Sugarcane Workweek Study: Risk Factors for Daily Changes in Creatinine

Abstract

Introduction: Agricultural workers laboring in thermally stressful environments are at increased risk for kidney injury and chronic kidney disease of unknown origin (CKDu), and their environmental and occupational exposures have been considered to be important risk factors. This study examined the effects of repeated kidney stress from the simultaneous strain of work and other factors experienced by workers in Guatemala during a typical workweek.

Methods: We collected data from 107 sugarcane workers across 7 consecutive work shifts. Data included information on daily occupational, meteorological, environmental, and lifestyle factors. We used multivariable linear mixed models to evaluate associations of these factors with percent change in creatinine.

Results: We observed that increasing wet bulb globe temperature (β = 2.5%, 95% confidence interval [CI] = 0.3%, 4.7%) and increasing diastolic blood pressure (β = 6.2%, 95% CI = 0.9%, 11.6%) were associated with increases in creatinine across the shift, whereas consumption of water from chlorinated dormitory tanks as compared to artesian well water (β = -17.5%, 95% CI = -29.6%, -5.4%) and increasing number of rest breaks (β = -5.8%, 95% CI = -9.0%, -2.6%) were found to be protective against increases in creatinine. Workers reporting drinking tank water had lower concentrations of urine creatinine-corrected arsenic, lead, uranium, and glyphosate compared to workers reporting the use of well water or municipal water.

Conclusion: These results reinforce the need to focus on preventive actions that reduce kidney injury among this worker population, including strategies to reduce heat stress, managing blood pressure, and examining water sources of workers for nephrotoxic contaminants.

Keywords: agriculture; heat stress; kidney injury; worker health.

Graphical abstract

Figure 1

Summary of data collection over the 2017 to 2018 sugarcane harvest used in the present study. BP, blood pressure; eGFR, estimated glomerular filtration rate; POC Creatinine, point-of-care capillary creatinine; USG, urinary specific gravity; WBGT, Wet Bulb Globe Temperature.

Figure 2

Distribution of percent change in creatinine across study workdays. A positive percent change indicates a decline in kidney function from pre- to post-shift (N = 107 sugarcane cutters).

Figure 3

Day 2 urinary metals and glyphosate concentrations (corrected for urine creatinine) by morning drinking water source. ∗Significance at p < 0.05 based on analysis of variance.