The explosion of biotech companies and research into fighting cancer and other diseases, combined with the ever-present threat of biological weapons of mass destruction have propelled concern and discussion of biohazards into prominence. Given the complexities and potential for harm, it is paramount that we promote understanding and sensible approaches to managing biohazards.
Definition, levels, and examples
A biological hazard, biohazard for short, is a biological material that poses potential harm to the health of other living organisms. Most importantly, we are concerned with those that pose threat to humans. However, biohazards may also potentially harm animals, aquatic life, and plants.
Biohazard material could be bacterial, viral, or toxic. The United States Centers for Disease Control and Prevention (CDC) ranks biohazards into four levels, with Level 1 being minimum risk and Level 4 being extreme risk. Here are brief definitions of the levels with examples of biohazards ranked for each:1
- Biohazard Level 1: Well-characterized bacteria and viruses not known to consistently cause disease in healthy adult humans, and of minimal potential hazard to laboratory personnel and the environment. Examples include Escherichia coli, varicella (chicken pox), and feline leukemia virus.
- Biohazard Level 2: Similar to Level 1 agents, but known to cause mild disease in humans or are difficult to contract. Examples include measles, mumps, salmonella, influenza A strains.
- Biohazard Level 3: Indigenous or exotic bacteria and viruses that can cause serious or fatal disease in humans, but for which vaccines or other treatments exist. Examples include anthrax, tuberculosis, yellow fever, and malaria.
- Biohazard Level 4: Biological agents that are likely to cause serious or fatal human disease for which vaccines, preventive, or therapeutic interventions are not available. Examples include Ebola virus, Marburg virus, Lassa fever virus, and other hemorrhagic diseases.
The list of select biological agents includes approximately 40 viruses, bacteria, rickettsia, fungi, and toxins. In the United States, any work with or transfer of these agents is controlled due to their capacity to cause considerable harm to human health. The Federal Select Agent Program developed by the Department of Health and Human Services (HHS) along with the CDC regulates all work with and transfer of select agent material, be it for agriculture, animals or animal products, or public health.
The public health regulations contain five main components2:
- The list of biological “select agents”
- Procedures for registration of facilities that transfer or use these agents. Any organization that transfers or obtains these agents must register with HHS and provide sufficient information that the facility meets all the biosafety level requirements for working with the particular agent or agents
- Process for documenting successful transfer of agents requiring both shipping and receiving parties to complete written record forms
- Audit, quality control, and accountability verification procedures
- Procedures for appropriate disposal of select agents
Other parts of the regulations address exemptions, designation of a facility responsible official, restricted access and security, training, and notification of any theft, loss, or release of material.
Exposure prevention—the primary goal
Efficient and proper management of biohazards begins with preventing exposures. If we are handling or working with biological agents with known human etiology, and especially any agents in biohazard class 2, 3, or 4, we should have the necessary infrastructure in place and a comprehensive written exposure control plan in effect.
The exposure control plan (ECP) is written to address the unique conditions of the current operations, research, facility design, and personnel actions necessary to carry out the facility’s mission. One exceptional reference for developing your ECP is the CDC’s Biosafety in Microbiological and Biomedical Laboratories3 (BMBL), which contains ample information on biological risk assessment. A good companion to the BMBL is OSHA’s model ECP contained in Appendix D of 29 CFR 1910.1030.4 A good ECP should address the following key elements:
- Administration, responsibilities, and accountability: Provides a clear organization of personnel and assigns responsibilities for implementation and support, and identifies positions and/or departments responsible for reviewing and updating the ECP, maintaining and providing necessary personal protective equipment, engineering controls, and other infrastructure and equipment
- Determination of employee exposure: Identifies all employees that have potential occupational exposure and conducts job hazard analyses and exposure assessments
- Exposure control methods: Details specific procedures for safe work including engineering controls, PPE, universal precautions, signage, access, and security
- Health and medical monitoring: Protects against laboratory-acquired illness by documenting and certifying the necessary immunizations and vaccinations are attained
- Emergency procedures: Describes procedures for reporting and investigating any accident, exposure incident, spill, or release that injures laboratory staff or contaminates the environment
- Employee training: Ensures that everyone working in the containment facility has been trained on and understands the ECP. Informs employees about each infectious agent present, the associated risks, and the signs and symptoms of infection or disease
- Reporting and recordkeeping: Ensures procedures for identifying, reporting, and correcting exposures, incidents, near misses, or violations of protocol are recorded, investigated, and corrected
A final major element of managing biohazards is the task of handling the wastes properly. Questions abound due to biohazardous waste versus medical waste and the inevitable mixing of the two. You need to know in which category to place the waste and the proper protocols for treatment and disposal.
If a waste meets any of the criteria below, it is usually considered a biohazardous waste:
- Laboratory waste, including but not limited to:
- Human or animal specimen cultures from medical or pathology labs
- Research laboratory cultures and stocks of infectious agents
- Waste from the production of bacteria, viruses, spores
- Discarded live and attenuated vaccines used in healthcare or research
- Discarded animal vaccines
- Culture dishes and devices used to transfer, inoculate, or mix cultures
- Human surgery or autopsy specimens or tissues suspected of being contaminated with infectious agents
- Animal parts, tissues, fluids, or carcasses suspected of being contaminated with infectious agents
- Waste that contains fluid blood, blood products
- Containers or equipment containing blood
- Blood from animals known to be infected with diseases highly communicable to humans
Biohazardous waste disposal
If you are disposing of any CDC-listed select agent waste, be sure to follow all regulations of the Federal Select Agent Program. In addition, be sure to check with all local agencies (e.g. sanitary landfill or sewer departments) for approval prior to disposal.
In general, solid biohazardous waste should be sterilized or otherwise inactivated and rendered noninfectious prior to disposal as normal sanitary waste. Inactivation is achieved by autoclaving or by vapor sterilization with ethylene oxide, formaldehyde, glutaraldehyde, hydrogen peroxide, or other approved methods. Liquid biohazardous waste must be inactivated using appropriate chemical disinfection prior to discharge to the sanitary sewer. Animal carcasses and other large solids should be disposed through an approved vendor or other special means such as incineration or chemical decomposition.
Medical wastes and their disposal
Medical wastes are generally defined as biohazardous waste (see above) or sharps and are generated or produced by the following activities:
- Diagnosis, treatment, or immunization of humans or animals
- Research associated with the above
- The production or testing of medicinal serums, vaccines, antigens, or antitoxins made from living organisms
Generally, all medical wastes are disposed through approved, contracted specialty vendors. Any other means of disposal must be authorized and approved by all federal, state, and local agencies.
1. Biohazard Levels, Bayot, Marion L. and King, Kevin C., National Center for Biotechnology Information, US National Library of Medicine. Bethesda, MD. 2019
2. Select Agents and Toxins, US Department of Health and Human Services, Title 42, Part 73. Washington, D.C. December 2012
3. Biosafety in Microbiological and Biomedical Laboratories, 5th edition, Center for Disease Control and National Institute of Health, December 2009
4. Model Exposure Control Plan, OSHA Bloodborne pathogen standard, 29CFR1910.1030, Appendix D. Occupational Safety and Health Administration. Washington, D.C. April 2012