The document summarizes personal breathing zone exposure monitoring conducted for isoflurane, an anesthetic agent, at a research facility in India. Air sampling found that exposures for surgeons, investigators, and support staff were all less than 10% of the UK workplace exposure limit when standard operating procedures and engineering controls like local exhaust ventilation and activated charcoal filters were followed. Recommendations included improving the local exhaust ventilation system and providing backup power in case of failures. The monitoring demonstrated that exposures were well below limits when proper precautions were taken.

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Personal breathing zone exposure
monitoring for an anesthetic agent at a
research and development facility in India
Ankit Sharma, CIH, LFOH
International Safety Systems, Inc.

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Agenda
• Background
• Anesthetic agent monitored
• Methods used
• Monitored locations / exposure groups
• Processes
• Results
• Recommendations
• Lessons Learnt

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Background
Anesthetic agents are administered to animals during surgeries
in research and development procedures.
Anesthesia:
• analgesia (pain relief)
• amnesia (loss of memory)
• immobilization.
The drugs used to achieve anesthesia usually have varying
effects in each of these areas.

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Background (contd.)
Inhalation Anesthesia
Advantages:
• Superior to most injectable forms in safety and efficacy.
• Easy to adjust the anesthetic depth.
• Less potential for drug-induced toxicity.
Disadvantages:
• The complexity and cost of the equipment.
• Potential hazards to personnel.
• Volatile liquids, should not be stored in animal rooms because the vapors
are either flammable or toxic to inhale over extended periods of time.
Source: http://www.ahc.umn.edu/rar/anesthesia.html

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Background (contd.)
Comparison of inhalant agents:
Important terminology:
MAC:
• % concentration of the drug needed to anesthetize 50% of animals.
• Varies somewhat by species and by individual.
• 1.2X MAC is an approximate vaporizer setting for maintenance of
anesthesia. Induction generally requires 2-3X MAC.
Response:
• How rapidly concentrations in the blood change when the lung alveolar
concentration is changed.
• Slow anesthetics have slow induction and recovery times.
Source: http://www.ahc.umn.edu/rar/anesthesia.html

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Drug MAC Response Toxicity Comments
Ether 3.2 Slow Hepatoxicity Pre-medication with an
anticholinergic may be
necessary to reduce
excessive respiratory
secretions. Induction and
recovery can be rough.
Methoxyflurane 0.2 Slow Nephrotoxicity
(potentiated
by
tetracyclines)
This drug is not currently
being manufactured. For a
replacement, consider ether
or diluted isoflurane.
Isoflurane 1.5 Fast None Respiratory depression,
cardiovascular depression
Enflurane 2.5 Fast None Minimal respiratory
depression, cardiovascular
depression
Halothane 0.9 Moderate Nephrotoxic,
mutagenic
Cardiopulmonary depression,
risk of hyperthermia

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Anesthetic agent monitored
Isoflurane:
• HSE UK established Workplace Exposure Limit(WEL)-
TWA: 50 ppm (used as guideline value)
• Halogenated hydrocarbon – mild ether-like odor
• Acute exposure: nausea, vomiting, headache, dizziness
• Chronic exposure: Tachycardia, respiratory depression,
reproductive effects

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Methods
Sampling methods:
• Monitoring device – active air sampling pumps for personal breathing
zone monitoring
• Media - Anasorb 747
• Flowrate - 0.05 lpm
• Duration - ~ 8 hours
Analytical methods:
• OSHA 103; Gas Chromatography/Flame Ionization Detector

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Monitored Locations / Exposure Groups
Full shift TWA personal breathing zone air samples were collected during
surgery (PCO surgery lab) and investigation/ immunization (immunology
laboratory) for support staff.
Task based samples collected for surgeons / investigators and normalized into
TWA exposures.
Surgery:
• Surgeons
• Support staff
Investigation / Immunization:
• Investigators / Surgeons
• Support staff

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Surgery - Process
Different surgeons performed different surgeries, common support
staff assisting different surgeons throughout the shift.
• Rats kept in induction chamber prior to surgery.
• Induction chamber supplied with < 5 % isoflurane in oxygen at
approximate flowrate of 3 liters per minute (lpm) through a manifold with
pressure regulated supply system.
• After desired sedation / induction, rats were lifted from and placed on
surgery bench.
Scavenging: Spot extractor available over the induction chamber.
Waste anesthetic gases passed through an activated charcoal filter.

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Surgery was performed by surgeon.
• Pre-sedated rat/mice was supplied with continuous oxygen
supply (with less than 5 % Isoflurane) through a ‘nose hose’
during surgery.
Engineering controls during surgery:
• Prototype LEV
Work
Surface
Engineering controls validated by face velocity
measurements.
Nose
Hose
Rat/mice
placed
between
two
extraction
arms

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Investigation - Process
• Similar process as compared to surgery. Major difference is that testing /
investigation being performed on rats / mice were slightly different than
surgery.
Differences in engineering controls between Investigation and Surgery
Investigation Surgery
Induction chamber was provided
with a prototyped Local Exhaust
Ventilation
Induction chamber was provided
with spot extractors.
The waste gas discharge hose was
terminated at the inlet of
prototype LEV.
The waste gas discharge hose was
terminated through activated
charcoal filter.

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Results
Process Exposure Group* Number of samples
collected**
Results
Surgery Surgeons 5 < 10 % of guidance
value
Support Staff 3 < 10 % guidance
value
Investigation Investigators 2 < 10 % of guidance
value
Support Staff 3 < 10 % of guidance
value
** - The number of samples collected varied due to limited availability of activities for
investigation process.
*- Full shift samples were collected for support staff , as they were potentially exposed to
Isoflurane throughout the shift. Surgeons / Investigators were rotated between surgeries and
hence task based samples were collected , which were normalized to TWA after ensuring that
there was no potential for exposure to isoflurane before or after activity.

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Discretionary Recommendations:
• Review feasibility of clamping the flexible waste anesthetic gas hose near
the suction arm of the prototyped LEV (in case site decides to stop use of
activated charcoal canisters for discharging waste gases).
• Consider providing emergency power back-up for the prototype LEVs and
spot extractors used for performing surgery.
(As observed in case of a power failure, the mixture (isoflurane and oxygen)
supply had remained operational through the power cut to provide life
support to rat, thus releasing isoflurane in breathing zone air of surgeon in
temporary absence of prototype LEV)

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Lessons Learnt
• Engineering controls provided by the site were
effective in reducing employee exposures below the
HSE UK established WEL-TWA considered as guideline
value.
• Considering variation in number of surgeries
performed by surgeons, the employee exposures are
still expected to be considerably below the exposure
limit during higher work-load for surgeons /
investigators than observed during the assessment.

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Thank You
Any questions?
Ankit Sharma, CIH, LFOH
ankit.sharma@issehs.com