Abstract
The residual toxicity of formaldehyde gas (FG) sterilization and neutralization equipment, "Holl Steri" (Asuka Medical), was evaluated biologically and compared with the conventional ethylene oxide gas (EOG) disinfectant process. The percentage of FG group motile spermatozoa, preserved in 0.25 ml straws for 6 hours, compared with the non-sterilized control group, decreased significantly (p<0.01) in the 6th hour. However, FG group had significantly higher survival rate than EOG group (2nd hour : p<0.01 ; 4th hour p<0.05). In bovine embryo culture for three days, the embryo survival rate decreased significantly (p<0.01) in FG group compared with control group of gamma ray sterilization on the 2nd day, and, at 2.5 days, all embryos were nonviable. However, compared with EOG group, embryo survival rate in FG group was significantly (p<0.01) higher on the 1 st and 2 nd days. In the in vitro maturation, fertilization and culture system of bovine oocytes for about ten days, the division rates into five or more-celled embryos and the blastocyst generation rates in FG group and control group of gamma ray sterilization were 60.0, and 20.0%, and 65.0 and 36.7%, respectively. Although rates were a little lower in FG group, there was no significant difference between groups. On the other hand, there was no embryonic growth in EOG group. These results suggest there was slight residual cell toxicity with FG sterilization and neutralization equipment compared with non-sterilizing or gamma ray sterilization, however there was very little residual toxicity compared with the widely employed conventional EOG sterilization.
