Demographic composition, heat and physical effort exposure, intervention, and sampling strategy of studied job categories of fieldworkers
| Burned cane cutters | Seed cutters | Drip irrigation repair workers | Field support | |
| n* | 158 | 190 | 128 | 54 |
| Demographics | ||||
| % men | 100 | 72 | 53 | 65 |
| Age, median (IQR) | 30 (25–37) | 26 (23–33) | 29 (23–34) | 31 (25–35) |
| Work characteristics | ||||
| Previous harvests, median (IQR) | 7 (4–13) | 4 (2–6) | 4 (2–6) | 5 (1–8) |
| First ever harvest, n (%) | 0 | 14 (7) | 10 (8) | 6 (11) |
| Work setting | Cane fields burned 12 hours earlier | Green cane | Open fields | Open fields |
| Work task | Cut burned cane, top foliage and leave in rows on ground. | Cut cane at stem, then into 3–4 pieces. Later, pieces are bundled into packages of 10–11.5 kg. | Repair underground drip irrigation tubes requiring digging, bending, prolonged squatting. | Supervisors, work organisers, health promoters, hydration operators. Some occasionally walk long distances. |
| Physical demands† | Very high | High | Moderate | Light |
| Work schedule | 06:00–noon | 06:00–14:00, cutting ends at noon | 06:00–14:00 | 06:00–noon–14:00 |
| Mobile clinic | Daily | Daily or every other day | None | Many are implementers of the intervention with access to water and shade, but no clear rest recommendations. |
| Health promoter | Yes | Yes | Every other day | |
| Water distribution | Yes | Yes | Yes | |
| Lunch provided | Yes, end of work | Yes, during noon rest | No | |
| Tent | Yes | Yes | Yes | |
| Stool provided | Yes | Yes | No | |
| Population sampling | ||||
| Sampling strategy | All | All | Two of four work groups (one female, one male) | All present in fields with job groups studied |
| Mid-harvest testing, n (%) | 137 (87) | 151 (79) | 96 (75) | 19 (35) |
| Dropout, n‡ (%) | 33 (21‡) | 46 (23‡) | 23 (17‡) | 12 (21‡) |
| Baseline eGFR, median (IQR) (mL/min/1.73 m2) | 97 (80–114) | 110 (87–122) | 109 (93–123) | 112 (96–121) |
| Questionnaire | ||||
| Pesticide use during harvest§, n (%) | 6 (5) | 3 (2) | 3 (3) | 2 (5) |
| Incident fever§, n (%) | 12 (9) | 16 (11) | 12 (11) | 4 (10) |
| Chikungunya during harvest, n (%) | 5 (3) | 3 (2) | 0 | 1 (2) |
| NSAID use, n (%) | 40 (25) | 39 (21) | 29 (23) | 8 (15) |
| Current smoking, n (%) | 55 (35) | 55 (29) | 23 (30) | 10 (19) |
| Daily liquid intake end-harvest vs baseline change§ (L), median (IQR) | 4.9 (2.1–8.3) | 2.8 (0.1–5.9) | 4.4 (1.8–5.8) | 2.6 (1.0–4.4) |
| End-harvest electrolyte solution (boli) intake§ (L), median (IQR) | 0.75 (0–1.05) | 0.6 (0–0.9) | 0.9 (0–1.2) | 0.9 (0.6–2) |
| End-harvest daily sugary beverage intake§ (L), median (IQR) | 0.5 (0.2–1) | 0.5 (0.2–0.9) | 0.5 (0.2–0.9) | 0.5 (0.4–0.8) |
| Diabetes, n (%) | 0 | 1 (1) | 1 (1) | 1 (2) |
| Hypertension (self-reported and/or measured (>140/90 mm Hg)), n (%) | 5 (3) | 6 (3) | 2 (2) | 1 (2) |
*Number of workers including those followed up at the end of harvest and dropouts contacted after harvest.
†Physical demands order based on observation.
‡Denominator includes all recruited and also those who had no follow-up at all.
§Only includes those finishing the harvest.
eGFR, estimated glomerular filtration rate; NSAID, non-steroidal anti-inflammatory drug.