Substance Use, Workplace Health, and Genomics Insights

Posted on Aug 16, 2025 in Animal Science and Health

Substance Use Disorders: Understanding & Management

Key Definitions in Substance Use

  • Substance Use Disorder (SUD): Treatable, chronic diseases (mental disorder) characterized by a problematic pattern of use of a substance or substances leading to impairments in health and social function, and continued use despite harm.
  • Misuse: Any substance use that is high or inappropriate for a health or social problem.
  • Dependence: Physiological adaptation leading to withdrawal symptoms upon cessation.
  • Addiction: Loss of control over urges to take a substance despite negative consequences.
  • Tolerance: The body’s adaptation to a substance, requiring more or different amounts to achieve the desired effect (diminished response).

Examples include alcohol, prescription drugs, tobacco, and psychoactive substances (e.g., methamphetamine, cannabis).

World Health Organization (WHO) Objectives:

  • Ensure access to needed controlled medications.
  • Prevent and manage harms associated with drug use.
  • Provide universal access to effective treatment and care for people with drug use disorders.

Methamphetamine: History, Risks, & Control

Methamphetamine (Meth): Amphetamine derivative (1887), Methamphetamine (1893). Used by Germans in WWII. 1950s: Used for obesity. 1970s: Controlled in the US. 1980s: Ephedrine controlled, other precursors like pseudoephedrine used. 1990s: Widespread use.

Methamphetamine: Effects and Risks

  • Euphoria, increased energy, and alertness.
  • Chronic mood and cognitive changes: irritability, aggression, panic, hallucinations, memory impairment.
  • Increased risk of early mortality and suicide attempts.
  • Cardiovascular complications: arrhythmia, myocardial infarction, heart failure, stroke.

Methamphetamine: Legal Status & Control

Legal Status: Class A controlled substance; illegal to consume outside of medical prescription.

Methamphetamine: Screening, Diagnosis, Management

  • Screening: Prompted by signs of presentation, history, and physical examination.
  • Testing: Saliva (up to 48 hours), Urine (up to 7 days), Hair (up to 90 days).
  • Diagnosis: DSM-5 diagnostic criteria.
  • Management: Psychosocial interventions (e.g., Motivational Interviewing, Drug Counseling, Cognitive-Behavioral Therapy).

Alcohol Use Disorder: Impact & Control

Alcohol Use Disorder: Accounts for 5.1% of Disability-Adjusted Life Years (DALYs).

Alcohol: Consumption Control Approaches

Reduce population-level consumption by:

  • Increasing alcohol taxes.
  • Increasing minimum alcohol retail price.
  • Increasing alcohol drinking age.
  • Decreasing hours of sale at night.
  • Implementing advertising restrictions.

Alcohol: Injury Control & Legal Limits

Reduce alcohol-related road injuries by:

  • Publicity campaigns.
  • Enforcement of drink-driving laws.
  • Random breath testing.
  • Ignition interlock devices (e.g., EU countries: Belgium, Denmark, Finland, France, Netherlands, Poland, Sweden, Austria).
  • Legal Limit: Blood Alcohol Content (BAC) > 30 mcg alcohol/100mL breath or > 80 mg alcohol/100ml blood can lead to drink-driving charges. Maximum fine of SGD 10,000 and 1 year jail.
  • Reduce alcohol venue trading hours and enhance venue security.

Recommended Limits: 2 standard drinks/day for men, 1 standard drink/day for women (men typically have lower body fat percentage and higher alcohol dehydrogenase enzyme activity).

Alcohol: Screening, Diagnosis, Management

  • Screening: Alcohol history, physical examination for potential comorbidities and complications, laboratory investigations.
  • Diagnosis: DSM-5 criteria.
  • Management: Education on laws and limits, psychosocial interventions, referral to community or psychiatric services.

Opioid Use: Effects, Overdose, & Prevention

Opioids: Act on opioid receptors, causing:

  • Analgesia (pain relief).
  • Cough suppression.
  • Sedation.
  • Respiratory depression.
  • Euphoria.

Opioids: Mechanism & Overdose Symptoms

Overdose Symptoms:

  • Constricted pupils.
  • Breathing difficulty.
  • Unconsciousness.
  • May have seizures.

Overdose Management: Naloxone (opioid antagonist), supportive care (to improve breathing and ventilation).

