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Welcome to our Bioaerosols, Laboratory Acquired Infections and Medical Surveillance tutorial. This tutorial is intended to explain the hazards posed by aerosol exposure, infections from exposure to laboratory hazards and the medical surveillance program.

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What are aerosols?

Aerosols are defined as colloidal suspensions of liquid or solid particles dispersed in a gas, usually air.

What is a bioaerosol? A collection of airborne biological particles. Generally a bioaerosol is generated as poly-dispersed droplets of particles of different sizes ranging from 0.3 to 30 micrometers in diameter. Laboratory studies, through air sampling determinations, of potential sources of infection, have focused on hazards associated with bio-aerosols produced from microbiological techniques. Aerosols present two separate means of potential personnel exposure: through breathable infectious airborne particles, and by the disposition of heavy droplets onto surfaces, equipment and personnel. The figure shows an example of aerosol formation through pipetting.

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Inhalation of aerosols.There exist different sized aerosols and consequently, different routes of possible infection. Inhalation, ingestion and dermal contact are routes of human exposure for airborne micro-organisms. Inhalation is the main route giving adverse health effects. The average human inhales approximately 10 cubic meters of air per day. Large airborne particles can become lodged in the upper respiratory tract. Generally, particles less than 6 micrometers in diameter, are transported to the lung, but the greatest retention occurs in the alveoli, retaining particles of 1 to 2 micrometers in diameter. After penetration, infection also depends on the nature and concentration of the infectious agents present in the aerosols.

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Classification of aerosols.

Once aerosols are generated, settling velocity can vary greatly depending on the particle type. The greater the settling velocity, the lesser the risk of exposure to the operator. The table shows the size classification of aerosols.

The larger droplets, greater than 100 micrometers in diameter settle quickly, and contaminate the surfaces upon which settle. The smaller droplets do not settle but evaporate very rapidly. For example : droplets with a diameter of 100 micrometers evaporated in 1.7 seconds, and those with a diameter of 50 micrometer in 0.4 seconds.

The micro-organisms in droplets remain in a dried state as "droplet nuclei", also referred to as infectious airborne particles. Such particles are moved around rooms and buildings by air currents generated by ventilation systems and the movement of people. The smaller the droplet nuclei, the greater the potential for travelling long distances.

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Common laboratory techniques that produce aerosols.

There are many common laboratory micro-biological techniques which produce aerosols consisting of various sizes of particles.

Laboratory activities releasing aerosol particles include the following:-Opening containers;-Pipetting;-Mixing test tubes;-Opening lyophilized cultures;-Centrifugation;-Pouring;-Fixed-volume automatic pipettors;-High-speed homogenizers;-Shaking machines;-Cell sorting.

Of note, cell sorters are equipped with a nozzle to form a jet of micro-droplets. Instrument failures such as clogged sort nozzle or air in the fluidic system can drastically increase aerosol formation. A droplet containment module should be

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installed to reduce the risk of exposure to generated droplets and aerosols.

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Procedures to minimize aerosols.

The Public Health Agency of Canada has produced a poster outlining ways to minimize aerosol hazards as a part of good microbiological practices. This poster can be found on the McMaster Biosafety Website. This poster should be visible within your laboratory. The Research Compliance Auditor distributes laminated, letter-sized, colour copies during your scheduled biosafety audit. You are also encouraged to print this and keep it at your bench.

Please see the PDF with the slides and notes for website addresses.

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PHAC Procedures to Minimize Aerosols: https://biosafety.mcmaster.ca/documents/doc047_PHAC_procedures_to_minimize_aerosol_hazards.pdf

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Opening tubes.

It is recommended to manipulate infectious materials in a biological safety cabinet.

When opening tubes, unscrew the cap slightly and wait a few seconds before opening it.

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Inoculating loop.

When working with bacteria and fungi is preferable to use disposable loops.

Use of micro-incinerators is preferable over Bunsen burners, especially inside a biological safety cabinet. If using a Bunsen burner, with the loop pointing down flame the base, moving towards the tip. This will kill microbes before aerosolizing them.

