Decontaminating infectious laboratory waste by autoclaving

The temperature profile of infectious laboratory waste being autoclaved was examined relative to the type of containers used in the process. A standardized waste load (1,750 +/- 4 g) placed in the container was evaluated by using a direct readout thermocouple. The sensor of the thermocouple was placed within an unused and outdated agar plate, centrally located about 5 cm from the bottom of the container. The gravity displacement autoclave tested reached 121 degrees C within 3 min. Waste within a steel container (plus 1 liter of water) reached 108, 120, and 122 degrees C at 12, 30, and 50 min, respectively. Without the addition of water, the corresponding temperatures were 60, 110, and 120 degrees C, respectively. With a steel container, "autoclavable" plastic bags, and no additional water, the temperatures were 36, 71, and 105 degrees C, respectively. When 1 liter of water was placed in the autoclavable bag, the temperatures were 98, 115, and 121 degrees C, respectively. Waste within a polypropylene container (dimensions similar to those of the steel container) with and without the addition of 1 liter of water, reached a maximum temperature of 108 degrees C at 50 min. With a polypropylene container, autoclavable plastic bag, and 1 liter of water, the corresponding temperature was 99 degrees C. Without the addition of water, the temperature was 92 degrees C. The importance of container, moisture, and material in autoclaving was demonstrated.