Methods/Statistics
A novel heat exposure metric from work history data: Estimating occupational heat exposure in a low-resourced region Samantha Hall* Samantha Hall Selene Vences Brown Juan José Amador Velasquez Damaris López-Pilarte Maria Argos Luis Carvalho Madeleine K Scammell Daniel R Brooks Jessica H Leibler
Interview-based work histories can be an important tool to estimate individual-level environmental exposure profiles over time, particularly in low-resourced settings where research infrastructure may restrict personal monitoring and satellite datasets may lack spatial resolution. We used work history to estimate longitudinal occupational heat exposure in a prospective study of adolescents at high risk for chronic kidney disease of uncertain etiology in Central America (n=450). We developed a novel categorical heat burden metric that incorporated local knowledge of strenuousness of tasks, radiant and machine-based heat sources, and access to cooling strategies, which we used to classify each self-reported occupational activity and experiences of worksite attendance with an adult in youth as having low (0), moderate (1), or high (2) heat burden. To model exposure duration, we summed months in moderate or high heat paid jobs as full weight and months attending a worksite with an adult as half weight. A dichotomous ever/never variable of occupational heat exposure and the more nuanced exposure duration metric were modeled separately in adjusted regression models to evaluate associations with longitudinal kidney function. We evaluated spatial temperature datasets and residential regions to address effect measure modification by climate trends. More than a quarter of the population (26.7%) had ever worked in moderate or high heat and median exposure duration was 17 months (IQR 24.1). Occupational heat exposure (ever/never) was associated with 0.7% decline/year in estimated glomerular filtration rate in males (95% CI -1.4, -0.1) and 0.9% incline/year in females (95% CI 0.0, 1.7). Work duration was unrelated to kidney outcomes, potentially due to short duration of occupational histories. Our approach suggests detailed work history aligned with climate data assessment can be used to generate cost-effective estimates of occupational heat burden in under-resourced regions.