Opioids: Withdrawal & Management

Withdrawal Symptoms:

  • Sweating.
  • Joint aches.
  • Runny nose or tearing.
  • Tremor.
  • Restlessness.
  • Anxiety or irritability.

Withdrawal Management: Naloxone + Buprenorphine, symptom management.

Opioids: Prevention & Legal Status

Prevention Strategies:

  • Increase availability of treatment.
  • Reduce irrational prescribing.
  • Monitor dispensing and prescribing practices.
  • Limit over-the-counter (OTC) sales.

Legal Status: Controlled drug. License required to import, store, wholesale, export, or manufacture. HSA approval required for personal import. Codeine sales are restricted.

Prescribing Guidelines: Not first-line treatment. Identify risk/patient factors before starting. Monitor patients. Educate patients.

Occupational Health: Workplace Well-being

The Impact of Work on Health

Work can lead to injuries, obvious or hidden, and incurable diseases, impacting health and decreasing productivity, affecting individuals and communities.

Occupational Health (OCH) aims to identify diseases and hazards, prevent injuries, and promote health and a productive workforce.

Evolution of Occupational Health Practices

  • Industry 1.0 (Mechanization, Steam Power): Little Workplace Safety and Health (WSH) regulation.
  • Industry 2.0 (Mass Production, Electricity): New WSH laws, examination of causality between work exposure and disease.
  • Industry 3.0 (Computers): Rising Non-Communicable Diseases (NCDs), integration of Work Health promotion with WSH.
  • Industry 4.0 (IoT, Networks): Changing work conditions.

Occupational Health in Singapore

70% of Singapore’s population is in the workforce.

Singapore Workforce & Health Challenges

  • Workforce challenges: Shrinking due to declining fertility rate, rapidly aging population and workforce.
  • Health challenges: Worse off than the general population (e.g., increase in obesity from 8% to 10% across age groups and males).
  • Policy: Cutting back on foreign manpower.

Key Legislation & Health Statistics

  • Workplace Safety and Health Act (WSHA) 2006
  • Work Injury Compensation Act (WICA) 2019

National Health Initiatives and Statistics:

  • War on Diabetes declared (April 13, 2016): Associated risks include blindness, kidney failure, heart attack, stroke, amputation.
  • Hypertension: 35.5% (half undiagnosed).
  • Hyperlipidemia: 39.1% (half undiagnosed).
  • Obesity: Increased to 10%.
  • Diabetes: Increased to 9.5%.
  • Binge Drinking: Increased to 10.5%.
  • Disease Screening: Decreased to 63%.

Genomics & Precision Medicine: Future of Health

Fundamentals of Genomics

  • DNA: Adenine, Guanine, Cytosine, Thymine.
  • RNA: Guanine, Cytosine, Adenine, Uracil.

Genome Sizes (approximate base pairs): Virus (1.7e5 bp), Bacteria (4.6e6 bp), Fruit Fly (1.3e8 bp), Human (3.2e9 bp), Canopy (1.5e11 bp).

Genomics: The study of the genome, the complete set of genes, and their interaction with the environment.

Cystic Fibrosis: A Monogenic Disease Example

  • Characterized by sticky mucus buildup in lungs and digestive system.
  • Leads to difficulty breathing and increased risk of infection.
  • Caused by a recessive mutation in the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene.
  • Monogenic diseases are distinct from those primarily due to environmental factors.

Precision Medicine: Tailoring Healthcare

Precision Medicine considers:

  • Individual variations in genetics/genomes.
  • Environmental factors.
  • Lifestyle factors.

Aims to more accurately predict which treatment or prevention strategy will work best for different groups of people.

Hopes to achieve:

  • Predict health conditions.
  • Faster diagnosis.
  • Optimized treatment: Receive the right treatment at the right time, improving efficacy and reducing side effects.
  • Novel treatments: Understand mechanisms of conditions to inform development of new drugs and therapies.

Pharmacogenomics: Personalized Drug Treatment

Pharmacogenomics: The use of genetic and genomic information to tailor pharmaceutical treatment.

Example: Epilepsy (50 million worldwide, 3-5/1000 in Singapore). Carbamazepine (CBZ) used to control seizures, but may cause lethal Stevens-Johnson Syndrome (SJS) in some individuals based on genetic predisposition.

Pathogen Genomic Epidemiology

Combines pathogen genomic and epidemiological data to control and limit the spread of infectious diseases.

Example: Tuberculosis (TB) outbreak in Bukit Merah.