible sensor.…”

“…Finally, we included two‐time variables in our analyses: one to account for the week of data collection to estimate if AKI occurred more frequently in workers who were sampled later in the summer or who had worked for a longer amount of time over the summer; and a second variable of year of data collection (year 1 vs year 2) to estimate differences by year that were not assessed by measured variables (eg, shade availability, length of breaks, work team compositions, etc). Because we included participants who were part of our first analysis of AKI, we included the year variable to determine if there were differences between the workers in the 2 years.…”

Climate Change and the Emergent Epidemic of CKD from Heat Stress in Rural Communities: The Case for Heat Stress Nephropathy

“…There have also been reports that farm workers, most of whom are migrants, may be developing acute kidney disease and CKD at higher rates than expected in the Central Valley of California (92,93). One recent study linked hospitalizations for dehydration and AKI with the onset of heat waves in the Central Valley and other hot regions in California (94).…”

Climate Change and the Kidney

“…Acute kidney injury is now being reported throughout the world in hot agricultural communities including India (Andhra Pradesh), Sri Lanka (north central province), Mexico (Vera Cruz), central Florida, and the Central Valley of California [56][57][58]. In many of these areas, epidemics of CKD are also being reported [59][60][61].…”