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CDHO Advisory: Substance Use Disorder









Use of the dental hygiene interventions of scaling of teeth and root planing including curetting surrounding tissue, orthodontic and restorative practices, and other invasive interventions for persons1 with substance use disorder.


Cite as College of Dental Hygienists of Ontario, CDHO Advisory Substance Use Disorder, 2023-04-05


Scaling of teeth and root planing including curetting surrounding tissue, orthodontic and restorative practices, and other invasive interventions (“the Procedures”).



Substance use disorder


Addiction specific counselors
Advanced practice nurses
Dental assistants
Dental hygienists
Health professional students
Public health departments
Regulatory bodies


To guide dental hygienists at the point of care relative to the use of the Procedures for persons who have substance use disorder, chiefly as follows.

  1. Understanding the medical condition.
  2. Sourcing medications information.
  3. Taking the medical and medications history.
  4. Identifying and contacting the most appropriate healthcare provider(s) for medical advice.
  5. Understanding and taking appropriate precautions prior to and during the Procedures proposed.
  6. Deciding when and when not to proceed with the Procedures proposed.
  7. Dealing with adverse events arising during the Procedures.
  8. Record keeping.
  9. Advising the patient/client.


Child (2 to 12 years)
Adolescent (13 to 18 years)
Adult (19 to 44 years)
Middle Age (45 to 64 years)
Aged (65 to 79 years)
Aged, 80 and over
Parents, guardians, and family caregivers of children, young persons and adults with substance use disorder.


For persons who have substance use disorder: to maximize health benefits and minimize adverse effects by promoting the performance of the Procedures at the right time with the appropriate precautions, and by discouraging the performance of the Procedures at the wrong time or in the absence of appropriate precautions.



Terminology used in this Advisory and generally

Resources consulted 


Medical and scientific usages relating to substance use disorder (which includes drug and alcohol dependency)

  1. Addict, a person with the disease of addiction.
  2. Addiction, a chronic disease characterized by
    1. impaired control over one or both of
      1. use of one or more psychoactive substances
      2. behaviours
    2. manifestations variously in the realms of
      1. biology
      2. psychology
      3. sociology
      4. spirituality
    3. changes in mood
    4. relief from negative emotions
    5. provision of pleasure
    6. preoccupation with one or both of
      1. use of substance(s) 
      2. ritualistic behaviour(s)
    7. continued use of substance(s) despite adverse consequences 
      1. of a physical, psychological, or social nature
      2. arising from engagement in ritualistic or other behaviour(s) 
    8. a clinical course that may variously be
      1. progressive
      2. relapsing
      3. fatal.
  3. Agonist, a substance, such as methadone, that produces effects that are similar to but less harmful than those of a psychoactive substance to which treatment is directed.
  4. Alcohol problems, manifested by 
    1. empty bottles or cans in the garbage
    2. irritability, depression or confusion
    3. losing touch with friends or family
    4. loss of co-ordination, falls
    5. making excuses or making up stories to obscure the truth about drinking habits
    6. memory lapses following drinking
    7. neglect of personal care, including
      1. not bathing
      2. not eating adequately or at all (CDHO Advisory)
      3. not taking care of health problems
    8. sleeping problems 
    9. slurring of speech.
  5. Antagonist, a substance that counteracts the effects of a psychoactive substance by inhibiting or reversing its effects.
  6. Concurrent disorder, similar in concept to comorbidity, a physical or psychiatric disorder that 
    1. interacts with substance dependence
    2. requires specific diagnosis and treatment to achieve stabilization and, where possible, recovery.
  7. Craving, a biological and psychological urge to return to addictive behaviour, characterized variously by
    1. strong desire
    2. preoccupation
    3. impulsivity.
  8. Dependency, which includes psychologic dependence (relating to the user’s belief that the drug is needed to maintain a state of well-being) and physiologic dependence (resulting from biologic alteration of the user’s brain from continual drug use, and leading to drug tolerance whereby increasingly large doses are required to produce the same effects obtained earlier with smaller doses).
  9. Dual diagnosis, concurrent or comorbid disorders, consisting of psychiatric illness and substance abuse, and involving two distinct primary illnesses each of which requires specific and concurrent treatment, for example
    1. the person begins use of mood-altering substances to cope with the psychiatric illness; while the substances may have provided temporary relief they did not address the psychiatric illness
    2. the self-medication may lead to addiction, not likely to be cured by treating the psychiatric illness; neither will treating the addiction cure the psychiatric illness.
  10. Intoxication, a physiological condition that follows the administration of psychoactive substances and results in disturbances in 
    1. perception
    2. cognition
    3. affect
    4. level of consciousness
    5. judgment
    6. behaviour
    7. other psychological and physiological functions and responses. 
  11. Maintenance therapy, treatment of substance dependence 
    1. with a prescription drug, such as 
      1. methadone for opioid dependence
      2. nicotine replacement therapy for tobacco
    2.  to prevent or minimize withdrawal effects
    3.  to reduce the harm associated with 
      1. a particular method of administration, such as sharing needles
      2. dangers to health
      3. social consequences.
  12. Substance-related disorder, comprising 
    1. substance abuse, a pattern involving
      1. abuse of illegal substances or the abusive use of legal substances such as alcohol
      2. use that leads variously to significant problems or distress including
        1. failure to attend work or school
        2. substance use in dangerous situations like driving a car
        3. substance-related legal problems
        4. substance use that interferes with 
          1. friendships
          2. family relationships
    2. substance dependence, involving
      1. continued use of drugs or alcohol, despite significant problems related to their use 
      2. signs such as 
        1. increased tolerance or need for increased amounts of substance to attain the desired effect
        2. withdrawal symptoms with decreased use
        3. unsuccessful efforts to decrease use
        4. increased time spent in activities to obtain substances
        5. withdrawal from social and recreational activities
        6. continued use of substance despite awareness of serious physical or psychological problems.
    3. chemical dependence, alternative term for the 
      1. compulsive use of drugs or alcohol
      2. inability to stop their use despite the serious problems.
    4. substance-induced disorders, including intoxication, withdrawal, and other substance/medication-induced mental disorders.
  13. Tolerance, one of the following 
    1. need for substantially increased amounts of the substance to achieve intoxication or the desired effect 
    2. substantially diminished effect with continued use of the same amount of the substance. 

