The dictionary defines “danger” as “the state of being exposed to harm : liability to injury, pain, or loss.” Typically, gas detection is deployed in areas that contain potential danger.
This danger may result from some sort of upset condition, as in a leak—representing an immediate toxic or explosive risk—or it could be more insidious, as in a long-term relatively low-level exposure to some toxic compound, devastating only in its cumulative effects.
Although many compounds list both occupational exposure limits and lower/upper explosive limits, in practice, there are few common hazardous gases that will present themselves as both toxic and combustible dangers. One of these is ethylene oxide (EtO). Even though the widest use of this chemical is in chemical syntheses, in terms of numbers of people affected, the health care related applications are of the greatest interest.
A case from the early 2000s serves to illustrate the dangers of EtO, and what can happen if those concerned—both on the user and regulatory sides—lose sight of this.
EtO is an essential sterilant, used on the many medical devices that cannot take the heat of steam. Despite the introduction of numerous processes that promised to replace EtO, none has. Indeed, Johnson & Johnson is still one of the world’s biggest health care consumers of EtO even though it also markets a sterilizer touted as a partial EtO replacement.
On 19 August 2004, at a contract sterilization facility in Ontario, California, mishandled EtO caused an explosion, that resulted in injuries to four employees, and damage to the facility that disrupted normal operations for nine months.
Brilliant and detailed investigative work on this incident was performed by the U.S. Chemical Safety and Hazard Investigation Board (CSB).
CSB’s webpage on the investigation is here
A very informative video, featuring forensic-quality animation, is available for live-streaming.
DVD copies of this program, and others created by CSB, are available on request.
After studying CSB’s materials, one will note that:
1. In general, all concerned seemed to be detached from the reality that EtO is explosive. During a maintenance procedure, a key aeration phase was bypassed, and shatter-resistant glass was not utilized in the control room windows overlooking the process. Indeed, every injury was caused by flying glass.
2. System designers were under the quite mistaken belief that monitoring pressure can substitute for gas detection.
3. In its zeal to protect us from “evil” EtO, California and certain other states continue to require the treatment of backvent EtO emissions, even though the Federal EPA (hardly an anti-Green organization) eliminated this requirement in 2001. That catalytic oxidizers—featuring live flames—are needed in this process doesn’t seem to bother anyone.
Therefore, in the minds of regulators, the very questionable “hazard” of venting EtO to the atmosphere, as could have been treated by the much safer chemical scrubber method, is somehow more important than the obvious risks of employing the catalytic method, which, in fact, catalyzed this explosion.
Lest we forget, the biggest danger involved in this entire enterprise is that if not properly sterilized, the medical devices can cause serious illness or death to hapless patients! Indeed, if EtO were used more, and the various alternative methods were used less, we could probably put a dent in the more than 100,000 deaths caused by in-hospital infections, that occur every year in the United States.
It is also well worth remembering that with technological solutions do come some potential dangers. No one argues that we should return to the horse and buggy, even if the gasoline in automobiles is dangerous. Users of gasoline are cautious, and understand the hazards involved.
Similarly, sterilization is a boon that drives beneficial invasive medical care. EtO and other potentially dangerous chemicals can be handled safely, but only if both the users and the regulators understand the dangers, and impose logic, right reason, context, and perspective on the methods involved.