When inoculating or streaking, you must allow the inoculating loop to cool before any procedures.

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Syringes and needles.

Always withdraw needles from bottles using disinfectant-soaked absorbent pads wrapped around the bottle cap. Disinfect the bottle cap before and after withdrawal.

It is preferable to use syringes with luer-locks. Slip-tip or tapered tip syringes are not recommended.

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Pipetting.

It is preferable to use ‘to deliver’ pipetmen, calibrated to retain the last drop.

Use pipette tips with aerosol plugs or ‘plugged tips’.

Discharge liquids close to the fluid level and let the contents run down the wall of the container.

Never forcefully expel infectious materials from the pipette.

Never lay the pipette on its side when liquid is in the tip. This could cause the liquid to enter the shaft and piston area of the pipette.

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Centrifugation.

Always centrifuge infectious materials in closed containers, seated in safety cups or safety rotors.

After spinning, bring the safety cups or safety rotor to the biological safety cabinet and open inside the BSC.

Always maintain the centrifuge to ensure that it is clean, and that the gaskets and O-rings are not compromised. Every centrifuge should be labeled with contact information of the person responsible for its upkeep. If information is not present, please report this to your Supervisor to ensure it is labelled. This is especially true for equipment in common rooms.

Wait 5 minutes before opening the centrifuge after each run to allow any aerosols to settle within the tubes. In the event of a spill refer to the biological spills training module and your laboratory’s spill protocols.

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Tube breakage.Avoid the use of glassware where possible.Use plastic tubes, flasks and bottles.Use screw-capped tubes and bottles rather than plugs or snap caps.

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Mixing and homogenizing.

Always ensure the lab blender has a sample tubes or a sample chamber, with a gasket lid, and leak-proof bearings to prevent contamination of the inner parts of the equipment. Always wait a few seconds before opening a lid after mixing. Use a vortex, instead of inverting the cultures.

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Pouring Infectious Materials.

When pouring materials, perform your work over plastic-backed absorbent material. Wipe the rim of the tube with disinfectant-soaked absorbent paper to remove potential contamination on the outside of the tube.

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In summary.

Aerosols are produced during routine laboratory procedures. Aerosols are an inhalation hazard. Aerosols are also an ingestion and contact hazard when they have settled on surfaces. Take care during routine lab procedures to prevent the formation of aerosols.

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Laboratory acquired infections are an occupational hazard. They result from exposure to infectious agents whether they are intentionally cultured agents or exist in the workplace environment. Exposure to infectious agents can occur by contact with contaminated items such as waste materials and by products of work processes. Exposure to infectious agents can also occur by contact with diagnostic or research samples, whether during direct handling such as in the case of a research technician or during indirect handling such as in the case housekeeping during waste pickup and removal.

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Laboratory acquired infections are always associated with an exposure, however this exposure may be a part of something very obvious such as an incident or accident or you may be unaware of the exposure. It is for these reasons why a local risk assessment of any procedure be scrutinized for risks of potential release and exposure to biohazards.

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A local risk assessment, or LRA, is required for all procedures involving hazards. The first step in a local risk assessment is to create a procedure for the steps to be taken and the equipment to be used. For each step, examine the procedure for any risks which may result in an accident or exposure or spill. Once identified, modify the procedure to protect against those risks. The entire document is then written up in a standard operating procedure. This standard operating procedure is to be reviewed regularly and updated where necessary.

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Exposure and Infectious Dose.

An infection cannot occur without an exposure, however being exposed to a biohazard does not necessarily mean that an infection will take place. This may be because the amount of biohazard was not high enough, or the body clears the biohazard very effectively or the route of exposure was not conducive to infection.

The amount of biohazard required to establish an infection is called the ‘infectious dose’. The infectious dose depends on so many different factors, it cannot be relied upon. In fact the American Biological Safety Association was asked to determine the permissible exposure levels for a number of biohazards. The white paper linked in the upper right hand corner describes the result of this request: too many factors involved to accurately determine infectious dose and any efforts to do so would not benefit the occupational safety of workers.

