Lesson Notes By Weeks and Term v4 - SHS 3
BIOSAFETY
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BIOSAFETY
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Subject: Biomedical Science
Class: SHS 3
Term: 2nd Term
Week: 9
Grade code: 3.1.2.LI.2
Strand code: 1
Sub-strand code: 2
Content standard code: 3.1.2.CS.1
Indicator code: 3.1.2.LI.2
Theme: BIOMEDICAL SCIENCE IN SOCIETY
Subtheme: BIOSAFETY
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In our communities, from the polyclinic in Madina to the teaching hospital in Korle Bu, and even in our own school laboratory, various types of waste are produced daily. We cannot simply mix a used syringe with a paper towel or a chemical with food leftovers. Improper disposal of laboratory and medical waste poses a severe threat to our health, our environment, and the safety of sanitation workers (our "borla" men and women). This lesson will equip you with the essential knowledge to handle hazardous waste safely and responsibly, a critical skill for any future scientist, healthcare professional, or informed citizen.
This section breaks down the essential information you need to understand and apply the principles of safe waste disposal. A. Fundamental Definitions Hazardous Waste: This is any waste material that can cause harm to humans, animals, or the environment. It can be infectious (carrying germs), toxic (poisonous), sharp (can cause cuts), or chemically reactive. In a lab, this includes things like used needles, blood-soaked cotton, bacterial cultures, and expired chemicals. Waste Stream: This is the entire journey of a specific type of waste from where it is created (e.g., your lab bench) to its final disposal (e.g., an incinerator or a special landfill). To manage waste safely, we must separate it at the source into different streams. B. The Main Laboratory Waste Streams and Their Colour Codes
In Ghana and around the world, a colour-coding system is used to make waste segregation simple and effective. It helps everyone, from the scientist to the cleaner, to know exactly where to put different types of waste. General Waste (Non-Hazardous) Colour Code: Black bin or bag. Description: This is waste that is similar to what you would produce in an office or at home. It is not contaminated with biological or chemical hazards. Examples: Paper towels used for drying clean hands. Packaging from new equipment (e.g., cardboard boxes, plastic wrappers). Office paper. Used pens. Disposal Procedure: Simply place these items in the designated black bin. This waste usually ends up in a general municipal landfill. Infectious Waste (Biohazardous) Colour Code: Yellow bin or bag, marked with the biohazard symbol (☣). Description: This is waste that is contaminated with blood, body fluids, or other potentially infectious materials (like bacteria or viruses). It can spread diseases if not handled correctly. Examples: Blood-soaked cotton wool or gauze. Used gloves, aprons, or masks from a procedure. Petri dishes with microbial cultures. Swabs used to take samples from patients. Human or animal tissues. Disposal Procedure: Carefully place the item into the yellow biohazard bag. Avoid touching the outside of the bag with contaminated gloves. When the bag is three-quarters (¾) full, it should be securely tied or sealed. This waste must be treated before final disposal, often by incineration (burning at very high temperatures) or autoclaving (sterilising with high-pressure steam). Sharps Waste Colour Code: Yellow puncture-proof container, marked with the biohazard symbol (☣). Description: This category includes any item that can pierce or cut the skin. The danger is twofold: a physical injury and the potential infection from the contamination on the sharp object. Examples: Hypodermic needles and syringes. Lancets (used for finger-pricking). Scalpel blades. Broken glass slides or test tubes (especially if contaminated). Disposal Procedure: Crucial Rule: NEVER recap a used needle. This is a common cause of accidental needlestick injuries. Immediately after use, drop the sharp item (e.g., needle and syringe) into the rigid, yellow sharps container. The container must be puncture-proof and have a lid that allows items to be dropped in but not easily removed. When the container is three-quarters (¾) full, it must be sealed permanently. Like infectious waste, sealed sharps containers are usually incinerated. Chemical and Pharmaceutical Waste Colour Code: Brown bin or container. Description: This stream is for hazardous chemicals and expired medicines. They can be toxic, flammable, or corrosive. Pouring them down the sink or putting them in general waste can pollute water and soil. Examples: Expired laboratory reagents (e.g., old acids, bases, solvents). Unused or expired drugs/medicines. Contaminated chemical containers. Waste from chemical analysis (e.g., heavy metal solutions). Disposal Procedure: Place the chemical waste in the designated brown container. Ensure different types of chemicals are not mixed if they can react dangerously. This waste requires specialised treatment, such as chemical neutralisation or disposal at a secure hazardous waste facility.
Summary Table:
| Waste Type | Colour Code | Container Type | Examples | Final Disposal Method | | ------------------- | ----------- | ------------------------------ | ------------------------------------------------ | ------------------------- | | General Waste | Black | Standard Bin / Bag | Paper towels, packaging, office supplies | Municipal Landfill | | Infectious Waste | Yellow | Leak-proof Bag / Bin (☣) | Soiled gloves, cotton, bacterial cultures | Incineration / Autoclaving | | Sharps Waste | Yellow | Puncture-proof Container (☣) | Needles, scalpels, broken contaminated glass | Incineration | | Chemical Waste | Brown | Chemical-resistant Container | Expired reagents, solvents, old medicines | Specialised Treatment |