Why it is safe to use ETO


The Anprolene and EOGas sterilising cabinets from Andersen Products are designed to ensure safety for operators. They comply will the strictest regulations governing the use of Ethylene Oxide in a work environment. This section explains why it is safe for operators to sterilise medical devices using one of Andersen Products' sterilisers.

Pump system

The key design element that ensures safety is the negative pressure cabinet. There is no gasket on the door. It is designed to let the vent pump draw air into the cabinet, over the liner bag containing the gas and items being sterilised, and out through the exhaust at the back. The two pumps in the top of the steriliser keep cabinet pressure below room pressure ensuring that gas can only escape through the ventilation tube.

A very small quantity of gas

Andersen sterilisers use very small quantities of EtO. The largest ampoule holds only 17.6 g. Once the ampoule has been snapped there are 11 minutes before the gas will start to come through, giving the operator plenty of time to close the steriliser and select a cycle.

See also "What happens if you break an ampoule by accident outside the steriliser?" below.

Aeration system

The sterilisation cycle is always followed by an aeration cycle designed to remove all ethylene oxide residues from the sterilised devices. Gas is pumped out for 2 minutes and then fresh air in for 2 minutes for the whole duration of the aeration period, ensuring that when the steriliser is opened by the operator exposure is below limits. Sterilisation and aeration take place in the same cabinet. The operator can also choose to leave the devices to aerate for some extra time, beyond the minimum aeration period, either in the cabinet or in well ventilated room.

Exhaust system

EtO in the exhaust line will generate completely undetectable levels of gas in the local atmosphere. This gas will react with water to form Ethylene Glycol, which is itself bio-degradable.
EtO is not covered by any of the international treaties on release of chemicals into the environment. It is not an ozone depleter (Montreal protocol) or a VOC (Geneva protocol) or a greenhouse gas (Kyoto protocol). Nor is it covered by the European Pollution, Prevention and Control regulations. Even in the USA there are no restrictions covering emissions up to 1 tonne per year. The very small quantities used in Andersen cabinets may be released directly into the atmosphere, where it reacts with water and organic material in a completely biodegradable way.


To ensure correct use we offer Key Operator Training for all users of the cabinet at a customer, for the lifetime of the cabinet. The training consists of a study guide to be read and then a test paper for you to complete. And, clearly you can have the study guide open beside you as you do this. Then you send the test paper to us and provided it is clear you have read the study guide we will arrange a telephone interview which will go over the essential information again. Our founder, Dr Harold Andersen, did a first degree in Psychology and he set this up this way because the knows that if you have read this material, then written it and then spoken it, you will remember it.

Anprolene Key operator training EOGas Series 4 Key operator training

These are the answers to the questions that operators most frequently ask:

What happens if you break an ampoule by accident outside the steriliser?

The EOGas ampoule is supplied in a special plastic cartridge and can only be activated by pressing a trigger button. The Anprolene vial is wrapped in a special paper that prevents it from breaking if accidentally dropped. If you find yourself in a situation where the ampoule has been activated outside the steriliser, you simply need to place it in the sterilisation cabinet and start a cycle. The gas will be evacuated to the outside through the exhaust pipe.

What happens if there is a power cut during a sterilisation cycle?

The program in the microchip is protected from power loss by a battery which is built into the clock chip mounted on the circuit board. The design enables the program to continue in the event of a power loss by using the backup battery power.

How can I control the ETO exposure in my work environment?

Personnel exposure to ethylene oxide can be monitored by using personal exposure badges such as the Andersen AirScan badges. Two AirScan badges are available: The Short Term Exposure Limit (STEL) 15 minute badge and the Permissible Exposure Limit (PEL) 8 hour badge. The STEL badge is to be worn by the operator for 15 minutes during the time period when the greatest exposure to ethylene oxide is likely to be encountered, which usually occurs when unloading the steriliser. The PEL badge is to be worn by the operator for 8 hours during a normal working day in which gas sterilisation occurs. The day chosen must include at least one unloading of a sterilser. EtO exposure levels should be checked upon installation of the steriliser.

Order AirScan badges