Study Notes on Biological Safety and Chemical Hazards

Biological Safety

Engineering Controls

  • Sharps Containers

    • Description: Puncture-resistant containers designed for safe disposal of needles, scalpels, and other sharp objects potentially contaminated with biological materials.

  • Biohazard Containers

    • Description: Specialized receptacles for collecting, storing, and disposing of biohazardous waste; clearly marked with universal biohazard symbols.

Engineering Controls Safety Devices

  • Engineered Tools

    • Definition: Tools designed to minimize exposure risk, including:

    • Self-sheathing needles

    • Safety scalpels

    • Other equipment that prevents accidental injuries.

  • Splash Guards

    • Definition: Physical barriers that protect laboratory personnel from splashes, splatters, and aerosols generated during procedures involving potentially infectious materials.

Workplace Practice Controls

  • Engage Safety Needles ASAP

    • Protocol:

    • Activate safety features on needles immediately after use to prevent needlestick injuries and potential exposure to bloodborne pathogens.

    • Never recap needles using two hands.

    • Use a one-handed scoop technique for recapping if absolutely necessary.

    • Activate safety mechanisms before removing hands from the device.

  • Dispose of Sharps ASAP

    • Recommendation: Promptly place used sharps into designated containers to minimize handling and reduce injury risk.

  • Clean Up Spills with Disinfectants

    • Protocols:

    • Immediately contain and treat biological spills with appropriate disinfectants to neutralize potential pathogens.

    • Follow established protocols based on spill type and size:

      • Use EPA-registered disinfectants suitable for the biological agent.

      • Work from the outside of the spill towards the center.

      • Allow adequate contact time for disinfectant to be effective.

      • Document all incidents according to laboratory policy.

Biohazard Symbols

  • Standard Biohazard

    • Definition: The universal symbol for biological hazards indicating the presence of infectious agents or biohazardous materials that could risk human health or the environment.

  • Biohazard Waste

    • Purpose: Specifically designates containers and areas for the collection, storage, and disposal of contaminated materials requiring special handling procedures.

  • Laboratory Biohazard

    • Purpose: Placed at laboratory entrances to alert personnel and visitors about the biosafety level and specific hazards present within the space.

Evolution of Biological Safety Guidelines

  • Initial Period

    • Observation: In the early 20th century, laboratory safety was often neglected. Examples include:

    • Scientists like Marie Curie working without adequate radiation safety measures, leading to severe health consequences.

    • Early microbiologists frequently worked without gloves, leading to common laboratory-acquired infections.

  • Mid 20th Century Developments

    • Context: The rise of microbiology and virology underscored the need for safer practices.

    • Emergence: The first formal biosafety guidelines were established in the 1940s-1950s, focusing on:

    • Preventing laboratory-acquired infections.

    • Protecting public health.

    • Development of early biological containment equipment, including primitive biosafety cabinets.

  • Asilomar Conference (1975)

    • Significance: A pivotal moment where scientists voluntarily agreed on guidelines for safe genetic engineering research, balancing innovation with safety.

  • Legislative Changes (1908-1990)

    • Introduction of the Occupational Safety and Health Administration (OSHA) Chemical Hygiene Plan and the Bloodborne Pathogen Standard, improving lab safety standards significantly.

    • The HIV/AIDS epidemic in the 1980s highlighted the importance of universal precautions when handling human specimens, resulting in more comprehensive protocols for potentially infectious materials.

  • Modern Developments (2000 to Present)

    • Focus: Modern biosafety guidelines emphasize a risk-based approach.

    • Reference: The World Health Organization’s Laboratory Biosafety Manual provides a framework for assessing and managing laboratory risks, ensuring safety measures are tailored to specific biological agent risks.

Biological Safety Cabinets & Fume Hoods

  • Differences Between BSCs and Fume Hoods

    • Importance: Understanding the distinct purposes of biological safety cabinets (BSCs) and fume hoods is essential for laboratory safety.

    • Protection:

    • BSCs: Designed to protect the worker and environment from human pathogens and potentially infectious agents.

    • Fume Hoods: Designed to reduce or eliminate exposure to dust, mist, and other aerosols. Both types address aerosol hazards but do so in different contexts.

Biological Safety Cabinets (BSC)

  • Purpose: Protects user, environment, and product from biological hazards like bacteria and viruses.

  • Key Features:

    • Utilizes HEPA filters to trap airborne biological particles.

    • Maintains a sterile work environment.

    • Available in Class I, II, and III types, with airflow filtration and recirculation or exhaust dependent on class.

  • Best Uses: Microbiology, cell culture, handling infectious agents.

Fume Hoods

  • Purpose: Protects user and environment from hazardous chemical vapors, gases, and dust.

  • Key Features:

    • Pulls air away from the user to exhaust it outside.

    • May be ducted or ductless (with carbon filters).

    • Does not have HEPA filtration, thus not sterile.

  • Best Uses: Acid/base reactions, solvent evaporation, toxic or volatile chemicals.

Biosafety Cabinets Classifications

  • Class I Cabinets:

    • Characteristics: Basic design providing personnel and environmental protection but no product protection.

    • Usage: For low to moderate risk agents.

  • Class II Cabinets:

    • Characteristics: Most frequently used; provides personnel, environmental, and product protection.

  • Class III Cabinets:

    • Description: Maximum containment cabinets used for Level 4 pathogens; entirely enclosed with sealed glove ports for manipulation.