Types of substances productive of abuse, dependency, or addiction

  1. Depressant, a psychoactive substance that suppresses, inhibits or decreases some function of the central nervous system.
  2. Hallucinogen, a psychoactive substance that 
    1. alters cognition, affect, and perception
    2. may resemble psychoses (CDHO Advisory) in its actions 
    3. do not necessarily produce the gross impairment of memory and mental orientation that is characteristic of the psychoses.
  3. Inhalant, a volatile substance, such as a solvent, that vaporizes at ambient temperatures and that is also a psychoactive substance.
  4. Psychoactive substance, a substance that affects cognition, affect or perception, involving
    1. recurrent substance use in situations in which it is physically hazardous
    2. recurrent substance use resulting in failure in fulfilling major role obligations at work, school, or home
    3. recurrent substance-related legal problems.
  5. Sedative, reduces activity in certain parts of the brain and produces a calming effect.
  6. Stimulant, a category of psychoactive substance that activates, enhances or increases activity in the nervous system, and acts like adrenaline, one of the body’s natural stimulants. 

Imprecise and everyday usages of terminology

  1. Alcohol, ethyl alcohol is a clear, colourless liquid; alcoholic beverages get their distinctive colours from their other ingredients and from the processes of fermentation.
  2. Alcoholic, an individual experiencing alcohol abuse/misuse3 or dependence.
  3. Alcoholism, alcohol abuse/misuse, or alcohol dependence.
  4. Chemically dependent, substance-related disorder.
  5. Drug addiction, substance-related disorder.
  6. Drug habit, substance-related disorder.
  7. Narcotic, opioid such as heroin, morphine and related drugs; the opposite of stimulant.