In line with this, all persons must assume these two facts (1) all research materials are in concentrations well above any infectious dose and (2) every exposure will cause infection. We make these two assumptions, because we do not have the information required or the resources required to determine otherwise. Therefore, risk assessments should be conducted and standard operating procedures should be

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designed accordingly.

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OSHA Infectious Dose White Paper: http://www.absa.org/pdf/OSHA_white_paper.pdf

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Exposure Routes.

For every work practice, there is a risk of incident leading to an exposure. Exposures can be through spills and splashes to skin and mucous membranes such as mouth, eyes and nose. Exposures can be through ingestion such as by a splash to the mouth or touching contaminated items and then putting your fingers in your mouth or even by putting contaminated items in your mouth such as pens and pencils. Exposure can also take place in the form of an inoculation which can occur by a needle stick injury, a cut injury or an animal bite injury. The most common route of exposure is through inhalation and is by far the most unnoticed or underreported. Inhalation of biohazards can occur by inhaling aerosols generated by poor laboratory procedures or during a spill of biohazardous liquids. Inhalation of contaminated dusts or mists is also possible. Similar to spills and splashes, exposure to mucous membranes such as mouth, nose and eyes can occur by touching these membranes with your contaminated hands. Exposure can also occur by direct skin contamination if the biohazard can penetrate the skin barrier or, more likely, is suspended in a media that increases penetration across the skin. It is important to be aware of all of these exposure routes when performing local risk assessments, designing standard operating procedures and carrying out work tasks.

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Prevention of laboratory acquired infections starts with the use of good microbiological practices. All practices should also minimize the generation of aerosols. There are two posters available for your laboratory. Links to these posters are found in the PDF containing the slides and notes. Although laminated copies are distributed by the Research Safety Compliance Auditor during your lab audits, it is recommended that you print each of these posters and keep them in your notebook as a reminder.

Always keep sample containers closed when not pipetting or pouring, to decrease the risk of spill if bumped or knocked over.

Practice safe sharps handling, or better yet, minimize the use of sharps and substitute safety-engineered sharps whenever possible.

Never practice oral pipetting.

Wear gloves appropriate for the work that you are performing. See RMM321 for the safety policy on hand protection which includes help for the selection of appropriate types of gloves.

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Wash your hands frequently. This is the single most important way to prevent spread of infection.

Segregate working areas from desk areas. Please refer to the Lab Layout SOP and Desk Area signs posted on the biosafety SOPS website. A link to the websites can be found in the PDF containing the slides and notes.

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PHAC Good Microbiological Practices Poster: https://biosafety.mcmaster.ca/documents/doc012_biosafety_in_the_laboratory_PHAC.pdfPHAC Procedures to Minimize Generation of Aerosols Poster: https://biosafety.mcmaster.ca/documents/doc047_PHAC_procedures_to_minimize_aerosol_hazards.pdfRMM321 Hand Protection Program: http://www.workingatmcmaster.ca/med/document/RMM-321-Hand-Protection-Program-1-36.pdfBiosafety SOP Website: https://biosafety.mcmaster.ca/biosafety_SOPs.htm

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Reporting exposures and laboratory acquired infections is mandatory for all persons. Exposure reporting is completed through the incident reporting system described in RMM1000. Exposure and incident reporting is beneficial to everyone for the following reasons:

• It identifies gaps in training, which allows the university to improve their training materials.

• It identifies faults in equipment, which allows the supervisor to ensure repairs are made or to review the suitability of the equipment for the tasks.

• It identifies faults in safety barriers such as perimeter containment, directional airflows, personal protective equipment and operational procedures.

• Overall it improves operational and engineering controls that are geared to protect workers.

