Alcohol and Cannabis use among SA miners

Alcohol misuse is a major public health concern in South Africa today. Cannabis (popularly known as dagga locally) constitutes the main drug of 
abuse in Africa (2) and early reports of its use on this continent date back to the 11th century in Egypt (ref 7). In South Africa, the prevalence of alcohol 
dependence among adults is estimated as 10% (ref 10), while that of risky drinking among workforces such as the mining industry has been estimated at 25% or more (7).   
In the workplace, substance abuse is associated with employee illness, occupational accidents, increased health services utilisation, and decreased productivity (3,4). Despite the fact that South Africa is one of the major mining countries in the world, there is paucity of data locally on alcohol and cannabis use among mineworkers.  
1.1 Prevalence of substance use   
In a South African gold mine, the prevalence of risky drinking among workers, the majority of which were in unskilled or semiskilled occupations, was found to be 32% (8). In other studies in South Africa, the highest rates of alcohol abuse as a household problem (32%) were reported among unskilled manual workers, while the lowest rates (9.1%) occurred among professionals (9).  Among miners in Argentina, 34% were found to be weekly alcohol drinkers, while 65% chewed coca leaves daily (10). In 1984, the Addiction Research Foundation in Canada reported that 11% of adults in Ontario above 18 years old used cannabis (11).    
1.2 Prevalence of accidents in which tests for substance  use were positive
In a review of trauma patients in a large mine hospital in South Africa, blood alcohol concentration (BAC) was over 0.08g/100ml in 5% of cases of occupational injuries (ref 13). In a South African pulp mill, blood alcohol was found to be positive in 18% of cases of injury.  In studies carried out in a Zambian Copper mine, alcohol tests were positive in 30% of accident cases; among a different group of mineworkers at this mine, one third of those subjected to a pre-shift random breathalyser testing, tested positive for alcohol with a reading of over 17.6mmol/l in 9% of cases; and two-thirds of another group of employees who had been suspected to be under the influence of alcohol and referred for alcohol testing, had alcohol levels exceeding 35.2mmol/l (ref 3, old 17 and 18). In a study among fatalities in the workplace including the mining industry over an eight-year period in 
Alberta, Canada, 4.3% had alcohol levels greater than 0.08g/100ml, the legal limit for driving a car in Alberta (Alleyne BC used before i.e. now ref 11). In the same study over a four-year period, urine was positive for cannabinoids in 8.5% of cases.   
1.3 Factors associated with substance use  
Historically, practices in the Mining and Agriculture industries such as the “dop” system, migrant labour system, availability of cheap or free alcohol, and availability of alcohol on credit, may have contributed towards increased alcohol use in the South African workforce. The “dop” system, officially prohibited in 1961, entails payment of workers with alcohol in lieu of wages (12,13).   Factors such as being inexpensive and easy to procure, infrequent enforcement of criminal prosecution for cannabis-related offences, a perception that its use is not problematic, may contribute towards cannabis use (1). Poverty, boredom, and inadequate health education, have also been associated with substance use (14). In a South African gold mine the lifestyle of miners such as living apart from families for prolonged periods was found to encourage unhealthy alcohol consumption (14).   Higher rates of alcohol use have been found among miners who have only ever worked underground compared to those who work aboveground, and among miners with a heavy workload (10). Daily use of coca was also found to be significantly higher among miners with a heavy workload (10). Stressful working conditions as are found underground, and heavy workloads may encourage alcohol and drug use, which may serve as a coping mechanism (15,16). Stress, loneliness, and boredom have also been cited as reasons for alcohol use among South African mine workers (8). In other studies in South Africa, alcohol was reported to be a problem in 32% of households of which the head was an unskilled manual worker compared to 9.1% of households of which the head was a professional or a white-collar worker (ref  12).    
1.4 Effects of substance use 
1.4.1 Effects of alcohol use  
Alcohol has a depressant effect on the central nervous system (CNS) (ref 6). Delayed effects of acute alcohol intoxication include interference with hand/eye coordination, precision in manipulation, and object-positioning tasks (ref 4). Other effects of alcohol include decrease in concentration, reaction time, and decision-making ability decrease in concentration, reaction time, and decision-making ability, increased risk of human error, and accidents (ref 6). Absenteeism, sick leave, and accidents have been found to be higher among workers who use excessive alcohol (3,17). Excessive alcohol use is also associated with social problems like violence, and can predispose to illnesses such as hypertension, gastritis, liver cirrhosis, gout, tuberculosis, and physical dependence with withdrawal symptoms, and depression (19). It can also lead to an increase in labour relations problems due to arguments, increased stress and workload on co-workers, and increased cost due to factors such as sickness and absence, re-training and loss of expertise (ref 6). 


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