Heat stress and workload associated with sugarcane cutting - an excessively strenuous occupation!
Extreme Physiology & Medicine volume 4, Article number: A23 (2015)
Chronic kidney disease not associated with traditional risk factors (sometimes called Mesoamerican nephropathy) is prevalent in male agricultural labourers, particularly sugarcane cutters, in Central America and Mexico regions . Strenuous work in a hot environment with dehydration is believed to be a key causal factor . The aim of this study was to assess the level of heat stress and workload in sugarcane cutters.
45 sugarcane cutters (34(12) y; range 18 - 57 y) from El Salvador were studied during the 2015 harvest (Feb-April). Heart rate (HR, Polar) was recorded in 10-11 workers per day, during 7 workdays. Weather data was collected using two weather stations (Weatherhawk, QuesTemp °34). Outdoor Wet Bulb Globe Temperatures (WBGT) was calculated (WBGT (outdoor) = 0.7WB + 0.2G + 0.1DB) via the QuesTemp °34. HR data were expressed a percentage of maximal HR (%HRmax). A regression equation was used to predict HRmax (208 - 0.7 × age) .
Sugarcane cutters worked on average for 7:30 hours (range 3:20 - 9:36 hours). In the field, WBGT reached 32.1°C (95% confidence interval [CI]: 33.0°C to 31.1°C), with 79 % (95% CI: 87 to 71%) of the day spent working at a WBGT above 26°C (threshold limit for continuous harvesting at 100 % ). Heart rates averaged 54 %HRmax (95% CI: 57 to 52 %HRmax) across all workdays. Workers spent 4:44 hours (95% CI: 5:19 to 4:09 hours) working at ≥50%HRmax and 2:48 hours (95% CI: 3:21 to 2:15 hours) working <50%HRmax.
Sugarcane cutting is repetitive high-intensity work carried out in high heat stress conditions. Workers spent over half the workday (including rest breaks) working at and above 50% of their HRmax. This HR intensity is similar to that exhibited in the first 12 hours of adventure racing (64%HRmax ) and higher than that maintained by soldiers during multi-day operations (30 - 40% of aerobic power ).
The cardiac strain of sugarcane cutting is similar to that associated with very prolonged, competitive exercise and higher than that typically associated with self-paced hard work. Yet, sugarcane cutters maintain this work intensity daily throughout the harvest (~6 months).
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Lucas, R.A., Bodin, T., García-Trabanino, R. et al. Heat stress and workload associated with sugarcane cutting - an excessively strenuous occupation!. Extrem Physiol Med 4 (Suppl 1), A23 (2015). https://doi.org/10.1186/2046-7648-4-S1-A23