Kinetics of the aeration of ethylene-oxide sterilized plastics.
The aeration of ethylene-oxide (EO) sterilized medical plastic materials is dealth with mathematically, and subsequently the model found is used for calculation of the EO diffusion coefficient in various plastics with the composition and temperature as variables. Absorption and dissolution of EO in various plastic materials are measured at varying concentrations of EO, temperatures and compositions of plastics. The mathematical model is used to evaluate the EO desorption from medical devices under different physico-chemical conditions as well as in vivo. EO analysis methods are evaluated on the basis of the model and are compared with experimental results.
Ethylene oxide sterilization in the medical-supply manufacturing industry: assessment and control of worker exposure.
OBJECTIVE
In 2005, the Taiwan Institute of Occupational Safety and Health started an on-site consulting program for the medical supplies manufacturing industry, which use ethylene oxide (EO) as a sterilant, with the goal of enhancing occupational hygiene practices and controlling EO-related risks. This study presents EO exposure assessment results and examines the effectiveness of control measures.


METHODS
Detailed surveys, including exposure monitoring, were conducted at 10 factories. Airborne EO was collected using an HBr-coated charcoal tube and analyzed using GC/MS.


RESULTS
Sterilizer operators had an average short-term EO exposure level of 27.61 ppm during unloading; mean time-weighted average workshift exposure was 7.35 ppm. High EO concentrations were also present throughout the facilities. Specifically, mean EO concentrations in the aeration area, near the sterilizer and in the warehouse were 10.19, 5.75, and 8.78 ppm, respectively. These findings indicate that immediate controls are needed, and that EO emissions from sterilized products during storage cannot be overlooked. Worker short-term exposures during unloading was inversely correlated (p < 0.05) with the numbers of poststerilization purge cycle applied. The specific controls implemented and their usefulness is discussed.


CONCLUSION
Increasing the number of poststerilization purge cycles is a simple approach to eliminating extremely high exposure during unloading. Improvements to ventilation, particularly in the aeration area and warehouse, were also effective in minimizing worker exposures. Use of effective respirator is recommended until the EO exposure levels, averaging 3.41 ppm after the controls, fall below the permissible exposure limit.
Tissue reactions to 2-chloroethanol in rabbits.
Abstract 2-Chloroethanol is a potential reaction product between ethylene oxide and a free chloride ion. Certain plastic devices, such as those of the polyvinyl chloride types, contain such free chloride ions and are often sterilized by ethylene oxide. Depending on the chloride ion content and residual ethylene oxide, varying amounts of 2-chloroethanol (a chlorohydrin) may be formed as the reaction product. Since this agent is less volatile than the ethylene oxide, standard degassing procedures may leave residual 2-chloroethanol in the plastic device. If these devices come into prolonged contact with tissues, as might occur with tracheotomy tubes, the possibility exists for tissue damage from leaching 2-chloroethanol. This paper reports on the effect of pure 2-chloroethanol, and various dilutions of this material, on several of the tissue types with which a tracheotomy tube might come into contact in a patient. It was found that pure 2-chloroethanol is quite destructive to most of the tissues, including ophthalmic, mucosal, muscular, and subcutaneous tissues; however, on dilution, the toxicity potential decreased sharply. dilutions of 1:10 were still toxic, but in most cases, dilutions of 1:100 were practically innocuous. A cell culture evaluation correlated almost perfectly with in vivo techniques.