Question 4 of 7: Biological Hazards

Question 4: Biological Hazards (20 marks: 7/7/6)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Agents and Sources of Biological Hazards

• Agents: bacteria, viruses, fungi (moulds/yeasts), parasites, and their toxins; also biological materials such as blood and other bodily fluids.
• Sources: infected people or animals; contaminated water, air, food or surfaces; sewage and waste; laboratory cultures; agricultural products, plants and organic dusts; healthcare settings (needles, specimens); HVAC systems harbouring mould/legionella.

(ii) Broad Examples of Biohazards

• Bloodborne pathogens — hepatitis B/C, HIV (healthcare, first aid).
• Airborne infections — tuberculosis, influenza, Legionnaires' disease.
• Zoonoses — diseases from animals (rabies, anthrax) in agriculture/veterinary work.
• Moulds and organic dusts — causing allergies, asthma, "farmer's lung."
• Contaminated water/waste — sewage-related infections.
• Laboratory cultures of pathogenic microorganisms.

(iii) Classification of Biohazards (Risk/Biosafety Levels)

• Group/Level 1 — agents unlikely to cause disease in healthy humans (minimal risk).
• Group/Level 2 — can cause disease but treatment/preventive measures exist and spread is limited (moderate risk).
• Group/Level 3 — serious disease, may spread; treatment/prevention usually available (high individual risk, limited community risk).
• Group/Level 4 — serious disease, readily transmitted, no reliable treatment/prevention (high individual and community risk).
• Each level dictates progressively stricter containment (biosafety level BSL-1 to BSL-4): facilities, practices and PPE.
• Canadian frame — under the Human Pathogens and Toxins Act and the Public Health Agency of Canada's Canadian Biosafety Standard, agents are assigned to Risk Groups 1–4 and handled in facilities of matching Containment Level CL1–CL4 (the Canadian counterpart of BSL-1 to BSL-4); WHMIS also classifies "biohazardous infectious materials" as a health hazard.