The Issue Of Drug Testing In Safety-Sensitive Positions
Every individual has the right to a safe workplace. Safety can be ensured when an individual is healthy and free from stress, exhaustion and hazards in the workplace. Drug and alcohol testing is one method employers sometimes use to ensure the safety of employees in “safety-sensitive positions”. The Canadian Human Rights Commission’s Policy on Alcohol and Drug Testing states that, a safety-sensitive position is one in which incapacity due to drug or alcohol consumption could result in significant risk of injury to the employee, others or the environment. Safety-sensitive positions are included in transportation, aviation, defense, mining, forestry and transit sectors. Employment in these industries sometimes involve pre-employment and random testing of applicants and employees for drug and alcohol use.
But the issues surrounding the use of alcohol and drugs are complex. Ontario's Human Rights Code enacted in 1962, sets out the right of individuals in Ontario to be free from discrimination in the social areas of employment on the grounds of disability. The Canadian Human Rights Act defines dependence on drugs or alcohol (substance dependence) as a disability. This means that when an employee is diagnosed with substance dependence, the employer has to accommodate them in the workplace and provide them with individualized assessment and support like in case of any other disability. Drug and alcohol testing is undoubtedly very crucial in ensuring the safety of employees and others in the workplace. The tests mandated include testing for the concentration of alcohol, metabolites of marijuana and cocaine, opioids and prescription drugs like amphetamines in urine or oral fluid samples.
According to the World Drug Report 2019 published by the United Nations, most widely abused drug worldwide is Cannabis, with an estimated 188 million people having used the drug in 2017. Cannabis is a natural product of the plant Cannabis sativa, the main psychoactive constituent of which is delta9-tetrahydrocannabinol (THC). Cannabis plant is used for smoking consumption through various preparations like “Marijuana' which is the dried leaves and flowering tops of the plant and “hashish” which is dried resin of the plant.
The pharmacokinetics of cannabis differs with its route of administration. Upon smoking cannabis, THC reaches a maximum plasma concentration within minutes, exerts its psychotropic effects within seconds, reach a maximum after 15 to 30 minutes, and taper off within 2 to 3 hours. Following oral ingestion, psychotropic effects set in after 30 to 90 minutes, reach their maximum after 2 to 3 hours and last for about 4 to 12 hours, depending on dose and specific effect.
Cannabis is highly lipophilic and thus it is rapidly distributed in tissues such as heart, lung, brain, muscle and liver as well as adipose tissues. Prolonged exposure of cannabis leads to the formation of fatty acid conjugates of THC that get stored in tissues for extended periods. The half-life of infrequent users is 1. 3 days and for frequent user it is 5 to 13 days. This leads the toxic effects to persist in the body and become unpredictable.
Cannabis is primarily used for recreational purposes as the psychoactive effects on brain include feeling high or euphoric, a sense of well-being, relaxation and heightened sensory experiences for sight, taste, smell and sound. Cannabis affects the reward systems in the brain to exert these effects by inducing release of endorphins from the nucleus accumbens and the orbito-frontal cortex, and also by acting as a dopamine agonist in the brain, stimulating reinforcement regions in the meso-telencephalic dopamine (DA) system. Short term health effects of Cannabis also include slowed reaction time, problems with balance and coordination, increased heart rate and appetite, problems with learning and memory, anxiety and mental health problems.
These health effects of Cannabis on cognition and balance and coordination mandate the drug testing procedures to be in place for employment in safety sensitive professions. Cannabis can be detected in saliva, blood, urine, hair and nails. The preferred screening test is Immunoassay using urine dip tests. Screening tests are for instant detection and not very costly. One of the issues that exist with these screening tests is the false positive results that can occur through structurally related drugs like Ibuprofen, Naproxen, Ketoprofen, Promethazine, Pantoprazole, Riboflavin. Other substances that can create false positive results are Baby Soaps and Shampoos. Oral fluid testing is the best test for workplace testing. The oral mucosa is exposed to high concentrations of THC during smoking. Several hours after exposure, the oral mucosa serves as a depot for release of THC into the oral fluid (saliva). Compared to urine, the detection time in oral fluids is shorter which makes it more indicative of recent marijuana use.
But the screening for Cannabis does not work in the same way as the breathalyzer works for alcohol. The pharmacology of Cannabis is complex and it can stay in our bodies for prolonged periods of time after use. Thus, a positive test of THC would not imply impairment of an employee when reporting at work. Moreover, Cannabis preparations are also prescribed medically for management of severe and chronic conditions. Sativex is approved in Canada for symptomatic relief of spasticity in multiple sclerosis, neuropathic pain and severe pain in advanced cancer and Epidiolex is approved in U. S. for the treatment of seizures associated with two rare and severe forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome. These issues put at risk those employees who are randomly tested for drugs in safety sensitive positions.
Thus, we can conclude that due to the complex pharmacology of the cannabis, the drug testing at workplaces cannot pinpoint on impairment at the time of test but these tests when in place can safeguard the interests of the employees and others around them. The employers though should be willing to accommodate the employees who are identified as substance dependents and provide them with individualized assessment, counselling and support.
