Climate change
Monday 6 October 2025, 16.00 – 17.30 Polar
Chairs: Sara DeMatteis, Mary Njoroge
A guide for investigations of heat stress and kidney function in occupational settings in hot climates
Kristina Jakobsson (presenter)
Michael Silva-Peñaherrera, Ilana Weiss, Esteban Arias-Monge, Ulf Ekström, Jason Glaser, Erik Hansson, Rebekah AI Lucas, Felipe Pacheco-Zenteno, Sandra Peraza, Bethany D Skinner, Catharina Wesseling, David H Wegman, and the La Isla Research Network
Abstract
Objective: To develop a comprehensive, step-by-step guide for conducting successful field studies on occupational heat stress and kidney function in hot climates, specifically tailored to low-resource settings, in the context of the developing world.
Material and Methods: This guide was developed through synthesis of extensive field experience and critical review of a broad range of literature. Key components of successful workplace-based investigations were identified. The process focused on practical challenges and methodological needs, from early planning to reporting results.
Results: The guide emphasizes initiating research with full stakeholder engagement and contextual site visits. A clear research question and study population must be defined. It outlines, workplace visits providing contextual understanding and interaction with stakeholders before determining priority study groups and for logistical planning for field data collectionLocal resources for health care and laboratory analysis need to be specified and considered. The guide provides recommendations for assessing environmental heat, workload, heat strain, hydration, and a selection of health outcomes as well as questionnaire development. Detailed checklists and basic questionnaires are provided.Finally, an approach to analysis and report writing is emphasized.
Conclusion: This guide offers a structured approach to occupational heat stress and kidney health research, enhancing comparability across settings and strengthening evidence to inform effective interventions for prevention of workplace heat stress and related health risks. Acknowledgements We acknowledge the La Isla Network´s field team. Without their experiences on the ground and the multidisciplinary expertise, this protocol paper could not have been written. A Belmont Forum grant, PREP provided external funding. In-kind funding was also obtained from the University of Gothenburg and Lund University, Sweden, the University of Birmingham, UK, and from La Isla Network.
Heat stress in European agriculture – a growing challenge to worker health
Bethany Skinner (presenter)
Michael Silva-Peñaherrera, Esteban Arias-Monge, Kristina Jakobsson, Matthijs Nieuwenhuis, Jason Glaser, Felipe Pacheco-Zenteno, Ilana Weiss, Catharina Wesseling
Abstract
Objective: To examine the workplace practices and physiological workload of agricultural workers in Spain to guide future interventions to protect worker health.
Materials and methods: Worker assessments were made across nine agricultural job tasks (seven outdoor and two indoor) in Spain. Preventative heat exposure strategies were documented through direct observation and photographs. Knowledge, Attitudes, Practices, and Policies (KAPP) were assessed via worker questionnaires (n=56) and management interviews (n=12). Physiological workload was evaluated across job tasks (n=69) via continuous heart rate (HR) measurements across a work shift and used to calculate time in relative HR zones, estimated core temperature (ECTemp), and the proportion of the work shift spent at an ECTemp >38 °C (above which heat strain is considered present). Local wet-bulb globe temperatures (WBGT) were recorded.
Results: KAPP assessments revealed strong organisational support for occupational safety and health, with documented heat stress prevention policies. However, critical gaps were identified between policy and implementation. Rest breaks (totalling 6%-to-15% of work shift), access to shade, hydration levels (estimated 2.3 ± 2.0 L/day), and solar radiation personal protective equipment (PPE) insufficiently protected workers from heat stress. Managers demonstrated good knowledge of heat-related health risks, while workers showed limited understanding but a willingness to adopt preventative measures. Workers spent most of their shift working at a light-moderate (37 ± 22% of their shift) to moderate (14 ± 20%) workload intensity while maximum ECTemp, on average, remained below 38 °C irrespective of the job task (37.6 ± 0.4 °C). However, several workers worked harder than the group average, spending prolonged periods at an ECTemp >38 °C (i.e.,>60% of their shift) and exposed to heat strain.
Conclusion: Improvements in the implementation of heat stress prevention strategies are needed to adequately protect all workers. Recommendations include improving hydration practices, enforcing mandatory rest schedules, and enhancing PPE standards and training.
