LABMAN

• Hierarchy of controls


  • Elimination
  • Substitution
  • Engineering controls
  • Administrative controls
  • PPE
• Elimination


  Removes the hazard at the source, preferred solution to protect workers because no exposure can occur
• Substitution


  Using a safer alternative to the source of the hazard, effective substitutes reduce the potential for harmful effects and do not create new risks
• Engineering controls


  Reduce or prevent hazards from coming into contact with workers, can include modifying equipment or the workspace, using protective barriers, ventilation, and more, can cost more than administrative controls or PPE but long-term operating costs tend to be lower, especially when protecting multiple workers, can save money in other areas of the work process or facility operation
• Administrative controls


  Establish work practices that reduce the duration, frequency, or intensity of exposure to hazards, including work process training, job rotation, ensuring adequate rest breaks, limiting access to hazardous areas or machinery, adjusting line speeds
• PPE


  Equipment worn to minimize exposure to hazards, when employees use PPE, employers should implement a PPE program which should address workplace hazards assessment, PPE selection and use, inspection and replacement of damaged or worn-out PPE, employee training, and program monitoring for continued effectiveness, might seem to be less expensive than other controls, but can be costly over time (e.g. multiple workers using PPE on a daily basis)
• Biological hazards are disease producing agents (pathogens) that can be transmitted to individuals through various routes of exposure (modes of transmission)
• Exposure to these hazards may result in acute or chronic health conditions
• Examples of pathogens and common modes of transmission


  • Blood and body fluids: Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), Human Immunodeficiency Virus (HIV)
  • Fecal-oral: Hepatitis A Virus (HAV), Hepatitis E Virus (HEV)
  • Contact: Herpes Simplex Viruses (HSV), Human Papilloma Virus (HPV), Cytomegalovirus (CMV), Vancomycin Resistant Enterococcus (VRE), Methicillin Resistant Staphylococcus Aureus (MRSA), Clostridium difficile (C. difficile)
  • Small particle aerosol (airborne): Mycobacterium Tuberculosis
  • More than one mode: contact, and/or droplet spray: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Herpes Zoster Virus (HZV), Influenza virus (Flu), Measles (Rubeola virus)
• Chain of infection


  • Infectious agents
  • Reservoir / source
  • Portal of exit
  • Modes of transmission
  • Portal of entry
  • Susceptible host
• The circles contained within the biohazard symbol represent the chain of infection: Agent, Host, and Transmission
• Biosafety levels


  • BSL 1: Agents that have no known potential for infecting healthy people
  • BSL 2: Microorganisms associated with Human diseases that are rarely serious and for which preventive or therapeutic interventions are often available
  • BSL 3 (with risk-based enhancements): Material that may contain viruses not normally encountered in a clinical laboratory and mycobacteria
  • BSL 4: Dangerous and exotic agents that pose a higher risk of aerosol transmitted laboratory infections and life-threatening disease for which effective treatments are limited
• Handwashing


  Most important means of preventing the spread of infection, if hands are visibly soiled, wash hands with soap and water for 1-2 mins, if hands are not visibly soiled, wash hands for at least 30 secs. or use alcohol based hand cleaners, CDC Guidelines: During handwashing, thoroughly clean between your fingers and under your fingernails for at least 20 secs. And rinse your hands in a downward position to prevent recontamination
• Personal protective equipment (PPE)


  • Laboratory gown: Worn to protect the clothing and skin of health, protect workers from contamination, should be put on first
  • Masks, goggles, face shields: Worn to protect against splashes and inhalation of droplets containing pathogens from infective patients
  • Gloves: Worn to protect healthcare workers from contamination by patient body substances, proper removal: 1. Grasp wrist part of one glove with opposite hand, 2. Pull glove inside out and off hand, 3. Place recently removed glove in gloved hand, 4. Slip fingers of non-gloved hand under wrist of gloved hand and pull second glove inside out, 5. Drop gloves in proper receptacle
• Donning and doffing of PPE


  • Donning: 1. Gown should be put on first, 2. Mask should cover both nose and mouth, 3. Gloves should be pulled over the gown cuff
  • Doffing: 1. Gloves are removed first, 2. Gown should be pulled from the shoulders towards the hands, 3. Mask should be removed
• Decontamination of body fluid spills


  5.25% NaOCL or 10% chlorine bleach (1:10 dilution), recommended contact time is 15 minutes
• Biosafety Cabinets (BSCs) are enclosed workspaces with a ventilated hood that is designed to contain pathogenic microorganisms during microbiological processes

  
• The primary purpose of biosafety cabinets is to protect the laboratory personnel and the environment from the pathogenic microorganism as aerosols might be formed during the processing of such microorganisms

  
• Biosafety cabinets are only used for certain risk group organisms and for processes that might result in aerosol formation

  
• These cabinets are provided with HEPA-filters that decontaminate the air moving out of the cabinet
• Biosafety cabinets might be confused with the laminar hood as both of these pieces of equipment work as enclosed workspaces, but, laminar hood only provides protection to the sample and not to the personnel and the environment, whereas biosafety cabinets protect all three
• Class I and II Biosafety cabinets are used for Biosafety levels I and II but, when used correctly in conjunction with useful microbiological techniques, these provide an effective containment system for safe manipulation of moderate and high-risk microorganisms

  
• Class III BSCs are most suitable for work with hazardous agents that require Biosafety Level 3 or 4
• Class I biosafety cabinet