Class I Biosafety Cabinet

  • Characteristics: Provides protection for the operator and HEPA filters exhaust air.

  • Limitations: Provides no protection for samples as room air flows directly over the work surface.

Class II Biosafety Cabinet

  • Features:

    • Intended for microorganisms from levels 2, 3, and 4.

    • Ensures complete product protection through HEPA-filtered laminar airflow.

    • Not suitable for flammable or toxic chemicals due to air recirculation.

Class III Biosafety Cabinet

  • Description: Maximum protection, entirely ducted outside.

    • 30% air recirculated, 70% exhaust.

    • Can use minimal amounts of toxic or volatile chemicals under strict protocols.

Guidelines for Using BSC

  • Preparation:

    1. Adjust working position to prevent contaminated air from entering the breathing zone.

    2. Purge cabinet air for at least five minutes before beginning work.

    3. Disinfect all interior surfaces before use.

  • Setup:

    • Organize materials to lessen entrance and exit movements disrupting airflow.

    • Establish zones (clean, work, and dirty).

  • During Work:

    • Ensure proper personal protective equipment (PPE) is worn.

    • Maximize the protective effect by staying away from the opening.

    • Stabilization is essential after adjusting arm positions to maintain airflow.

  • Best Practices:

    • Avoid open flames, maintain airflow, and work from clean to dirty areas to prevent cross-contamination.

  • Spill Management: Contain spills immediately, sterilize all surfaces.

Decontamination Procedures

  • Post-Work:

    1. Dispose of contaminated materials properly.

    2. Remove all items from the cabinet.

    3. Disinfect surfaces thoroughly.

    4. Use UV light if necessary after cleaning.

  • Final Steps: Allow cabinet to purge for an additional five minutes after decontamination to ensure no airborne contaminants remain.

Types of Fume Hoods

  • Ducted: Vents air outside.

  • Ductless: Uses filters; good for light chemical use.

  • Walk-in: For bulky equipment.

  • Specialty Hoods: Designed for specific hazards.

Fume Hood Operation

  1. Air intake through front sash for protection.

  2. Contaminants captured by airflow.

  3. Clean air released post-filtration or exhaust.

Fume Hood Safety Tips

  • Keep sash low to serve as a barrier.

  • Regular checks of airflow monitors to ensure proper function.

  • Avoid clutter and maintain material placement for proper air circulation.

Certification and Maintenance

  • Annual certification required for biosafety cabinets and regular maintenance checks. Documentation should be maintained for all activities.

Chemical Hazards

  • Importance: Chemical hazards present challenges. Knowing proper handling and storage is essential for safety in laboratory environments.

Oxidizers

  • Hazards: Produce oxygen, accelerates fires.

  • Examples: Nitric acid, oxygen, hydrogen peroxide.

  • Safety Precautions:

    • Store away from flammable materials.

    • Maintain tight closures.

Organic Peroxides

  • Hazards: Highly reactive and unstable compounds, serious explosion risks.

  • Examples: Hydrogen peroxide, benzoyl peroxide.

Explosives

  • Definition: Substances undergoing rapid transformation releasing energy.

  • Regulatory Requirements: Licenses, special storage needed.

Compressed Gas

  • Hazards: High-pressure risks, potential flammability.

  • Classification: Flammable, non-flammable, toxic gases etc.

Flammable Solids

  • Characteristics: Materials prone to ignition.

  • Examples: Alkali metals, phosphorus.

Flammable & Combustible Liquids

  • Definition: Liquids with ignition potential.

  • Key Measures: Store properly in audited storage cabinets.

Transporting Chemicals Safely

  1. Use secondary containment.

  2. Select appropriate containers to ensure safety.

  3. Plan the route for transport carefully.

Chemical Storage Principles

  • Separation Requirements: Keep acids, oxidizers, bases separate.

  • Storage Cabinet Requirements: Rated cabinets designed for specific hazards.

NFPA 704 Labeling System

  • Fire Diamond: Standardized hazard communication system.

    • Colors indicate:

      • Blue: Health hazard.

      • Yellow: Instability.

      • Red: Fire hazard.

      • White: Specific risks.

Chemical Safety Entry Routes

  • Absorption through respiratory tract: Ingestion, injection, dermal contact.

  • Ocular Exposure: Risks presented to the eyes; potential for severe damage.

  • Inhalation Exposure: Common pathway for chemical exposure leading to various health issues.

  • Ingestion Exposure: Preventable with good laboratory practices.

  • Dermal Absorption: Underestimated risk; proper PPE necessary.

WHMIS: Workplace Hazardous Material Information System

  • Definition & Purpose: Canada's hazard communication standard for chemicals; provides a framework for communicating hazards.

  • Components of WHMIS:

    • Supplier Responsibilities: Classification, SDS creation, labeling.

    • Employer Responsibilities: Implementing and maintaining safety protocols and training.

    • Worker Responsibilities: Active participation in safety training and adherence to safety procedures.

  • GHS Overview: Globally Harmonized System introduced to standardize chemical classification and hazard communication.

WHMIS 2015 Components

  • Pictograms: Communicate hazards – updated to align with GHS.

  • Hazard Statements: Standardized descriptions of the most significant hazards.

  • Signal Words: Indicate the level of hazard.

  • Precautionary Statements: Guidelines for minimizing hazards and procedures for emergencies.