RESULTS •Surgery #1: ~3.5 hour surgical procedure conducted in a non-externally vented biosafety cabinet with passive scavenging system. Procedure yielded an average of 1.4 ppm*. This value is below Cal/OSHA but exceeds Genentech action levels.**

•Surgery #2: ~4 hour surgical procedure conducted in an externally vented biosafety cabinet in combination with passive scavenging system. Procedure yielded an average of 0.66 ppm*. This value is less than both the Cal/OSHA and Genentech action levels.**

•Surgery #3: ~1.25 hour surgical procedure conducted in an externally vented biosafety cabinet in combination with an active scavenging system (sliding-lid induction chamber and non-rebreathing circuit connected to FilterMate™ exhaust). Procedure yielded an average of 0.12 ppm*. This value is less than both Genentech and Cal/OSHA action levels.**

*As calculated from analysis of Chemdisk™.

**Cal/OSHA has established a Permissible Exposure Limit (PEL) of 2 ppm isoflurane based on an 8-hour time-weighted average (TWA). Genentech has a more aggressive PEL, using 50% of the Cal/OSHA action level (1 ppm).

Improving Occupational Safety by Reducing Isoflurane Exposure EffectsEric Cheng, RLATG, RVT, Joshua Tanguay, LAT, Diana H. Peroni, CIH, Janeko Bower

Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080

METHODSAn initial surgical procedure was conducted to obtain baseline waste gas recovery values. The surgical workstation consisted of a non-externally vented Class II A2 biosafety cabinet, portable anesthesia system, and a passive gas scavenging system. The average room air exchange rate was ~20 changes/hour. Mice were induced in 2 L hinged induction chambers using isoflurane in oxygen (1 L/min) delivered via a precision vaporizer (set at 2.5%). Surgeries were performed while anesthesia was maintained via non-rebreathing circuits. WAG was passively scavenged through activated charcoal canister filters. Air sampling for isoflurane was conducted using ChemDisk™ 574 halogenated anesthetic gas monitors. The monitor sampled workplace air by diffusion of halogenated anesthetic gases. These gases are collected on the media via adsorption. Three personnel monitor samples were used to detect for possible contamination. These samples were closed upon conclusion of isoflurane use, with start and end times recorded and sent to Assay Technology for analysis. Monitoring sessions were repeated as new engineering controls were implemented.

ACKNOWLEDGEMENTS•Genentech Environmental Health and Safety•Genentech Laboratory Animal Resources •Genentech In Vivo Pharmacology Research Staff•VetEquip, Inc.

DISCUSSION (Cont’d.)In the initial setup, there are three main areas of concern where WAG can escape the anesthetic system:•When opening the hinged-lid induction chamber.•Face/port interface of non-rebreathing circuit.•Passive scavenging via charcoal canisters.

By upgrading components to an active waste gas scavenging system, WAG exposure levels were minimized addressing employee safety needs.

Below is the refined surgical setup.

SUMMARY AND CONCLUSIONSBased on our results, an anesthetic system with usage of proper engineering controls can:• Minimize WAG exposure levels during

surgical procedures.• Help reduce health risks associated with

low-level exposure to WAG.

Reducing WAG leakage may also contribute to:

• Improved animal induction times.• Improved maintenance of surgical plane.• Overall decrease in procedure duration.

Results from our monitoring efforts have led to investment of necessary equipment to limit isoflurane waste gas exposure to in vivo staff.

INTRODUCTIONIsoflurane is a common inhalation anesthetic agent used in laboratory animal science and veterinary clinics. The release and exposure of waste anesthetic gas (WAG) in the work environment is an occupational hazard for staff working with this agent. Chronic, low-level exposure to WAG has been linked to increased incidences of neurologic and reproductive dysfunction, hepatic and renal toxicity, and neoplasia1. The Environmental Health and Safety team monitored anesthetic procedures to assess isoflurane waste gas exposure to in vivo research personnel and to address methods of reducing these levels. Through a series of large-scale mouse surgical procedures, industrial hygiene monitoring was conducted to characterize WAG exposure among the surgical staff. MATERIALS•Hinged-lid Induction •Mapelson E Circuit • Activated Chamber Charcoal Canister

•Sliding-lid Induction •FilterMate™ Exhaust •ChemDisk™ 547Chamber

DISCUSSIONThe major contributing factor to anesthetic pollution is inadequate scavenging of WAG. Our initial surgical setup using passive waste gas scavenging via activated charcoal canisters within a non-externally vented biosafety cabinet yielded higher than recommended PEL.

Below is the initial surgical setup highlighting areas of WAG leakage.

REFERENCES1.Smith, J. C. & Bolon, B. (2003). Comparison of Three Commercially Available Activated Charcoal Canisters for Passive Scavenging of Waste Isoflurane during Conventional Rodent Anesthesia. JAALAS, 42(2), 10-15.2.Smith, J. C. & Bolon, B. (2006). Isoflurane leakage from non-rebreathing rodent anesthesia circuits: comparison of emissions from conventional and modified ports. Laboratory Animals, 40, 200-209.3.DHHS (NIOSH) Publication Number 77-140, March 1977. Occupational Exposure to Waste Anesthetic Gases and Vapors, pages 29-35, 107-108.

#P125

Non-rebreathing Circuits

Hinged-lid Induction Chambers

Activated Charcoal Canisters

FilterMate™ Exhaust

Non-rebreathing circuitswith finger cots

Sliding-lid induction chambersconnected to FilterMate™

Circuit tubing connectedto exhaust via collector

Surgery Surgeon #1 Surgeon #2 Surgeon #3 Avg. Notes

1 1.5 NA 1.3 1.4 Non-externally vented biosafety cabinet

2 0.73 0.63 0.63 0.66 Externally vented biosafety cabinet

3 0.11 0.16 <0.1 0.12 Externally vented Hood + Active scavenging system

Results are an 8-hour TWA, ppm