Impact of occupational heat stress on symptoms, physiological strain, and productivity in Thai sugarcane workers
Tadpong Tantipanjaporn (presenter)
Andrew Povey, Holly A. Shiels, Matthew Gittins, and Martie van Tongeren
Abstract
With continued global warming, the effects of elevated temperatures on agricultural workers’ health and well-being are a particular concern, especially in countries like Thailand. The objective of this study was to evaluate the effects of heat stress on heat-related symptoms, physiological strain, and productivity among Thai sugarcane workers. A total of 295 sugarcane workers from Nakhon Sawan Province, Thailand, were recruited. For each sugarcane worker, full-shift Wet Bulb Globe Temperature (WBGT) measurements were carried out during one harvesting day, either in the hot or cool season. The results of these measurements were adjusted for clothing factors, resulting in a time-weighted average effective WBGT (WBGTeff). Physiological outcomes, including heart rate, blood pressure, and body temperature, were measured twice (pre- and post-shift) on the same day. Statistical analyses examined the effects of heat stress on the outcomes, adjusting for relevant confounders. The mean WBGTeff was 31.30±2.80 °C, ranging from 22.90 to 35.40 °C. The adjusted relative risk (RR) for the number of heat-related symptoms was 1.10 (95% CI: 1.08, 1.13) for a 1°C increase in WBGTeff. WBGTeff was not significantly associated with either post-shift systolic or diastolic blood pressure but was with post-shift results of both heart rate [B (95% CI): 0.61 (0.24, 0.98)] and body temperature [0.02 (0.002, 0.03)], adjusting for pre-shift results and confounders. Finally, an increase in WBGTeff significantly reduced the number of sugarcane stalks harvested per hour [-11.96 (-19.01, -4.92)], adjusting for confounders. The findings highlight heat-induced health issues and productivity loss. As global temperature rises, and heat stress accordingly increases, this study emphasizes the impact of heat stress in agricultural populations. Interventions to reduce heat stress are urgently needed.
Kidney injury in Nicaraguan sugarcane workers – prevention and consequences
Kristina Jakobsson (presenter)
Erik Hansson, Jason R. Glaser, Ilana Weiss, Esteban Arias-Monge, Felipe Pacheco-Zenteno, Nathan H. Raines, Michael Silva-Peñaherrer, Javier Vasquez, Zoey E. Castellón, Scarlette Poveda, Fatima I. Cerda-Granados, William Jose Martinez-Cuadra, Daniel Smith, Paul Callejas, Denis Chavarría, Rebekah A.I. Lucas, Ulf Ekström, Catharina Wesseling, David H. Wegman
Abstract
Objectives: To study the effect of enhancing rest-shade-hydration-hygiene (RSHH) interventions on kidney injury and inflammation biomarkers, and rates of clinical acute kidney injury (AKI) in Nicaraguan sugarcane workers with a very high rate of chronic kidney disease of non-traditional origin (CKDnt), and the long-term estimated glomerular filtration rate (eGFR) trends in workers with kidney injury.
Methods: We analyzed serum creatinine and C-reactive protein (CRP) and leukocyturia from samples obtained before and at the end of four harvest seasons (H1-4). An increase in creatinine ≥0.30 mg/dL over the harvest was considered incident kidney injury (IKI). Clinically diagnosed AKI were obtained from medical records. Each season the RSHH intervention included progressively longer and more frequent rest periods with improved access to shade and hydration, implementation monitoring, and health outcome assessments. Changes in eGFR during 2-4 years of followup were calculated for workers with and without kidney injury respectively.
Results: 1,044 workers were followed for 1,938 person-harvests. Among burned cane cutters, the workgroup with with the highest workload and worst outcomes initially, rates of IKI (21% in H1 to 1% in H4, p<0.01), AKI (20/1000 worker-months to 8/1000 worker-months, p<0.01), end-harvest leukocyturia (26% to 1%, p<0.01), and cross-harvest CRP rises (median 1.75 fold-increase in H1 to 1.00 in H4, p<0.01) decreased. Workers experiencing kidney injury had lost approximately 10 ml/min/1.73m2 more eGFR during follow-up than workers who had not experienced kidney injury.
Conclusion: A structured RSHH intervention supported by implementation monitoring and commitment from workplace management reduced AKI rates and improved markers of kidney injury and inflammation among heat-stressed workers at high risk of CKDnt. The findings support a causal relationship between heat stress, kidney injury and ultimately CKDnt.
