CHAPTER 2: LITERATURE REVIEW
5.4 TYPE OF FLUID CONSUMED
Most of the forestry workers primarily drank the water supplied by the contractors, although some brought a limited variety of other fluids including amahewu, tea and cold drink. A limited variety of fluid promotes taste fatigue and a decreased fluid consumption. Water is not the optimal fluid as it does not contain the necessary CHO and electrolytes (sodium) required for prolonged physical activity. The consumption of
152 large amounts promotes the risk of dilutional hyponatremia (Sawka et al 2007, Maughan et al 2004, Clapp et al 2002).
Amahewu was an excellent choice of fluid as it is a culturally acceptable 7% flavoured CHO solution which contains 26 mg of sodium per 100 ml76 (Sawka et al 2007, Wildman
& Miller 2004 p248). In previous years, the Richmond contractor supplied locally made amahewu to the forestry workers (Kamhoot 2005). After a while the workers refused the drink as they claimed that the amahewu gave them diarrhoea because the contractor had poisoned it (Kamhoot 2005). The high incidence of diarrhoea (9% - 17%) in both areas was more likely to have been a consequence of HIV/AIDS and/or food poisoning.77
The cold drinks that the forestry workers brought to work tended to be 4 to 6% CHO solutions and, although sodium free, they were appropriate choices. Judging from the amounts that the forestry workers carried into the forest, neither the amahewu or cold drinks were consumed in sufficient quantities to supply adequate CHO.
Regardless of the cause, the diarrhoea further increased the risk of dehydration by increasing water loss from the body and by the workers’ reluctance to drink the fluid supplied by the contractors. The implication was that, although amahewu was a suitable solution for the workers, the forestry industry would need to implement an innovative method of providing the solution since this could not be supplied directly by the contractors due to the level of suspicion of the work force.
76Amahewu is a fermented mealie meal drink with CHO and sodium concentrations similar to that found in Energade and Powerade.
77 A small study done by the forestry industry in the Richmond area showed the incidence of HIV infection to be 4 out of 10 (Van Daele 2005). Food poisoning was a high risk as hot food was sealed in containers and then left to stand in the heat for the duration of the shift.
153 Tea sweetened with sugar was also a good CHO source, although the amount of CHO contained in the solution was difficult to determine as the workers were unclear as to how much sugar they had added. Although the literature previously discouraged the intake of tea and coffee because of the caffeine content and the potential diuretic effect (Parker et al 2001), the ACSM Position Paper (2007) stated that the ingestion of caffeine in amounts less than 180 mg/d would be unlikely to exacerbate dehydration (Sawka et al 2007). As the mean amount of caffeine (150 mg) contained in the volume of tea consumed by the workers in Nelspruit was less than this, the consumption of tea would have had no impact on hydration and may have increased their physical performance.
Even if water was the only fluid that the industry could supply, the temperature at which it was provided would either encourage or deter the intake, as fluid supplied at 15°C to 21°C is more likely to be consumed (Wildman & Miller 2004 p248). In Richmond no effort was made to place the water containers in the shade, therefore by midday the temperature of the water was unpalatable. In contrast, the Nelspruit contractor went to great lengths to supply as much frozen water as possible, even with very limited facilities.
This was greatly appreciated by the workers who came running to get the frozen water whenever they saw the truck approaching from a distance. This demonstrated clearly that even with similar restricted facilities, the attitude and effort on the part of the individual contractors could influence the fluid intake of the workers.
154 5.5 FLUID REQUIREMENTS
Fluid requirements could only be determined on a subsection of the male workers in this study. The mean fluid requirements per male worker were estimated at 439 ml per hour78 which extrapolated to 3.5 litres per 8 hour shift. These findings were similar to those of the only other study which investigated the fluid requirements of forestry workers (Paterson 1997). Based on average sweat rates, Paterson (1997) concluded that the NZ chainsaw operators required 500 ml of fluid per hour (4 litres per 8 hour shift). These amounts were lower than that of the ILO (5 litres per worker per day), the DME (1 to 1½ litres per hour) and the US military revised guidelines (710 to 946 ml per hour) (Montain et al 1999) but within the lower recommendations of the ACSM (400 to 800 ml per hour) (Sawka et al 2007). The implication was that the DME and the ILO recommendations for industry were unrealistic as were those of the US military with the possibility of promoting overhydration if followed locally.
This was the first study in SA to provide fluid guidelines suitable for local conditions in forestry. Being able to recommend a constructive guideline of 450 ml per male worker per hour, was a very important outcome of this study as contractors such as those in Nelspruit, had absolutely no perception of the amount needed or in fact how much they actually supplied. The one litre per worker per day supplied by the Richmond contractor was inadequate.
78 This was calculated by adding 412 ml per hour for those in Richmond who did not drink before the break and 465 ml per hour for those in Nelspruit who did not drink across the shift and then dividing this by 2 to get an average.
155 Although these guidelines were based only on the 8 male workers who did not eat or drink during the day, the size of other international studies investigating fluid requirements were comparable. Paterson (1997) arrived at a similar conclusion in his study based on 8 NZ male loggers. The widely applied revised US military guidelines were based on research conducted on 19 male soldiers. What does need to be taken into account, however, was the fact that these recommendations were based on data from male workers only – they may therefore be too high for female workers as females in general require less fluid and appear to be more susceptible to overhydration and dilutional hyponatremia (Twerenbold et al 2003). It should also be kept in mind that there is a wide individual variation in sweat rate, therefore, some workers may need to drink more and others less.