An animal care technician enters the freshly decontaminated animal room to prepare housing for the new colony. Almost immediately, her nose and throat feel a tingling irritation, then she begins coughing and feeling a shortness of breath. Within a few minutes, she begins experiencing a stinging sensation on her skin and her eyes are watering and burning to the point that seeing is difficult. She is trying to find the door out and thinking that she didn’t see or smell anything out of the ordinary upon entering the room. What went wrong?

Vapor phase hydrogen peroxide decontamination technology is relatively new, having been available since 1991.1Vaporized hydrogen peroxide (VHP) or hydrogen peroxide vapor (HPV) is gaining popularity and we are seeing rapid expansion of its use for everything from biological safety cabinets to animal rooms. In fact, the May/June 2006 issue of Animal Lab News had a good article on hydrogen peroxide vapor equipment decontamination that discussed efficacy, material compatibility, and some of the pros and cons of HPV compared with formaldehyde, a widely used sterilizing agent with many associated hazards.

Most of us have heard of hydrogen peroxide and have probably purchased it occasionally at the local pharmacy. Maybe, your mom used it to clean out a small wound, cut, or scrape when you were a child. The over-the-counter (OTC) product is typically sold as a 3% aqueous solution. The product used in vapor phase hydrogen peroxide decontamination is much more potent. Hydrogen peroxide used in typical VHP decontamination processes is greater than 30%, or at least ten times stronger than the OTC product. The concentrated hydrogen peroxide is vaporized in self-contained portable generators using proprietary and patented methods. These generators are available from a few different companies and in several configurations that depend upon the size of the room or equipment to be decontaminated. Most applications involve sterile manufacturing and/or packaging of pharmaceuticals or medical devices where the VHP generators are relatively small and operate in a closed-loop system. The goal here is to prevent contamination of products from environmental microorganisms.

Research applications can run the gamut from decontaminating tools or equipment before removal from BSL-3 or 4 laboratories to entire rooms. Work usually involves pathogens and the primary concerns are to protect the researchers and prevent cross-contamination between experiments. Reduction of environmental microbial contamination can also be targeted in cases of care and breeding of specific pathogen-free (SPF) animals. When large rooms are decontaminated, the ventilation system is used to maintain the desired pressure balance and to aid the decontamination cycle. Usually, the fresh-air make-up is shut off, and in many cases, the air handling system is used at the end of the cycle to flush out the room. Regardless of the configuration and construction materials used, the room must be well sealed during decontamination to prevent exposures to workers in adjacent areas.