5.5 Biological Hazards, Bloodborne Pathogens & Infection Control

Biological Hazards and Bloodborne Pathogens

Biological hazards (biohazards) represent a unique class of occupational risks. Unlike chemicals which are inert, biohazards are living organisms—or products of living organisms—that can cause infection, allergic reactions, or toxicity in humans. Common biohazards include bacteria, viruses, fungi, molds, and parasites.

Workers in healthcare, laboratories, agriculture, wastewater treatment, and emergency response face the highest risks of biological exposure.

The OSHA Bloodborne Pathogens (BBP) Standard

One of the most critical regulatory frameworks regarding biological hazards is the OSHA Bloodborne Pathogens Standard (29 CFR 1910.1030). This standard is designed to protect employees from occupational exposure to blood and Other Potentially Infectious Materials (OPIM).

• Bloodborne Pathogens: Pathogenic microorganisms present in human blood that can cause disease. The most prominent concerns in occupational settings are Hepatitis B Virus (HBV), Hepatitis C Virus (HCV), and Human Immunodeficiency Virus (HIV).
• OPIM: Includes semen, vaginal secretions, cerebrospinal fluid, synovial fluid, pleural fluid, any body fluid visibly contaminated with blood, and all body fluids in situations where it is difficult or impossible to differentiate between body fluids.

Universal Precautions

The cornerstone of the BBP standard is the concept of Universal Precautions. Under this approach, all human blood and OPIM are treated as if they are known to be infectious for HIV, HBV, and other bloodborne pathogens. Regardless of a patient's or victim's perceived health status, workers must use the same rigorous precautions, PPE, and handling procedures.

The Exposure Control Plan (ECP)

Employers with workers who have reasonably anticipated exposure to blood or OPIM must establish a written Exposure Control Plan. This plan is the blueprint for compliance and must include:

1. Exposure Determination: A list of all job classifications, tasks, and procedures in which occupational exposure occurs, without regard to the use of PPE.
2. Methods of Compliance: Details on how Universal Precautions, engineering controls, work practice controls, and PPE will be implemented.
3. Hepatitis B Vaccination: Procedures for offering the vaccine.
4. Post-Exposure Evaluation and Follow-up: Procedures for evaluating the circumstances of an exposure incident (e.g., a needlestick) and providing medical follow-up.
5. Annual Review: The ECP must be updated at least annually to reflect new tasks, procedures, and the consideration of safer medical devices (like selfsheathing needles).

Engineering and Work Practice Controls

OSHA prioritizes engineering and work practice controls to eliminate or minimize exposure before relying on PPE.

• Engineering Controls: Isolate or remove the hazard from the workplace. Examples include sharps disposal containers, self-sheathing needles, and needleless IV systems. Sharps containers must be puncture-resistant, leak-proof, color-coded red, and labeled with the biohazard symbol.
• Work Practice Controls: Alter the manner in which a task is performed. Examples include prohibiting two-handed needle recapping (mandating a one-handed scoop technique instead), restricting eating or drinking in areas with potential exposure, and mandatory handwashing immediately after removing gloves.

Hepatitis B Vaccination

Employers must make the Hepatitis B vaccination series available to all employees who have occupational exposure.

• The vaccine must be offered free of charge.
• It must be offered within 10 working days of initial assignment to a job with exposure.
• If an employee declines the vaccination, they must sign a mandatory declination form, but they can opt to receive the vaccine at a later date if they remain at risk.

Biosafety Levels (BSLs)

In laboratory environments where biological agents are intentionally handled or cultured, the CDC and NIH have established four Biosafety Levels. These levels prescribe strict work practices, safety equipment, and facility design criteria based on the risk of the agents.

• BSL-1: Suitable for work involving well-characterized agents not known to consistently cause disease in healthy adults (e.g., non-pathogenic E. coli). Requires standard microbiological practices; no special containment equipment is required.
• BSL-2: Suitable for work involving agents that pose moderate hazards (e.g., Staphylococcus aureus, Salmonella, HIV). Access is restricted, and biological safety cabinets (BSCs) are used for procedures that might cause splashes or aerosols.
• BSL-3: Applicable to facilities working with indigenous or exotic agents that may cause serious or potentially lethal disease through the inhalation route (e.g., Mycobacterium tuberculosis, SARS-CoV-2). Requires directional inward airflow (negative pressure), HEPA filtration of exhaust air, and all work is done within BSCs.
• BSL-4: The highest level of containment, used for dangerous and exotic agents that pose a high individual risk of aerosol-transmitted laboratory infections and life-threatening disease for which there are no vaccines or treatments (e.g., Ebola virus, Marburg virus). Requires full-body, air-supplied positive pressure suits, dedicated air supply, and highly specialized facility engineering.

Understanding these frameworks allows technicians to properly risk-assess biological hazards, whether responding to a first-aid incident in a factory or inspecting a clinical laboratory.