Drugs of dependency

  1. Prescription medications available for lawful use in particular circumstances
    1. prescribed
      1. Amphetamines are stimulants; other or related stimulants include 
        1. caffeine
        2. cocaine
        3. ecstasy
        4. ephedrine
        5. methamphetamine 
        6. Ritalin®. 
      2. Anabolic steroids 
        1. are synthetic steroids with the same chemical structure as the steroids found in testosterone,  the male sex hormone 
        2. appeal to athletes and bodybuilders because of their anabolic  and androgenic effects.
      3. Benzodiazepines, prescription sedatives used mainly to relieve anxiety and to help with sleep.
      4. Cannabis sativa, also known as the hemp plant, is the source of marijuana, hashish and hashish oil, which are psychoactive substances.
      5. Cocaine, a highly addictive stimulant that
        1. produces “highs” 
        2. is called Crack in the form that can be smoked.
      6. Codeine, an opioid, is used to
        1. relieve mild-to-moderate pain
        2. reduce coughing.
      7. Crystal Meth, one of the street names used for methamphetamine.
      8. Doda 
        1. is created by grinding dried poppy husks or poppy seeds containing opiates into a fine powder
        2. is usually ingested with hot water or tea, rather than injected
        3. creates dependency
        4. is used in some communities in Canada. 
      9. Ecstasy, has a chemical structure and effects similar to those of amphetamine and to mescaline.
      10. GHB, gamma-hydroxybutyrate, is 
        1. a depressant
        2. produced naturally in the human body in very small amounts 
        3. potentially dangerous when taken as a recreational drug, especially in combination with alcohol or other drugs.
      11. Heroin is 
        1. an opioid 
        2. a dangerous and illegal drug with a high addictive potential
        3. an effective analgesic.
      12. Ketamine is
        1. a hallucinogen
        2. a fast-acting anesthetic and analgesic used primarily in veterinary surgery
        3. occasionally used in human medicine.
      13. LSD, lysergic acid diethylamide, is a potent hallucinogen.
      14. Mescaline is
        1. a hallucinogen
        2. found in 
          1. peyote cactus
          2. designer drugs.
      15. Methadone is
        1. a synthetic opioid 
        2. used to treat dependence on other opioids. 
      16. Methamphetamine 
        1. is a stimulant similar in structure to amphetamine
        2. possesses a high potential for abuse
        3. is limited in its medical uses for which the doses prescribed are much lower than those typically abused.
      17. Morphine, an opioid
        1. relieves pain
        2. relieves fear and anxiety 
        3. impairs mental and physical performance
        4. produces euphoria
        5. rapidly results in tolerance.
      18. Opioids 
        1. are a family of drugs that have morphine-like effects, and include
          1. codeine
          2. heroin
          3. morphine
          4. oxycodone 
          5. fentanyl
          6. carfentanil
        2. are used to 
          1. relieve pain
          2. control coughs
          3. control diarrhea
          4. produce anaesthesia
        3. produce euphoria, making them prone to abuse.
      19. OxyContin®   
        1. is a time-released analgesic used for 24-hr pain relief
          contains oxycodone
        2. is an opioid also contained in 
          • Endocet®
          • Oxycocet®
          • Percocet®.
      20. Rohypnol®, a sedative, is the brand name of flunitrazepam, a benzodiazepine that, in Canada and the US, is illegal to possess, traffic, import or produce.
      21. Street methadone, methadone sold or given to someone for whom it was not prescribed.

Used for non-medicinal purposes or illegally

  • Amphetamines
  • Anabolic steroids
  • Cannabis
  • Cocaine
  • Doda
  • Crack
  • Crystal Meth
  • Ecstasy
  • GHB
  • Hallucinogens
  • Inhalants
  • LSD
  • Marijuana
  • Methamphetamine
  • Rohypnol
  • Street Methadone

Other substances

  1. In food and drink or consumer products, such as
  2. Manufactured, imported, grown and/or distributed illegally, or are unregulated, such as
    • Cannabis4
    • Crack
    • Crystal Meth
    • Ecstasy
    • GHB
    • Hallucinogens
    • Inhalants
    • LSD
    • Marijuana5
    • Methamphetamine
    • Rohypnol
    • Street Methadone

Other medical or scientific terminology

  1. Affect, the experience of emotion and feeling.
  2. Anabolic, muscle-building.
  3. Androgenic, masculinizing.
  4. Central nervous system, the part of the nervous system that comprises the brain and the spinal cord.
  5. Cognition, the process of thinking.
  6. Palliative care, services of care for persons towards the end of life with terminal illnesses such as cancer, when the focus of the care 
    1. is relieving symptoms
    2. attending to physical and spiritual needs.
  7. Perception, the process of gaining awareness or understanding of sensory information.
  8. Supportive care, services of care to help persons meet the physical, emotional and spiritual challenges arising from the condition or its treatment.

