Longitudinal Renal Function Degradation Among Florida Agricultural Workers

Abstract

Objective: This longitudinal study evaluated renal function and acute kidney injury (AKI) over time in US agricultural workers.

Methods: We followed Florida agricultural workers from January 2020 to August 2022, collecting blood and urine preworkday and postworkday during five visits.

Results: Preworkday estimated glomerular filtration rate function in all participants was lower in summers but relatively consistent over time. In participants who worked almost exclusively in fernery operations (piece-rate compensation), we observed a high incidence of postworkday AKI in 2020 (21%) that increased to 43% by the end of the study. In comparison, 11% of nursery workers (hourly compensation) had AKI, and this rate was fairly stable.

Conclusion: AKI risk over time differs according to the type of agricultural work. Piece rate workers who are incentivized to forgo rest breaks and hydration to earn higher wages demonstrate steadily increasing rates of AKI.

Figure 1.. Heat indices largely comparable in both agricultural settings

At each study visit, the distribution of participants’ work shift heat exposure: mean and max heat index experienced during their work shift and number of hours in which the heat index was above 100°F. Boxplots summarize values for all participants, with the line inside the box representing the median and the symbol inside the box representing the mean. Weather data obtained from the Florida Automated Weather Network (FAWN) monitoring stations. Heat index calculated using Lu and Romps extended heat index algorithm based on ambient temperature and relative humidity.

Figure 2.. Acute kidney injury (AKI) more prevalent among fernery workers

Percentage of participants meeting the criteria for AKI (an increase in serum creatinine from before to after work shift of at least 50% or ≥ 0.3 mg/dL) at each timepoint in each agricultural setting as predicted by generalized linear mixed model containing the following variables: primary work type, timepoint, the interaction of primary work type and timepoint, age, and sex. Error bars reflect 95% Confidence Limits.

Figure 3.. Longitudinal and seasonal dynamics of pre- and post-work estimated kidney function

Average pre- and post-work eGFR calculated from serum creatinine values at each timepoint in each agricultural setting as predicted by linear mixed model containing the following variables: primary work type, timepoint, the interaction of primary work type and timepoint, age, and sex. Error bars reflect 95% Confidence Limits.