Evaluation of heat stress in migrant farmworkers

BACKGROUND. The rate of heat-related fatalities in crop production workers is almost 20 times that of other industries. University researchers, in partnership with clinicians and outreach workers at a migrant health center, sought a better understanding of the risks to migrant and seasonal tomato workers during the summer months.

METHODS. Heat stress was investigated in tomato workers in July 2012 using measurements of body temperature, heart rates, body weight loss, evaluation of the thermal environment, and survey data.

RESULTS. Using occupational safety criteria, these workers were found to work under conditions that should require protective measures to prevent heat strain. Increases in body temperature, heart rate, and physiological strain correlated with heat exposure. One-third of workers had percent losses in body weight that indicated dehydration. However, working under hot conditions appeared to elicit a low magnitude of heat strain in well-acclimated workers who self-pace. Survey data showed that less than 30% have had any heat-related safety training.

DISCUSSION. Findings of this study, one of the first with physiological measurements of U.S. crop workers, indicate the need for worker and employer safety training regarding acclimation, hydration and self-pacing.