Naamfon,
Thank you for the information on ETO sterilization, I've been curious to learn more about the process.
My company uses quite a few spices and had formerly used ETO sterilization. However our products ship internationally and we had issues with the Australia, EU, and other international regulations so we worked with our supplier to switch to PPO sterilization (Propylene Oxide). I'm relatively new to the food industry and honestly don't know much about the PPO residue regulations, but supposedly there are less strict on PPO.
Dinu, if you have problems with ETO residue maybe consider PPO? (sorry on I'm not much help on more information regarding PPO)