Dating back to prehistoric times, it is known that individuals consumed drugs to lessen physical pain or change their state of perception. More so, drug usage was limited for matured people or very specific circumstances. Recently, drug use and abuse is a very pertinent social and public health problem that calls for communal concern. This is because of the extensive utilization of drugs in many sectors of the population. More problematic is the usage of drugs by the immature of society and the gravity on the individual and community. Effects of the phenomenon on the three levels in the current concept of health- physical, psychological and social.There are many definitions of drug abuse or substance abuse related to taking a psychoactive drug or performance-enhancing drug for a non-medical effect (Rehm, Taylor and Room, 2006 and NACADAA, 2009). Basically, Head, Stansfeld and Siegrist (2004) state that, it refers to the overindulgence in and dependence of a drug or other chemical leading to effects that are detrimental to the individual’s physical and mental health, or the welfare of others. Numerous studies: (Frone, 2006, Moore et al., 2009 and Ndetei et al., 2004) have established that some of the most commonly abused drugs include alcohol, amphetamines, barbiturates, benzodiazepines, and opiates (codeine, hydrocodone, cigarettes, heroin, morphine etc. Usage of these drugs may lead to possible physical, social, and psychological harm, both strongly depending on local jurisdiction (Mosby’s Medical, Nursing and Allied Health Dictionary, 2002). More so, Pham-Kanter (2001) says that even though legal substances such as alcohol and nicotine unquestionably can be and are abused, talking about drug abuse, sets in our thinking two kinds of situations: use of illegal substances such as marijuana, cocaine, heroin and misuse of legal drugs such as, alcohol, cigarettes, prescription drugs or fumes from household products. (WHO, 2004) puts forth that, even a small amount of an illegal or improperly consumed substance can change the proper functioning of the brain, and the user behaves out of the normal due to the drug, its use constitutes abuse. More risky, the short-range outcomes of the drug whether they include euphoria, extra energy, sensory enhancement, or heightened performance – tend to become so appealing that the drug takes over the user’s life, disrupting his or her relationships, work, and peace of mind (Shauri and Omondi, 2004).Drug abuse may lead to addiction or dependence (Frone, 2003) and Substance Abuse and Mental Health Services Administration (SAMHSA), 2007) and Moore et al., 2009). Medically, physiologic dependence entails the development of tolerance leading to withdrawal symptoms. Several researches (French et al., 2001, Mohr, Charles and Truxillo, 2005 and WHO, 2004) have endeavoured to differentiate both abuse and dependence from addiction. On one hand they say that addiction involves a urge to continue using the substance despite the negative consequences, and may or may not involve chemical dependency. However they point out that dependence almost always implies abuse, but abuse can occur without dependence, particularly when an individual is a beginner. Dependence involves physiological processes whereas substance abuse reflects a complex interaction between the individual, the abused substance and society (Mosby’s Medical, Nursing and Allied Health Dictionary, 2002).Drugs exist in different types and forms. Some of these substances are natural in origin like tobacco or cannabis, marijuana while others are a product of chemical processes gotten from natural products like alcoholic beverages, which are obtained from the fermentation or distillation of grain or fruit juice. There is also the production of artificial drugs as is the case with psychiatric use for synthetic drugs. There are several criteria in classifying drugs. On the foundation in conformity with laws, drugs are classified as legal which include; alcohol, tobacco, , etc. and illegal, comprising of, etc. In addition, there is also the distinction of between soft and hard drugs although presently the difference is negligible owing to the fact that it can lead to mistaken interpretation that soft drugs are not quite harmful to health. There are many types of drugs, some include; Alcohol, Tobacco, marijuana, coffee, hypnotics, sedatives, inhalants opiates, cannabis, cocaine, synthetic drugs, hallucinogens etc. Recently, the new drug usage is tramadol. For this study, the concepts of alcohol, tobacco and marijuana will be elaborated.The Concept of AlcoholAlcohol abuse is a pattern of drinking that the result is harmful to one’s health, interpersonal relationships, or ability to work. That is, the constant use of alcoholic beverages with disregard to its attached harmful effects. It is also termed as alcoholism. Alcoholics can be regarded as either being anti-social alcoholics or