Go back to Biosafety Manual Table of Contents. A. Risk Assessment Prior to selecting a Biosafety Level, conduct a risk assessment to determine the appropriate work practices and containment requirements. Your assessment should consider properties of the biohazardous material and the procedures to be performed. Use the following points as a general guide and consult the Biosafety Officer for assistance: Material Properties Pathogenicity Agent stability in the environment Infectious Dose Host Range Availability of Effective Therapy Potential outcome of exposure Lab-Acquired Illness Cases Route of Exposure Skin and Mucous Membrane Contact: Common laboratory procedures such as removal of screw caps, vortex mixing, decanting of liquids, pipetting, streaking agar plates and inoculation of animals can create infectious droplets. Droplets can splash into mucous membranes, including the eyes, and fall onto surfaces, creating opportunities for contact with infectious material. Ingestion: Historically, mouth pipetting presented the highest risk for ingestion of infectious material. Today, ingestion is more likely to be associated with touching your mouth with contaminated hands. Storage of food, drinks and other personal items in laboratories can also lead to accidental ingestion of infectious material. Percutaneous Injuries: Accidental inoculation can occur through needlesticks, cuts and scratches from contaminated items and animal bites. Inhalation: Potentially infectious aerosols are formed by a variety of laboratory activities, including centrifugation, heating of loops, changing bedding in cages used to house infected animals. Aerosols are 5 microns or less in diameter and can remain airborne indefinitely. Laboratory Procedures What is the experience and skill level of research staff? Do your manipulations produce droplets or aerosols? Are sharps used? What activities have a high potential for spills and splashes? Who could be exposed and what is their health status? Will you administer the agent to an animal
