May 11, 2017
When discussing leaks of sterilant chemicals such as ethylene oxide (EtO) or hydrogen peroxide, the first suspect of course is the sterilizer. In order to perform low temperature sterilization, i.e. the elimination of all microbial life, high concentrations of reactive chemicals are used. Obviously, if these get into the work space, they pose a risk to workers’ health.
However, often it is not the sterilizer that is to blame. Most modern sterilizers are very well engineered and though problems can occur, as with any equipment through wear and tear, mechanical failure or more commonly human error; leaks are commonly the result of other system failures.
This fact was brought home to me recently when I visited a hospital (outside the US) to monitor an EtO sterilizer. ChemDAQ has performed many gas monitoring studies in various markets. The monitors showed large readings each time the sterilizer was run, (~ 50 to 70 ppm) around the time expected for the sterilizer to exhaust its EtO. The initial suspect was of course the sterilizer, but further investigation found that similar concentrations of EtO were also found in the work area. The department had good air exchanges (we also measured them) and so clearly the EtO was not coming directly from the sterilizer. The most likely explanation is that the exhaust vent from the sterilizer was placed too close to the fresh air intake. We have seen similar situations in the US too, and we have also seen EtO leaks due to failed exhaust fans, and failed joints in the exhaust system.
For the leading EtO manufacturers, it is fair to say that the engineering controls probably contribute more to leaks that the sterilizers themselves do. Of course, it is not just EtO sterilizers that need good engineering controls; all low temperature sterilizers need good air exchanges/exhaust (see manufacturers’ instructions for use), then even the smallest leak becomes significant because the leak gas is not removed. However, whether a hazardous gas concentration is due to leak from the sterilizer, the exhaust or the failure of the exhaust, the impact is the same to the person exposed. The two common sterilant chemicals, EtO and hydrogen peroxide are imperceptible until well above dangerous levels and therefore it is important to ensure that there is a continuous gas monitor protecting workers in that area. Whether the sterilizer is to blame or not, everyone can relax and get back to work knowing they are protected with a continuous monitor.
If you would like more information on continuous monitoring, please contact us.