Heat-related illness in agricultural workers

Abstract

Introduction: With rising global temperatures, agricultural workers are vulnerable to health problems associated with heat exposure. Studies document farmworkers’ reported symptoms following strenuous activities in hot environments, but physiological signs of heat related illness (HRI) have not been reported in this population. Methods: University researchers partnered with a farmworker advocacy organization to recruit 88 Hispanic nursery and fernery workers from central Florida. Subjects were monitored over a 3-day work period during hot summer months and asked to recall symptoms of HRI (excessive sweating, headaches, dizziness, muscle cramps, nausea/vomiting, confusion and fainting). Serum osmolality and urine specific gravity were indicators of dehydration. An ingested sensor recorded core body temperatures (Tc) every 30 seconds during the workday. Results: Most workers were female (64%), had a mean age of 37.9 years (SD 7.4) and worked an average of 7 hours per day. The mean BMI was 29.3 (SD 4.3). Workers reported an average of 2.4 HRI symptoms during the previous 7 days [women 2.9 (SD 1.6); men 1.7 (SD 1.4)]. Dehydration (urine specific gravity ≥1.02) was observed among half of workers before work; after work, three-quarters of workers were dehydrated. 82% of workers experienced at least one day with Tc exceeding 38°C, the threshold limit value set by the American Congress of Governmental and Industrial Hygienists. However, workers who began their work shifts in a dehydrated status were not more likely to report heat-related symptoms nor to experience at least one Tc reading above 38°C. Conclusions: HRI symptoms are frequent among agricultural workers. High rates of dehydration and Tc exceeding recommended levels were commonly observed. These findings substantiate the need for educational programs and strengthened policies to inform and protect workers on ways to prevent HRI.