Laboratory activity-and equipment-specific factors

When carrying out a risk assessment it is important to list as much as possible, all the potential lab activities that would be carried out and the equipment that would be used when manipulating the hazardous biological agent and / or material. This will help to determine activities and equipment,

*          That have a potential for generating aerosols and droplets

*          That lead to splashes, splatters

*          That need the use of sharps

Looking at reported cases of laboratory acquired infections (LAIs), the main ways in which a hazardous agent can get transmitted include direct exposure to skin, eye or mucous membranes through splashes and splatters, ingestion mainly through contaminated hand to mouth exposure, parenteral exposure through the use of contaminated sharps such as needles and inhalation of infectious aerosols.

It is generally accepted that inhalation of infectious aerosols account for up to 80% of the reported LAIs especially in cases where the only known risk factor for the infected lab personnel has been simply working with the hazardous agent or working in an area where the agent has been handled. Therefore aerosols are a serious hazard and efforts need to be made in assessing the potential for aerosol generation for work processes and equipment used in a project. When used in association with a hazardous biological agent / material, common laboratory activities such as pipetting, mixing, shaking, grinding and equipment such as non-self-contained centrifuges, vortexes and sonicators are capable of generating respirable-sized particles that remain airborne, which can be inhaled by laboratory workers leading to an exposure and a subsequent infection.

When manipulating infectious material and microorganisms, In addition to aerosols, these laboratory procedures and equipment are also capable of generating larger sized droplets containing infectious agents that rapidly settle out of air and get deposited on work surfaces and gloved hands that can lead to ingestion risks through hand to mouth exposure.

Therefore listing the possible work practices and equipment that may be used and determining their risk for generating aerosols, droplets, splashes, splatters and the need for using sharps will greatly help in identifying the possible routes of exposure to hazardous biological agents and material and in coming up with effective controls. Risk assessment is especially needed when undertaking procedures that have previously not been done in the facility or when using a new piece of equipment.

Note: Although the absence of reported LAIs does not necessarily indicate a lack of risk, when published reports of LAIs are available for a specific biological agent it clearly indicates the presence of a risk to laboratory workers from that agent. Information available in these reports can be used in identifying agent and activity specific risks and in coming up with effective controls. Agent Summary Statements given in the 5th edition of the Biosafety in Microbiological and Biomedical Laboratories (BMBL) include references to reports of LAIs for a number of microorganisms while the Pathogen Safety Data Sheets available from the Public Health Agency of Canada also mentions whether LAIs have been reported for a particular biological agent.