Characterization of Waste Anesthetic Gas Exposures to Veterinary Workers in the Tampa Bay area

Veterinarians routinely conduct surgical operations on animals while veterinary technicians administer anesthetic gas to sedate the animal prior to an operation. One commonly used anesthetic agent in veterinary clinics is isoflurane. Veterinary workers have the potential to be exposed to this gas during surgical operations. The Occupational Safety and Health Administration (OSHA) does not have a specific Permissible Exposure Limit (PEL) for isoflurane, however The National Institutes for Health (NIH) does advise that workers should not be exposed to isoflurane in concentrations exceeding 2 parts per million (ppm) for an 8 hour Time Weighted Average (TWA). Animal clinics vary in the amount of surgeries they perform. Some clinics specialize in surgical services and therefore conduct a high volume of surgeries, while others that perform general practice work may conduct a far lower volume of surgeries. The research objectives for this study were to determine if veterinary workers are exposed to isoflurane levels above the concentration recommended by NIH and to quantify any disparity that exists between worker exposures at two veterinary facilities. A portable infrared ambient air analyzer (Miran SapphIRe, XL, ThermoScientific) was used to measure area concentrations of isoflurane and sorbent tube sampling via OSHA Method 103 was used to determine personal exposures to isoflurane. For the three days that sampling took place at the low volume clinic, personal sampling (samples taken in the breathing zone of a worker) during surgery showed that isoflurane concentrations exceeded the NIOSH recommended limit for 3 of the 5 samples when assuming a 6-hour gas exposure. When assuming exposure only lasted for the 2 hours that sampling occurred, 1 of the 5 samples exceeded the NIOSH recommended limit. For the three days that sampling was conducted at the high volume clinic, none of the 6 samples taken exceeded the NIOSH recommended exposure limit. The average isoflurane exposure to workers at the high volume clinic was 1.72 ppm while the average for the low volume clinic was 3.77 ppm. The average isoflurane exposure for veterinarians was 2.05 ppm and the average for veterinary technicians was 3.16 ppm. These data provide evidence that veterinary technicians may face higher exposures to isoflurane gas than veterinarians. There is also evidence that workers at the low volume clinic may be exposed to greater concentrations of isoflurane than workers at the high volume clinic. The average isoflurane concentrations were lower for the high volume clinic likely due to the fact that they relied only on an injectable sedative and no delivery of anesthetic gas for most operations. The high volume clinic also used more sophisticated equipment than the low volume clinic for the capture of waste gases