Prevalance of alcohol and substance use and relationship to safety

Alcohol misuse is one of the most significant public health concerns facing South Africa today. Globally, cannabis is the most widely used illicit drug, with an estimated 144 million people using it annually (1). It constitutes the main drug of abuse in Africa (2). Substance abuse is associated with employee illness, occupational accidents, increased health services utilisation, and decreased productivity (3,4). However, despite the fact that South Africa is one of the major mining countries in the world, local research on alcohol and cannabis use among mineworkers is limited.  
1.1 Prevalence of substance use    
It is estimated that 6% to 16% of the average workforce is likely to be alcohol dependent and that a further 20% is likely to experience drug related problems (5,6). In South Africa, the prevalence of alcohol dependence among adults is estimated as 10%, while that of risky drinking among workforces such as the mining industry has been estimated at 25% or more (7).    
In a South African gold mine, the prevalence of risky drinking among workers was found to be 32% and the majority of these employees were in unskilled or semiskilled occupations (8). In another study carried out 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 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, which may contribute to cannabis use, include the fact that it is inexpensive, easy to procure, prosecution is infrequently enforced, and is perceived by many not to be problematic (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 by South African mine workers (8). 
1.3 Effects of substance use  
1.3.1 Effects of alcohol use   
Absenteeism, sick leave, and accidents have been found to be higher among workers who use excessive alcohol (3,17). In a South African pulp mill, blood alcohol was found to be positive in 18% of cases of injury, while in a copper mine in Zambia, blood alcohol was positive in 30% of accident cases (17,18). 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).  
1.3.2 Effects of cannabis use  
Regular cannabis use has been associated with impaired social and occupational functioning (20). The primary psychoactive constituent is delta-9- tetrahydrocannabinoid (THC) (21). Cannabis use results in feelings of euphoria and relaxation, and acute effects include impairment of attention and short- term memory, and loss of coordination (22,23,24). Chronic effects include psychological dependence characterised by deterioration in psychosocial functioning; subtle cognitive deficits, particularly attention, learning, and executive functioning (organising and integrating of information); possible triggering of onset of schizophrenia; increased vulnerability to respiratory illnesses; impaired lung function; and precancerous changes in lung tissue (1,20).   
1.4 Screening tools for substance use
1.4.1 Screening tools for alcohol dependence  
The Diagnostic and Statistical Manual of the American Psychiatric Association, 4th edition (DSM-IV), defines alcohol abuse as a pattern of use which leads to clinically significant impairment or distress, as manifested by one (or more) of the following in a 12-month period (7):  

Recurrent alcohol use resulting in a failure to fulfil major role obligations at home, school, or work  ? Use of alcohol in situations in which it is physically hazardous (e.g. driving a car) ? Recurrent alcohol use leading to legal problems (e.g. drunken driving) ? Continued alcohol use despite persistent or recurrent social or interpersonal problems caused or exacerbated by alcohol. 

Screening tools for alcohol misuse include the CAGE, the AUDIT (Alcohol Use Disorder Identification Test), and the brief MAST (Michigan Alcohol Screening Test) questionnaires (25,26,27). They are specific and reliable, and help to screen individuals who require further assessment for alcohol dependence. The brief MAST is an abbreviated version of the original 25-item MAST published by Selzer in 1971, and like the AUDIT, it is also a 10-item questionnaire (7). The CAGE questionnaire was developed by Ewing and Rouse in 1970. Comprised of the following four questions, it is easier to administer (28):   