  The most basic biosafety cabinet that provides protection to the environment and the laboratory personnel, but doesn't provide protection to the product as the unsterilized room air is drawn over the work surface, typically used to either enclose specific equipment like centrifuges or for procedures like aerating cultures that might potentially generate aerosols, can be either ducted (connected to the building exhaust system) or unducted (recirculating filtered exhaust back into the laboratory), room air is drawn in through the opening that also allows the entry of the operator's arm during work, the air inside the cabinet then takes in the aerosol particles that may have been generated and moves it away from the operator towards the HEPA filter, the air moving out of the cabinet is sterilized via the HEPA filters before its discharge to the environment

  
• Class II biosafety cabinet


  Provide both protection of the samples and the environment since makeup air is also HEPA filtered, the principle of operation involves a fan mounted in the top of the cabinet that draws a curtain of sterile air over the workstation where the biological products are being handled, the air then moves underneath the work station and back up to the top of the cabinet before passing through the HEPA filters, the exhaust that moves out of the facility consists of air being drawn into the front of the cabinet underneath the work surface, the air drawn in acts as a barrier against the potentially contaminated air coming back out to the operator, Class II BSCs are further divided into five types depending on the exhaust system and the mechanism of work (recirculation of the exhaust air): Type A1, Type A2, Type B1, Type B2, and Type C1
• Type A1 biosafety cabinet


  Have a minimum inflow velocity of 75ft/min where the contaminated divided just above the work station and mixes with the inflow air, the mixed air is then drawn through a duct network so that it reaches the back of the cabinet, after this, air might be either recirculated after passing through the HEPA filters or exhausted out of the cabinet, also through a HEPA filter, this type of cabinet is not as widely used as it is not safe to work with hazardous chemical substances
• Type A2 biosafety cabinet


  Have a minimum inflow velocity of 100ft/min
• Class II Biological Safety Cabinets (BSCs)


  • Further divided into five types depending on the exhaust system and the mechanism of work (recirculation of the exhaust air): Type A1, Type A2, Type B1, Type B2, and Type C1
• Type A1 cabinets


  1. Minimum inflow velocity of 75ft/min

  2. Contaminated air divided just above the work station and mixes with the inflow air

  3. Mixed air drawn through a duct network to the back of the cabinet

  4. Air might be either recirculated after passing through the HEPA filters or exhausted out of the cabinet, also through a HEPA filter
• Type A1 cabinets are not as widely used as they are not safe to work with hazardous chemical substances
• Type A2 cabinets


  1. Minimum inflow velocity of 100 ft/min

  2. Air enters the chamber through the front aperture, providing operator protection

  3. Inflow air mixes with the downflow air (from the top of the cabinet) and enters the front intake grille

  4. 60% to 70% of the contaminated air is recycled and pushed back into the workstation in the chamber through the downflow HEPA filter, while the remaining 30% to 40% is exhausted through the exhaust HEPA filter

  5. If hazardous, volatile chemicals are to be used, exhaust must be released into the atmosphere through the direct duct system
• Type A2 cabinets are also not extensively used because of the chances of the release of hazardous chemicals into the environment
• Type B1 cabinets


  1. Divide the airflow so that the contaminated air is directed towards the exhaust system while the air between the operator and the workstation mixes with the inflow and is recirculated

  2. Exhaust air dispersed out of the facility should be passed through the HEPA filters

  3. 30% of the air is recirculated, whereas the remaining 70% is exhausted out of the facility
• Type B2 cabinets


  1. Air is drawn in from the front opening creating an air barrier that protects the operator

  2. Air is also drawn in from an opening at the top of the cabinet that supplies the downflow of air in the cabinet

  3. 100% of the air is exhausted through a dedicated duct system with an exhaust fan motor

  4. All of the contaminated airflow (100%) is externally exhausted, with no recirculation within the BSC
• Type B2 cabinets


  • Best to be used for tasks involving the release of chemical vapors
  • Expensive, and their use is limited to toxicology laboratories where protection against hazardous chemicals is imperative
• Type C1 cabinets


  1. Use the single-pass airflow system where the cabinets move the air by mixing it with the downflow air separated into columns for recirculation

  2. The air above the workstation is drawn with a second fan which moves the contaminated air out through the exhaust system with a HEPA filter
• Type C cabinets


  • Different from Type A cabinets as they use a single pass airflow mechanism where the air is not circulated
  • Different from Type B cabinets in that they don't require a dedicated ducted exhaust system, can work for an extended duration to increase operator protection in the case of exhaust failure, and can even run without the exhaust at all
• Class III cabinets


  • Leak-tight, totally enclosed but ventilated cabinets, where all air that either enters or leaves through the facility pass through a HEPA filter
  • Provided with rubber gloves attached to the system to be used during operations in the cabinet
  • Have a transfer chamber that facilitates the sterilization of materials before they leave the glove box
  • Exhaust air is treated with double HEPA filters or HEPA filters in combination with incineration
  • Can be used for all four Biosafety levels (1, 2, 3, and 4), but are most important for the manipulation of biological materials in the Biosafety level 4
  • Mostly custom-built for specific laboratories with lab equipment built inside the chamber
• All of the structural and design features of Class III cabinets provide maximum protection to the operator, the environment, and the sample against the high-risk group 4 pathogenic organisms

  
• Hazard Classification


  • Corrosion
  • Skull and Crossbones
  • Health Hazard
  • Exclamation Mark
  • Environment
  • Flame
  • Explosive
  • Corrosion
  • Flame Over Circle
  • Gas Cylinder