Overview of  substance use disorder

Resources consulted

  1. Addiction 
    1. Is defined as a primary, chronic disease.
    2. Is characterized by impaired control over the use of a psychoactive substance and/or behaviour. 
    3. Exhibits biological, psychological, sociological and spiritual manifestations, such as
      1. change in mood
      2. relief from negative emotions
      3. provision of pleasure
      4. preoccupation with use of substance(s) or ritualistic behaviour(s)
      5. continued use of the substance(s) and/or engagement in behaviour(s) despite adverse physical, psychological and/or social consequences.
    4. Is associated in pregnancy (CDHO Advisory) with adverse consequences for child development such as fetal alcohol spectrum disorder (CDHO Advisory).
    5. Creates risks for children.
    6. Undermines mental health in children and youth.
    7. Creates difficulties for families.
    8. May be progressive, relapsing and fatal.
  2. Psychoactive substances
    1. variously affect cognitive, affective and perceptual processes of the brain and include
      1. depressants
      2. stimulants
      3. hallucinogens
      4. opioids
      5. inhalants.
    2. in recurrent use 
      1. generate physical danger in potentially hazardous situations such as
        1. driving a car 
        2. operating a machine 
      2. result in failure to fulfill major role obligations at work, school, or home, such as 
        1. repeated absences or poor work performance 
        2. absences, suspensions, or expulsions from school
        3. neglect of children or household
      3. lead to legal problems, such as arrests for substance-related disorderly conduct.

Comorbidity, complications and associated conditions

Resources consulted

Comorbid conditions are those which co-exist with substance use disorder but which are not believed to be caused by it. Complications and associated conditions are those that may have some link with it. Distinguishing among comorbid conditions, complications and associated conditions may be difficult in clinical practice. 

For substance use disorder, comorbid conditions, complications and associated conditions include

  1. Anxiety (CDHO Advisory)
  2. Dementia (CDHO Advisory)
  3. Depression (CDHO Advisory)
  4. Liver disease (CDHO Advisory)
  5. Hepatitis C (CDHO Advisory)
  6. HIV/AIDS (CDHO Advisory)

Oral health considerations

Resources consulted

Oral healthcare considerations include

  1. Requirement for rescheduling of a patient/clients’ dental hygiene appointment if s/he 
    1. appears to be 
      1. impaired 
      2. under the influence of a substance that could impair his or her judgment
    2. states that he or she has ingested a significant amount of alcohol prior to the appointment.
  2. The undermining of oral health by
    1. dry mouth and other adverse effects of 
      1. drugs or substances on which the person is dependent, such as
        Crystal Meth
      2. medications used to treat dependency, such as methadone
    2. self-neglect that often accompanies dependency
    3. cost of oral healthcare as a barrier to persons with dependency.
  3. Adverse effects on the safety of dental hygiene services because  substance use disorder may
    1. render the Procedures harmful
    2. make informed consent difficult to obtain
    3. put oral healthcare professionals at risk of 
      1. infection
      2. physical violence.
  4. Benefits to the patient/client because oral healthcare for persons with substance use disorder may
    1. improve general health as well as oral health
    2. enhance wellbeing, nutrition and social interactions. 


Sourcing medications information

  1. Adverse effect database
  2. Specialized organizations
  3. Medications considerations
    1. All medications have potential side effects whether taken alone or in combination with other prescription medications, or as over-the-counter (OTC) or herbal medications.
      Information on herbals and supplements
      US National Library of Medicine and the National Institutes of Health Medline Plus Drug Information All Herbs and Supplements
    2. Psychoactive substances are used in maintenance therapy.

Types of medications


Individual medications may be subject to important warnings, which

  1. change from time to time
  2. may affect the appropriateness, efficacy or safety of the Procedures
  3. are accessible via the links to the particular medications listed below or through the specialized organizations listed above
  4. through the links, should be viewed by dental hygienists in the course of their familiarizing themselves about a medication or combination of medications identified in the patient/client’s medical and medications history.


  1. For alcohol addiction, such as
    acamprosate (Campral®)
    disulfiram (Antabuse®
    naltrexone (ReVia®).
  2. For opioid addiction, such as
    methadone (Dolophine®, Methadose®)
    buprenorphine (Suboxone®, Subutex)
    naltrexone (ReVia®). 
  3. For mental health conditions associated with addiction, such as
    alprazolam (Alprazolam Intensol®, Xanax®)
    diazepam (Diazepam Intensol®, Valium®)
    lorazepam (Ativan®, Lorazepam Intensol®)
    triazolam (Halcion®).