  • Have you ever felt you ought to Cut down on your drinking?    
  • Have people Annoyed you by criticising your drinking?
  • Have you ever felt bad or Guilty about your drinking?
  • Have you ever had a drink first thing in the morning to steady your nerves and get rid of a hangover? (Eye-opener) 
Two or three positive responses are highly suggestive of alcohol abuse and possible dependence, while four positive responses are virtually diagnostic.   
Laboratory tests or test combinations that can be used for screening alcohol abuse include mean cell volume (MCV), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), and uric acid (28).   
Breathalyser testing can be carried out to detect acute intoxication but cannot assess chronic misuse. On ingestion, alcohol is rapidly absorbed from the upper gastrointestinal tract. Peak concentrations of ethanol are attained approximately one hour after ingestion and factors influencing levels attained include the rate at which the drink was taken, whether it was consumed with food, rate of gastric emptying, and body habitus (28). Between 2% to 10% is eliminated in urine and breath (28).  
1.4.2 Screening tools for cannabis use    
Marijuana is usually smoked but may ingested, either incorporated into food, or as a liquid extract (tea). It is rapidly absorbed from the lungs into the blood with quick onset of effects. When ingested however, onset is slower but effects more prolonged. The natural metabolites of cannabis (cannabinoids) are found in blood, bile, faeces, and urine. It may be detected in the latter within hours of exposure (30). These metabolites being fat soluble, are stored in the body’s fatty tissues including the brain, for prolonged periods after use (30). It may be detected in urine months after last exposure, depending on the frequency and intensity of use (31).    
Qualitative screening for detecting cannabinoids in urine can be carried out using commercially available rapid tests and laboratory tests with varying levels of reported sensitivity and specificity. However, confirmatory laboratory tests, which also quantify the amount of cannabinoids in the urine, exist, of which the preferred method is the Gas Chromatography/Mass Spectrometry (GC/MS) method (31).      
1.5 Measures for control of substance use among mine workers   
The South African Mine Health and Safety Act of 1996 states that an employer must provide conditions for safe operation, and every employee must take reasonable care to protect their own health and safety, and that of other workers who may be affected by an act of omission on their part (32). It also states that no persons in a state of intoxication, or in a state likely to render him incapable of caring for himself or others in his charge, will not be allowed to enter a mine. This is also stipulated in Regulation 4.7.1 of the Minerals Act 50 of 1991 (33).    
However, there are no clear guidelines for implementation and the level of interpretation of this responsibility varies from mine to mine; from those in which there are no clear substance use guidelines, to those with draft policies, and to those with policies. Where policies exist, they describe the mine regulations in terms of substance use, under what circumstances testing will be carried out, how it will be carried out, and how results will be dealt with.   
In New South Wales most mines have an alcohol policy, which may include random testing, pre-shift self-breathalyser testing, and awareness programs (34). Buy-in of stakeholders is however of utmost importance in any control program.  
In 1995, the International Labour Organisation (ILO) adopted a code of practice on the management of alcohol and drug related issues in the workplace (35). This code emphasises a preventive approach and embraces the following principles:   
  • Joint assessment by employers, workers and their representatives of the effects of drug use on the workplace and their cooperation in developing a written policy for the workplace  
  • Consideration of alcohol and drug related problems as health problems, and a need to deal with them without discrimination, like any other problem in the workplace  
  • Recommendation that drug and alcohol policies should cover all aspects of prevention, reduction, and management of alcohol and drug related problems, and integration of relevant information, education and training programs where feasible, into broad-based human resources development, working conditions, or occupational safety and health programs.       
  • Establishment of ethical principles which are vital to concerted and effective action, such as confidentiality of personal information, and the authority of the employer to discipline workers for employment-related misconduct, even where it is associated with the use of alcohol and drugs.   
  • Consideration of fundamental legal, ethical, and moral issues involved in testing body fluids for alcohol and drugs and determination of when it is fair and appropriate to carry out such testing.    
  • The Occupational Alcohol Program (OAP) of the 1970s was one of the earliest attempts at addressing alcohol misuse in the workplace (36). This has been replaced in recent times by Employee Assistance Programs (EAPs) which are broader based and aim at addressing all personal problems that are affecting, or that have a potential to affect an employee (6,37).   
1.6 Motivation for this study 
Evaluating the prevalence, knowledge, and practice of alcohol and cannabis use among mine workers in South Africa in relation to health and safety, will help to find out more about substance use among this population and assist in development of recommendations to improve health and safety. This is of importance to the mining industry as this ultimately impacts on productivity and finances. The cost of alcohol and drug abuse to South Africa has been estimated at R 2 Billion per year (38, 39). This study aims to provide evidence on which health intervention strategies can be based.   
1.7 Study aim and objectives  
1.7.1 Overall Aim  
To determine the prevalence and factors which influence alcohol and cannabis use among mineworkers in South Africa.    
1.7.2 Specific objectives  
  • To determine the prevalence of alcohol and cannabis use.  
  • To determine the knowledge, attitudes, and practice regarding alcohol and substance  (cannabis) use amongst miners, and its relationship to health and safety.    
  • To determine factors which influence alcohol and cannabis use.        
  • To make the findings available to all stakeholders, so that appropriate recommendations can be implemented. 
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