Waterandelectrolyte balance in workersexposed to ahot environmentduringtheirwork shift

We have investigated water and electrolyte balance in naturally heat-acclimatized workershaving free access to water and performing light to moderatework in a warm environment during their regular 8 hour work shift. The study was conducted at the metal workshops of two plants located in the south of Israel in midsummer. Thirty-twoworkers were studied in Sdom, an extreme desert, and 13 in Beer Sheva, a semi-arid zone. The average WBGT at the work area ranged from 26°eat the beginningof theworkshift to29°eattheendinSdom, and24°eto25°e, respectively, in Beer Sheva. Venous blood samples and body weights were taken before and after the work shifts. Three times during the work shifts, oral and skin temperatureswere measured.Themeanweightedskintemperaturesincreased 3-8°e in Sdom and 1Aoe in Beer Sheva during the work shifts, with a slight increase in oral temperatures.No weight loss was detected at the end of the work shifts. Haematocritvalues decreased at the end of the work shifts while the other variables measuredin the bloodand serum were unchanged.Blood and plasmavolumes increasedduringtheworkshifts. Thedataindicatethatwaterand electrolyte balancewas maintained.We concludethatwhen a naturallyheat-acclimatized individualperformslight tomoderatework(choosing his ownworkregimen) during his work shift in a warm environment, while having free access to drinking water and electrolytes, he maintainswater and electrolyte balance.