Side effects of medications

See the links to the individual medications listed above.


The medical  and medications history-taking should 

  1. Focus on screening the patient/client prior to treatment decision relative to
    1. key symptoms
    2. medications considerations
    3. contraindications
    4. complications
    5. comorbidities.
  2. Explore the need for advice from the appropriate primary or specialized care provider(s).
  3. Inquire in a cautious yet unambiguous way about
    1. symptoms indicative of impairment
    2. the patient/client’s willingness to discuss his or her dependency relative to
      1. its effects on his or her oral health and self-care
      2. any history of impaired control of behaviour while he or she received 
        1. any type of healthcare 
        2. dental/dental hygiene care
      3. problems with previous dental/dental hygiene care
    3. problems with infections generally whether or not these are specifically associated with dental/dental hygiene care
    4. the patient/client’s understanding and acceptance of the need for oral healthcare
    5. medications considerations, including over-the-counter medications, herbals and supplements
    6. the patient/client’s current state of health
    7. how the patient/client’s current symptoms relate to
      1. oral health
      2. health generally
      3. recent changes in the patient/client’s condition.


Identifying and contacting the most appropriate healthcare provider(s) from whom to obtain medical or other advice pertinent to a particular patient/client

  1. Record the name of the physician/primary care provider most closely associated with the patient/client’s healthcare, and the telephone number.
  2. Obtain from the patient/client or parent/guardian written, informed consent to contact the identified physician/primary healthcare provider.
  3. Use a consent/medical consultation form, and be prepared to securely send the form to the provider.
  4. Include on the form a standardized statement of the Procedures proposed, with a request for advice on proceeding or not at the particular time, and any precautions to be observed.


Infection control

Dental hygienists are required to keep their practices current with infection control policies and procedures, especially in relation to

  1. the CDHO’s Infection Prevention and Control Guidelines (2022)
  2. relevant occupational health and safety legislative requirements.
  3. relevant public health legislative requirements.
  4. best practices or other protocols specific to the medical condition of the patient/client.


  1. If drug or alcohol dependency is of a type or extent that may affect the appropriateness or safety of scaling and root planing, including curetting surrounding tissue, the dental hygienist must not self-initiate (as per Ontario Regulation 501/107). With substance use disorder, it may be advisable for the dental hygienist to consult with the primary care physician before implementing the Procedures. (See CDHO Substance Use Disorder Fact Sheet for more information.)
  2. The dental hygienist may also postpone the Procedures pending medical advice, which is likely to be required if the patient/client 
    1. has the appearance of or acknowledges being in an impaired state
    2. is displaying symptoms or signs 
      1. of behavioural problems
      2. of serious infection
      3. attributable to comorbidity, complication or an associated condition of substance use disorder
    3. has untreated alcoholic liver disease; elective, outpatient dental hygiene care should be deferred pending assessment by a physician regarding bleeding risk, etc.
    4. has not had a medical assessment regarding possible antibiotic prophylaxis if there is a history of intravenous drug abuse
    5. not recently or ever sought and received medical advice relative to oral healthcare procedures
    6. recently changed significant medications, under medical advice or otherwise
    7. recently experienced changes in his or her medical condition such as medication or other side effects of treatment
    8. is deeply concerned about any aspect of his or her medical condition.


Dental hygienists are required to initiate emergency protocols as required by the College of Dental Hygienists of Ontario’s Standards of Practice, and as appropriate for the condition of the patient/client.

First-aid provisions and responses as required for current certification in first aid.


Subject to Ontario Regulation 9/08 Part III.1, Records, in particular S 12.1 (1) and (2)

For a patient/client with a history of substance use disorder, the dental hygienist should specifically record

  1. A summary of the medical and medications history.
  2. Any advice received from the physician/primary care provider relative to the patient/client’s condition.
  3. The decision made by the dental hygienist, with reasons.
  4. Compliance with the precautions required.
  5. All Procedure(s) used.
  6. Any advice given to the patient/client.


