Dehydration from outdoor work and urinary stones in a tropical environment.

A questionnaire survey was carried out to determine the prevalence of urinary stone disease in 406 male workers in several occupations. There were 119 quarry drilling and crusher workers (outdoor, physically active), 77 quarry truck and loader drivers (outdoor, physically inactive), 92 postal deliverymen (outdoor, physically active), 75 postal clerks (indoor, physically inactive), and 43 hospital maintenance workers (indoor, physically active). The prevalence of urinary stone disease was five times higher in outdoor workers (5.2 per cent) compared to indoor workers (0.85 per cent, P less than 0.05). Contrary to expectation, no increased risk of urolithiasis was apparent in physically inactive workers. Chronic dehydration is likely to be the most important risk factor for the increased risk of urolithiasis in outdoor workers in the tropics, and should be easily prevented by increased water intake.