Heat stress and incidence of acute kidney injury among agricultural workers in Spain

Abstract

BACKGROUND AND AIM Heat stress (HS) is associated with adverse health outcomes among agricultural workers, including acute kidney injury (AKI). The aim on this study was to estimate the incidence of AKI over the course of the work shift and the association with HS among agricultural workers in Spain, where summer temperatures are high and heat waves are expected to be more frequent. METHODS Male agricultural workers were enrolled in the study in two different periods and provinces: summer harvesting season in Alacant (n=43, September 2018) and winter harvesting season in Tarragona (n=52, November 2018 and January 2019). For each participant we estimated exposure to HS during a work shift based on the wet bulb globe temperature (WBGT) index (ISO 7243:2017) and AKI cross-shift incidence, defined as an increase in post-shift serum creatinine by at least 0.3 mg/ dl or at least 1.5 times the pre-shift serum creatinine levels. We collected information on potential confounders. For a subsample of participants (n=54), we measured neutrophil gelatinase-associated lipocalin (NGAL) levels before and after the working shift. We used regression models to assess if heat stress is a risk factors for AKI and increase in NGAL levels. RESULTS Mean WBGT was 24.5 ᵒC (20.2-27.1) during the summer harvesting season and 14.2 ᵒC (8.0-20.7) during the winter harvesting season. Nine percent of workers harvesting during the summer months were exposed to HS. Incidence of AKI was higher during the summer harvesting season (33% versus 4%). HS was associated with cross-shift incidence of AKI [Age adjusted OR (95%CI) =9.6 (1.4, 67.9)]. No differences in NGAL levels were observed between participants exposed to HS. CONCLUSIONS Heat stress is a risk factor for AKI among agricultural workers in Spain even when environmental temperatures are not extremely hot. KEYWORDS Heat stress, Acute kidney injury, Agricultural workers, Mediterranean region