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Safe Use of Isoflurane in Animal Research


Close up image of isoflurane machine

Isoflurane is a halogenated anesthetic gas commonly used to anesthetize research animals. Although safer than other types of anesthetic gases such as enflurane and ether, care must be taken to minimize individual exposure to isoflurane.

Waste anesthetic gas (WAG) is the small amount of anesthetic that may leak from the breathing circuit and enter the environment, presenting an exposure risk to the operator.

The National Institute for Occupational Safety and Health has established a recommended exposure limit (REL) of 2.0 parts per million (ppm) as a ceiling limit (average over a 60-minute period) for halogenated anesthetic gases, including isoflurane.

Potential symptoms of exposure to elevated levels of isoflurane include:

  • Irritation of the eyes, skin, and respiratory tract;
  • Cough, sore throat;
  • Headache, drowsiness, dizziness;
  • Asphyxia; and
  • Unconsciousness.

Certain people may be more susceptible to these health effects during pregnancy.

Isoflurane is administered to animals predominantly by one of two methods: the use of a vaporizer system or an open-drop jar.

Steps to reduce your exposure to isoflurane via each method are outlined below:



Vaporizer System

  • Use of an induction box with a sliding lid instead of a hinged lid to reduce WAG release.
  • Flush the induction box with oxygen for approximately 10 seconds before opening the box and retrieving the animal.
  • Ensure a tight seal around the animal’s face when using a nose/face cone to deliver isoflurane. If you do not have a nose/face cone that is equipped with a diaphragm, one may be fashioned from a latex glove.

Open-Drop Jar

  • Use only for brief procedures lasting no longer than 1 minute.
  • Keep the jar at arms-length when opening it.
  • Use the smallest amount of isoflurane needed to achieve the intended results.
  • Do not perform this work in a standard biosafety cabinet or laminar flow hood as they are not intended for use with volatile chemicals.

Where to Learn More

Download this information sheet to learn more about each method. Please take a moment to review the Laboratory Standard Operating Procedure, SOP for Anesthetic Gases in Animal Research, published on the Department of Environment, Health & Safety (EHS) website. This document can be customized to fit your lab’s specific needs.

If you have any additional questions or concerns, please contact EHS at [email protected].

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