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RMM1000 Incident Reporting: http://www.workingatmcmaster.ca/med/document/RMM-1000-Reporting-and-Investigating-Injury-Incident-Occupational-Disease-Program-1-36.pdfIncident Reporting Form: http://www.workingatmcmaster.ca/med/document/injury-

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incident-report-fillable-1-36.pdf

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In summary, laboratory acquired infections are an occupational risk. Exposures may be obvious, or you may be unaware of the exposures. There are multiple routes of exposure however assume that all routes and all doses result in infection. Prevention of laboratory acquired infections occurs through thorough local risk assessments, well written standard operating procedures and use of good microbiological practices. Reporting of laboratory acquired infections will result in changes to the program which will benefit everyone.

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The medical surveillance program was put in place to ensure that all workers were aware of the following:

• The risks posed by use of the materials• Available vaccinations against the materials• The vaccination and titering processes• Emergency procedures and location of closest emergency or urgent care• The requirements for self monitoring, especially after exposure incidents• The requirements for reporting symptoms or illness to the Supervisor

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All Supervisors shall:

• Facilitate the lab-wide dissemination of information related to this program.• Ensure all individuals under their supervision are aware of and execute their

responsibilities under this program.• Ensure all biological inventory and immunization sections on the BUP are up to

date.• Ensure all biological inventory items, that are pathogenic to humans, have

associated safety documentation equivalent to a PSDS. Ensure all individuals under their supervision who are conducting controlled activities with any inventory items approved for use for that Supervisor, are aware of the risks and symptoms associated with exposure to such inventory items.

• Prohibit any individual from conducting controlled activities with any inventory items approved for use for that Supervisor unless they are aware of the risks to health and wellbeing and of the symptoms associated with exposure to inventory items in use.

• Complete a local emergency response plan which lists the closest urgent care centre or emergency room, their street address and their operating hours.

• Identify individuals working with inventory items for which immunizations are available and ensure those individuals are aware of and understand the immunizations and required titers for immunity that are recommended for such work.

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• Ensure all individuals are monitoring their health status on an ongoing basis. Use the form in Appendix A to annually affirm that self-monitoring is carried out by each individual as documentation of due diligence.

• Ensure accommodation is provided to individuals as recommended by EHS or SAS.

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All Individuals shall:

• Carry out their work as directed by their Supervisor.• Consider recommendations given by their Supervisor for immunizations.• Complete the form in Appendix A and update on an annual basis to indicate they

are monitoring their health status on an ongoing basis.• Follow post exposure procedures as described in this RMM upon exposure to an

infectious material, organism or toxin.• Seek consultation with EHS (employees) or SAS (students) on the occasion:

• They have a physical limitation such that they cannot adhere to safe practices described in work-related standard operating procedures.

• They have a new or pre-existing medical condition that would increase the risk of disease or severity of disease if exposed.

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Post Exposure Procedures

Following exposure: • Follow first aid recommendations found in the PSDS for the organism if available.• Follow first aid recommendations found in RMM407 for all other exposures.• Inform their supervisor of the incident.• Within 1-2 hours, seek immediate medical attention, bringing any information on

the biological inventory item to which the authorized person was exposed.• Complete a Injury/Incident Form and arrange for it to be sent to the FHS Safety

Office or EOHSS as soon as possible within 24 hours of the incident as per RMM1000 – Reporting & Investigating Injury/Incident/Occupational Disease Program.

• Adhere to the course of treatment prescribed by the initial health care provider, including PEP and follow up appointments.

• Obtain follow-up care and/or support as appropriate (e.g. from own family physician or McMaster Student Wellness Centre).

• Arrange with supervisor for any accommodations or absences that may arise from the incident in accordance with program or university policies.

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Summary

The Medical Surveillance Program, RMM603 includes responsibilities for both the Supervisor and the Worker.

The program provides awareness of the hazardous materials in use and the protective measures to take in order to work safely.

There should be a location-specific emergency response plan which includes important emergency information such as medical consultation.

The program requires that all incidents and exposures be reported and that accommodation should be provided where appropriate.

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Thank you for your participation.

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