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SECTION VI
Risk Assessment
The assessment of risks associated with laboratory activities involving the use of infectious microorganisms is ultimately a subjective process. The risks associated with the agent, as well as with the activity to be conducted, must be considered in the assessment. The characteristics of infectious agents and the primary laboratory hazards of working with the agents are described generically for agents in Biosafety Levels 1-4 and specifically for individual agents or groups of agents in Section VII of this publication.
Hepatitis B (HBv) is an appropriate model for illustrating the risk assessment process. HBv is among the most ubiquitous of human pathogens and most prevalent of laboratory-associated infections. The agent has been demonstrated in a variety of body secretions and excretions. Blood, saliva, and semen have been shown to contain the virus. Natural transmission is associated with parenteral inoculation or with contamination of broken skin or mucous membranes with infectious body fluids. There is no evidence of airborne or interpersonal spread through casual contact. Prophylactic measures include the use of a licensed vaccine in high-risk groups and the use of hepatitis B immune globulin following overt exposures.
The primary risks of HBv infection for laboratory personnel are accidental parenteral inoculation, exposure of broken skin or the mucous membranes of eyes, nose, or mouth. These risks are typical of those described for Biosafety Level 2 agents, and are addressed by using the recommended standard and special microbiological practices to minimize or eliminate these overt exposures.
The routes of infection with hepatitis C virus (non A-non B) and human immunodeficiency virus are similar for laboratory personnel. The prudent practices recommended for HBv are applicable to these two pathogens, as well as to the routine laboratory manipulation of clinical materials of domestic origin.
The described risk assessment process is also applicable to laboratory operations other than those involving the use of primary agents of human disease. Microbiological studies of animal host-specific pathogens, soil, water, food, feeds, and other natural or manufactured materials, by comparison, pose substantially lower risks for the laboratory worker. Microbiologists and other scientists working with such materials may, nevertheless, find the practices, containment equipment, and facility recommendations described in this publication of value in developing operational standards to meet their own assessed needs.
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Office of Health and Safety, Centers for Disease Control and Prevention, 1600 Clifton Road N.E., Mail Stop F05 Atlanta, Georgia 30333, USA Last Modified: 1/2/97 |
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