Standard Operating Procedure for Isoflurane


Standard Operating Procedure for Isoflurane

EHS SOP #: 003

Version No.: 1.0

Supercedes: N/A

Isoflurane Formula


Isoflurane is a halogenated anesthetic gas commonly used in University animal research facilities and individual laboratories. This document establishes procedures for the safe handling and use of 1-chloro-2,2,2-trifluoroethyl difluoromethyl ether (CAS# 26675-46-7), commonly known as isoflurane or Forane®.

Health Effects

Isoflurane is a halogenated hydrocarbon that is a clear, colorless volatile liquid at standard temperature and pressure with a mild ether-like odor. It is known to cause serious eye irritation and human exposure to waste anesthetic gases has been associated with reproductive effects.

Signs of acute exposure

Nausea, vomiting, nose/throat/respiratory irritation, headache, dizziness, drowsiness, and skin irritation.

Signs of chronic exposure

Hypotension (low blood pressure), tachycardia (increased heart rate), respiratory depression, and elevated blood glucose.

Regulatory Limits

The Federal Occupational Safety and Health Administration (OSHA) do not have a Permissible Exposure Limit (PEL) for isoflurane. The National Institute of Occupational Safety and Health (NIOSH) have established a Recommended Exposure Limit (REL) of 2 ppm as a ceiling limit over a 1-hour time period for all halogenated anesthetic agents (1977; Publication 77-140). Isoflurane was developed later and was not included in this standard setting process so its applicability is questionable. However, based on potential risks it is recommended that no worker should be exposed to greater than 2 ppm of any halogenated anesthetic agent including isoflurane.

Air monitoring

  • Area monitoring can be requested to assess potential exposures in the general laboratory work area. The monitoring is performed using a direct read instrument to give concentrations in room during surgeries or other procedures.
  • Personal monitoring can be requested to determine potential exposures for individual employees who work with isoflurane. The monitoring is performed using a passive dosimeter that the employee wears in their breathing zone to quantify potential exposure.
  • Air monitoring can be requested by contacting Environment, Health & Safety (EHS) at 919-962-5507.


Based on the risk associated with the use of waste anesthetic gases the safety procedures outlined below are required by all research staff when working with isoflurane.

Administrative Controls

  • Institutional Animal Care and Use Committee (IACUC) protocols that include isoflurane should reference this SOP to verify that the standard operating procedures are being followed.
  • Anyone who handles isoflurane is required to review this SOP and the attached Safety Data Sheet (SDS) prior to work.

Engineering Controls

  • Isoflurane must be used in a well-ventilated room from which there is no recirculation of exhaust air.
  • Active scavenging is optimal for scavenging waste gas and can include any of the following:
    • Delivery of anesthetic inside a certified chemical fume hood or ducted biological safety cabinet (BSC). Use of the “drop method” should always be done using this method unless air monitoring has verified exposure levels below REL.
    • Connection of vaporizer and/or induction box exhaust hose into a certified chemical fume hood or ducted BSC.
    • Connection of vaporizer and/or induction box exhaust hose to house vacuum.
  • Passive scavenging can be used safely if specific procedures are followed. Passive scavenging relies on the positive pressure from the anesthetic gas delivery system and/or the exhalation effort of the animal to drive contaminated exhaled air through a specially designed activated carbon charcoal filter (such as F/AIR). The charcoal canister will adsorb and remove the waste gas before being discharged back into the room. Charcoal canisters have a finite effective life span, which can be monitored by weight.
    • The weight of each new canister should be recorded before its first use.
    • Before each subsequent use, the weight should be checked and recorded. If the total increase is close to 50 g, it should be replaced, or monitored closely during use (weigh between animals).
    • To function appropriately, the carbon canister must be at a level below that of the vaporizer, to assist passive scavenging.
    • To function appropriately, the carbon canister must be in an upright/vertical position.
    • To function appropriately with adequate air flow, the holes on the bottom of the carbon canister must not be blocked.

Personal Protective Equipment (PPE)

  • Nitrile gloves, a lab coat, and safety glasses.
  • When in rodent barrier facilities, PPE use must be consistent with the facility policy.

Waste Disposal

  • Unused solutions of isoflurane will be disposed of as a hazardous material through EHS.

Accidents or Injuries

Spill Procedures

  • Do not attempt to clean-up if you feel unsure of your ability to do so or if you perceive the risk to be greater than normal laboratory operations.
  • Small volumes of isoflurane evaporate readily at normal room temperatures, and may dissipate before any attempts to clean up or collect the liquid are initiated. If a small spill occurs rapidly absorb any liquid with absorbent pads or paper towels and place in chemical fume hood for safe evaporation.
  • If a large spill occurs notify others in the area and evacuate room immediately. Contact EHS (919-962-5507) during working hours and 911 if after hours.

Contact Information

Policy Contact

Environment, Health & Safety
1120 Estes Drive
Campus Box #1650
Chapel Hill, NC 27599-1650
Phone: 919-962-5507

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Article ID: 132073
Thu 4/8/21 9:23 PM
Tue 10/18/22 10:56 AM
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