CDPH, NIOSH Address Veterinary Workers' Exposure to Anesthetic Gas

Published June 27, 2019

A new workplace hazard update (PDF) issued by the Occupational Health Branch of the California Department of Public Health warns that anesthetic gas may pose health risks to veterinary workers. The document focuses on isoflurane, an anesthetic gas commonly used in veterinary practice. According to CDPH, increasing evidence from laboratory animal studies shows that exposure to isoflurane may cause harm to workers’ nervous or reproductive systems. In laboratory animals, reported effects of exposure to isoflurane include nerve cell damage, learning and memory impairment, abnormalities in offspring exposed during pregnancy, and reduced sperm production and impaired sperm health. In humans, acute exposure to isoflurane has been associated with skin and eye irritation, headache, drowsiness, and dizziness. CDPH urges veterinary staff and facility owners to protect workers from this hazard.

OSHA does not currently have permissible exposure limits regulating isoflurane and other inhaled anesthetic agents. The agency’s guidelines for workplace exposures to anesthetic gases were most recently revised in 2000. The Cal/OSHA PEL for isoflurane is 2 ppm averaged over an eight-hour day. NIOSH does not have a recommended exposure limit specific to isoflurane, but a 1977 criteria document includes RELs for both nitrous oxide and halogenated agents such as chloroform, trichloroethylene, halothane, methoxyflurane, enflurane, and fluroxene. Isoflurane, a type of halogenated anesthetic gas, was not introduced until the 1980s. The 1977 document proposed an REL for halogenated waste anesthetic gas of 2 ppm in a one-hour period. Earlier this year, ACGIH added isoflurane to its Notice of Intended Changes list, which indicates substances and agents for which a limit is proposed for the first time.

According to NIOSH, the 1977 REL for halogenated gases has been applied to isoflurane and other newer halogenated ethers in research studies and clinical applications “because of the lack of established OELs for these agents and lack of research on chronic health effects.”

CDPH’s hazard update follows a report (PDF) recently published by NIOSH that details the agency’s health hazard evaluation of waste anesthetic gas exposure at a veterinary hospital. Employees at the hospital were concerned that waste anesthetic gas exposures were causing adverse reproductive effects among workers. Isoflurane was the primary anesthetic gas used during surgeries at the veterinary hospital. NIOSH investigators found that one employee was exposed to isoflurane levels in the air above the REL for waste anesthetic gas while attending to a dog as it recovered from anesthesia after surgery. According to NIOSH’s report, anesthetic gas remains in animals’ exhaled breath after surgery, and veterinary technicians’ faces are usually close to animals’ faces post-surgery to assess their level of alertness. The agency’s evaluation could not link employees’ reported miscarriages to their work at the veterinary hospital, but NIOSH urged the employer to address other tasks that present potential reproductive hazards, including the handling of hazardous drugs, being in the X-ray room while radiographs are taken, and sterilizing instruments using ethylene oxide, which has been linked to miscarriage.

More information on veterinary worker safety and health is available from NIOSH’s website.