anxiety-ridden alcoholics. As for the latter, they can stay for a long period of time without drinking but typically cannot control themselves when they start drinking. The adolescent generation of the United Kingdom’s were ranked as the heaviest drinkers according to an international survey. As said by the American Medical Association (2009), alcohol abuse is a disease that supports classification of both physical and mental aspects. It is held that the Social environment which includes anxiety, age, family, sex and mental health determine the risk level for the condition. Alcoholism produces alters in the structure of the brain and chemistry. These changes keep alcoholic individual going making it difficult for the person to change his/her habit and also result to alcohol withdrawal effects once the person stops. The alcoholics may not be able to identify this habit. According to (Gelder, Mayou and Geddes, 2005) ease in accessing alcohol is one of the major contributing factors among people engaged in its abuse. According to the National Council on Alcohol and Drug dependence, alcoholism is a chronic disease influenced and enhanced by aspects that are genetic, psychological or environmental. Lack of control, over usage of alcohol, constant use of alcohol while ignoring its effects and bent thought patterns characterize this disease. A majority of the world’s population indulge in risky behaviours that could materialise to alcoholism. The genetics of alcoholismScientifically, there is rising amount of proof that links genetics to alcoholism. Possibilities have been investigated through studies on familial transmissions of the phenomenon and that environmental factors do not solely affect alcoholism. Behavioural patterns that impacts families with a habit of alcohol abuse form the basis for the research. Nevertheless, more studies on the relationship between genetics and alcoholism are still ongoing (National Institute on Alcohol abuse and Alcoholism, 2009). A research involving two pairs of twins raised by separate parents with different alcoholic adoptive patterns showed that proneness to alcoholism was generally higher among the pair of twins with a biological father who was alcoholic as compared to the twins born of a father who was non-alcoholic. Alcoholism was also revealed to likely occur among identical (i.e. monozygotic) twins who have the same genetic components, in comparison to fraternal (i.e. dizygotic) twins who share their genes up to only 50% (Agrawal & Lynskey, 2008). Also, family studies which investigates the members of a family (both alcoholic and non-alcoholic members)for the presence of the disease have also provided convincing evidence that the risk for alcohol dependence is determined partly by genetic influences ( Gelernter & Kranzler,2009).The Concept of TobaccoCigarette smoking, as it exists in the world today, is a most remarkable phenomenon. It is a habit of the most widespread proportions, and a product of the twentieth century. Nowadays, the consequences of cigarette smoking is felt in almost every area — in politics, economics, psychiatry, psychology, sociology, anthropology, pharmacology and pathology (NIDA, 1977).It is an agricultural crop, grown in warm climates most commonly used to make cigarettes. The psychoactive component is nicotine which is nervous system stimulant that causes complex biochemical and neurotransmitter disorders. It elevates heart rates and blood pressure, constricts blood vessels, irritates lung problems and reduces your ability to taste and smell (PAMF, 2015).Tobacco can be smoked like manufactured cigarettes which is the most product being used and some are non-smoked (i.e administered via smokeless products) like snuff which is sniffed. The former is highest being use probably due to the ease of accessibility and its lower cost of getting as compared to the smokeless which is scarce and expensive. Also manufacture cigarettes, its importation and distribution is not banned in countries even with its effects on the individual. Whereas, smokeless tobacco is a banned in most countries may be due to its adverse consequences on health. Tobacco affects both the user and non users (second-hand smokers) found around him/her at the moment of consumption. It is worth nothing that second hand smokers are affected more than the users. It is believed that tobacco is consumed in order to regulate mood or to increase pleasure. Also it acts as source of relief stressful moments and in periods of high emotions. The consumption of tobacco has an effect employees performance viewed in terms of behavioural-mood changing, exposure of risk to non users, pollution of the environment, accidents and consequently a drop in productivity which is a burden and increase in the cost of the employers. This is affirmed by (Michael T Halpern, Richard Shikiar, Anne M Rentz, Zeba M Khan, 2017) who showed that, the costs associated