The patient/client is urged to alert any healthcare professional who proposes any intervention or test that he or she has a history of substance use disorder.

As appropriate, discuss 

  1. The importance of the patient/client’s
    1. self-checking the mouth regularly for suspicious signs or symptoms
    2. reporting to the appropriate healthcare provider any changes in the mouth indicative of suspicious lesions.
  2. The need for regular oral health examinations and preventive oral healthcare. 
  3. Oral self-care including information about 
    1. choice of toothpaste
    2. tooth-brushing techniques and related devices
    3. dental flossing
    4. mouth rinses
    5. management of a dry mouth. 
  4. The importance of an appropriate diet in the maintenance of oral health.
  5. For persons at an advanced stage of a disease or debilitation
    1. regimens for oral hygiene as a component of supportive care and palliative care
    2. the role of the family caregiver, with emphasis on maintaining an infection-free environment through hand-washing and, if appropriate, wearing gloves
    3. scheduling and duration of appointments to minimize stress and fatigue 
  6. Comfort level while reclining, and stress and anxiety related to the Procedures.
  7. Medication side effects such as dry mouth, and recommend treatment.
  8. Mouth ulcers and other conditions of the mouth relating to substance use disorder, comorbidities, complications or associated conditions, medications or diet.
  9. Pain management, with reference to the addictive nature of various pain relief medications. 



  1. Promotion of health through oral hygiene for persons who have  substance use disorder.
  2. Reduction of the adverse effects of substance use disorder on oral health and self-image by 
    1. encouraging the person to view oral healthcare as a positive influence on his or her 
      1. life and job or other social prospects
      2. recovery
    2. generally increasing the comfort level of the person in the course of the dental hygiene interventions 
    3. using appropriate, non-judgmental techniques of communication
    4. providing advice on scheduling and duration of appointments.
  3. Reducing the risk that oral healthcare needs are unmet.


  1. Causing or failing to respond to appropriately to inappropriate, harmful or dangerous behaviour on the part of the person.
  2. Performing the Procedures at an inappropriate time, such as 
    1. when the person is in a disturbed mental state, is impaired or exhibits signs of insufficient control over behaviour 
    2. when the person  is suffering from a serious infection
    3. in the presence of complications for which prior medical advice is required
    4. in the presence of acute oral infection without prior medical advice.
  3. Disturbing the normal dietary and medications routine of the person.
  4. Inappropriate management of pain or medication in ways that encourage addiction or undermine the person’s treatment program.
  5. Unnecessarily causing or encouraging avoidance of the Procedures.






2010-07-15; 2018-12-02; 2023-04-05


College of Dental Hygienists of Ontario, regulatory body
Greyhead Associates, medical information service specialists


College of Dental Hygienists of Ontario


College of Dental Hygienists of Ontario, Practice Advisors


Dr Gordon Atherley
O StJ , MB ChB, DIH, MD, MFCM (Royal College of Physicians, UK), FFOM (Royal College of Physicians, UK), FACOM (American College of Occupational Medicine), LLD (hc), FRSA

Dr Kevin Glasgow

Lisa Taylor

Elaine Powell

Giulia Galloro

Carolle Lepage


The College of Dental Hygienists of Ontario gratefully acknowledges the Template of Guideline Attributes, on which this advisory is modelled, of The National Guideline Clearinghouse™ (NGC), sponsored by the Agency for Healthcare Research and Quality (AHRQ), U.S. Department of Health and Human Services.

Denise Lalande
Final layout and proofreading

© 2009, 2018, 2023 College of Dental Hygienists of Ontario


1 Persons includes young persons and children.
2 In contradistinction to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-4, published in 1994), DSM-5 (published in 2013) combines the DSM-4 categories of substance abuse and substance dependence into “substance use disorder” measured on a continuum from mild to severe.
3 “Alcohol misuse” and “substance misuse” are terms that are roughly equivalent to “alcohol abuse” and “substance abuse”. However, “abuse” is increasingly being avoided by healthcare professionals due to its negative connotation.
4 While Canada expanded cannabis/marijuana legalization in 2018 to include recreational use, much of the consumer supply still occurs via illegal sources and channels. Adulteration of illicitly obtained cannabis/marijuana with other drugs and chemicals is a concern, along with variability in tetrahydrocannabinol (THC, the psychoactive component) potency.
5 See footnote 4.