Occupational factors associated with impaired kidney function in a Taiwanese agricultural population
Chung-Yen Chen (presenter)
Ping-Ju Hsieh
Abstract
Objective: Heat stress and nephrotoxic pesticides have been proposed as factors impairing farmers’ renal function. This study aimed to assess the association between agricultural work characteristics and renal function among farmers in Taiwan.
Material and Methods: We analyzed data from participants in the ongoing Cohort for Occupational Health among Farmers in Taiwan (COH-FIT). Demographic data, work conditions, health behaviors, and medical histories were collected via structured questionnaires. Work tasks were classified as outdoor, screenhouse/greenhouse, or indoor, with daily durations reported. Body composition, blood, and urine samples were collected during health examinations. Impaired renal function was defined as blood urea nitrogen (BUN) > 25 mg/dL, serum creatinine (Cre) > 1.5 mg/dL, estimated glomerular filtration rate (eGFR) 0.99 mg/L. Student’s t-tests compared renal function across work groups; multivariate logistic regression identified associated factors.
Results: Among 635 participants, 546 (86.0%) engaged in outdoor work, 158 (24.9%) in screenhouse/greenhouse work, and 147 (23.2%) in indoor work. Male farmers and those with junior high school education or below had significantly higher BUN, Cre, and cystatin C levels. Screenhouse/greenhouse and indoor workers showed significantly lower renal markers. Longer outdoor work hours in summer were associated with elevated BUN (OR 1.32; 95% CI: 1.09–1.60) and Cre (OR 1.36; 95% CI: 1.00–1.85). Indoor work showed a non-significant trend toward lower renal risk. Pesticide use was not significantly associated with renal outcomes. Age consistently predicted worse renal function, while diabetes, hypertension, hyperuricemia, and smoking were linked to select outcomes.
Conclusion: Prolonged outdoor agricultural work and heat stress pose important renal health risks, especially amid global warming. Adjusting work schedules, ensuring hydration, and protecting aging farmers and those with preexisting conditions are critical. Longitudinal follow-up will provide further insight into the long-term occupational impacts on renal health.
Workload, age, sex, and core body temperature as predictors of short term kidney injury in Nicaraguan sugarcane workers
Leah Martin (presenter)
Bethany D Skinner , Rebekah AI Lucas , Catharina Wesseling , Michael Silva-Peñaherrera , Kristina Jakobsson , Ilana Weiss , Esteban Arias-Monge , Jason Glaser , Erik Hansson , David H Wegman
Abstract
Objective: To examine workload related and other factors as predictors of change in serum creatinine (SCr) and acute kidney injury (AKI) among Nicaraguan sugarcane workers.
Material and Methods: During the 2023–2024 sugarcane harvest, demographic data and SCr levels were collected pre- and post-shift from 300 workers across 12 job types. AKI was defined as an increase in SCr ≥0.3 mg/dL across the shift. In a subset of 140 workers from 3 jobs, heart rate (HR) was collected and core temperature estimated (eCT). Workload intensity was classified by %HRmax using data collected over several years. Linear mixed-effects models assessed associations between log-transformed post-shift SCr, adjusting for time-by-workload and time-by-age interactions and examining eCT. Logistic regression estimated the odds of AKI in SCr models, while penalized logistic regression assessed odds of AKI with eCT, adjusting for age, sex, and workload category. Beta coefficients were exponentiated to obtain odds ratios (OR).
Results: Significant changes in SCr across shift were observed overall (p < 0.01) and by age, sex, and workload (p < 0.01). Age and sex were significant predictors, with higher SCr among those in heavier workload categories. In the adjusted logistic regression, female workers had lower odds of AKI compared to males (OR = 0.22, p = 0.05), while age and workload were not significant predictors although sample size was small. Interaction terms between age and sex or workload were not significant. The models are being examined for an association between eCT and cross-shift SCr or AKI as well as interactions with workload and these results also will be presented.
Conclusion: Age, sex, and workload were associated with cross-shift changes in kidney function among sugarcane workers, with female workers showing lower odds of AKI, highlighting the need for targeted protective measures—especially for older individuals and those performing high-intensity labor in hot environments.