to smoking are principally important to employers. Outside of increased medical care costs attributable to tobacco intake,, employers incur extra indirect costs for smoking employees. Hence, the prohibition of tobacco consumption in the workplace. Also, tobacco consumption is very common among manual workers as compared to other professional occupations. This is in line with the study conducted by GK Medhi, NC Hazarika and J Mahanta, (2002-2003).in which the results obtained revealed that the consumption of alcohol and tobacco by workers in the tea industry was higher than those of other occupational groups. This may be due to the fact the difference in educational background. That is, the level of education is higher among the less educated and vice versa.As shown by the findings of the study carried out by GK Medhi, NC Hazarika and J Mahanta, (2002-2003), those without a formal education revealed a 35.3%, alcohol usage and 58.2% tobacco usage. Similarly, in school dropouts the results were 30.8%, and 47.6% in alcohol and tobacco consumption respectively. This may be liable to the fact that, the less educated may be less aware of the dangers of tobacco and alcohol and more likely to be exposed to risk taking behaviors, predisposing them to serious diseases (Rani et al, 2003; Seth et al, 2004). This will lead to increase in morbidity and motality.The Concept of Marijuana Just like tobacco, marijuana dates far back into history. Marijuana is a common drug abused in many countries. It refers to the leaves and flowering tops of the cannabis plant. That is a tobacco-like substance that is produced by drying the leaves and flowering tops. THC delta-9-tetrahydrocannabinol) is believed to be the chemical liable for most of the mind altering consequence resulting from the consumption of marijuana (PAMF, 2015). Even though there are more than 60 cannabinoid chemicals present in cannabis products, the major psychoactive agent is ?-9- tetrahydrocannabinol (THC). This is metabolized in the body to 11 hydroxy-tetrahydrocannabinol (11-OH-THC), which is also psychoactive. 11-OH-THC is further oxidized to ll-nor-?-9-carboxytetrahydrocannabinol (COOH-THC), which is not psychoactive and is the main urinary metabolite. Blood THC levels fall rapidly to about 10 percent of peak concentration an hour after smoking. More so, COOH-THC can appear in urine for more than a few days after cannabis has been smoked. In order to determine if cannabis has recently been used, a certain degree of THC will probably be found in the blood. (Michael N. Bates and Tony A. Blakely, 1999). The effect of THC and its impact on the brain has been studied by scientists. Furthermore, it was realised that, when someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to organs throughout the body, including the brain. Also. in the brain, THC connects to specific sites called cannabinoid receptors on nerve cells and thereby influences the activity of those cells. Some brain areas have many cannabinoid receptors; others have few or none. Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement.,( NIDA 2002)The consumption of marijuana or cannabis can lead to more devastating effects on the consumer especially on employees, in terms of change of behaviour, health, etc. That is the consumption of marijuana leads to change in the mood, which may impair decision making of the worker, their relationship with other workers and or clients, lack of concentration which may lead to increase probability of accidents and many others. Some of the health problems include; daily cough and phlegm production, regular acute chest illnesses, high risk of lung infections, and a greater propensity toward obstructed airways. This is very common to the effects of tobacco but very disastrous as opposed to tobacco. These will lead to more sick leave days, lateness to work and in the long run death. All these have negative impacts on the level of productivity. For workers in the agricultural sector, the effect is disastrous because they need a lot of strength to carry out their activities. Recently, marijuana is used in hospitals and prescribed as a drug. This is known as medicinal marijuana, which refers to using the whole unprocessed marijuana plant or its basic extracts to treat symptoms of illness and other conditions. Marijuana is being prescribed as drugs in some parts of U.S.A. interestingly; there are two main cannabinoids from marijuana that attract medical interest. They are; THC and CBD. The former can increase appetite and reduce nausea, pain, inflammation and muscle control problems while the latter is cannabiniod that dose not make people “high”but decrease Pin, inflammation, control epileptic seizures and possibly treat mental illness AND addictions. Notwithstanding, many researchers are in the continual process to explore the possible uses of THC, CBD and other cannabinoid for medical treatment (NIDA, 2017).