In the near future the American and Canadian governments are expected to lower the TLV for ethylene oxide to 10 ppm or even lower. (The TLV or Threshold Limit Value is now 50 ppm for 8 hours or 75 ppm for 15 minutes.) The reason for this proposed change is that ethylene oxide is considered to be more toxic; it is now a recognized mutagen and is suspected to be a carcinogen.
Ethylene oxide is capable of diffusing and penetrating rapidly through most material. It was believed that this would result in a quick loss of any residual ethylene oxide after the objects are removed from treatment. Also, it was known that rubber and some plastics could retain absorbed ethylene oxide for a long period of time. Tests have now indicated that most materials will retain some ethylene oxide and release it slowly following fumigation. The uncertainties are: a) how much ethylene oxide is retained and b) how much time is required for it to dissipate. At the present time, no definite time periods can be given for the aeration. To insure personnel safety, any unnecessary exposure to the gas must be avoided; only by monitoring the concentration of the gas can this be carried Out.
This information comes from the IIC-CG Newsletter for December, p. 8-11, a technical note contributed by John E. Dawson, Conservation Scientist, Environment & Deterioration Research, Canadian Conservation Institute, 1030 Innes Rd., Ottawa, Ontario, Canada KlA 0M8. Canadian sources for monitors are mentioned: Matheson (about $200); Safety Supply Canada, no price given; Bacharach (about $2,500).
The Occupational Health and Safety Products Division of 3M has a mew monitor for this purpose, the "Ethylene Oxide Monitor 3550." It can be clipped to the lapel or positioned in an area, and sent to 3M at the end of the shift for analysis, which is reported within five days. Cost of analysis is included in the purchase price. For details call 3M's OH & SP Technical Service, 612/733-6234.
Readers who are aware of any other sources of monitoring devices are invited to report them to the Newsletter so they can be reported in a follow-up notice.
Detailed instructions for prolonged aeration of the objects and chamber, and for personal protection, are in the IIC-CG's December Newsletter for December. For a copy, write IIC-CG at P0 Box 9195, Terminal, Ottawa, Ontario, Canada KIG 3T9.
The CCI is investigating aeration of ethylene oxide this year.
Ethylene oxide was last covered in this Newsletter in July 1980.