Can Steam Autoclaving be a Possible Alternative to Incineration?
Steam autoclaving is a procedure that uses steam, heat, and pressure to inactivate microorganisms and sterilize medical tools (Schipanski, 1969). It was considered to be one of the newest and best alternatives to treat medical waste other than incineration. The U.S. Environmental Protection Agency reported that over 90% of the infectious medical waste was treated by incineration before 1997 (EPA, 2016). However, it was found that incinerator emits toxic pollutants that are detrimental to the environment and human health. Dioxin is a typical example of hazardous emission which can lead to birth defects, cancer, diabetes, and immune system disorder (Cole, 1997). Ineffective medical waste management can cause serious public health problems. For instance, improperly transporting mix wastes to open dumpsite can cause soil and groundwater pollution, which may lead to sickness in humans and species living around the disposal site (Su, 2005). For this reason, researchers have been very interested in investigating alternative methods for medical treatment in terms of more cost-effective and safer disposal practices.
As far as medical waste autoclaving is considered to be a relatively new medical waste disposal method, it was actually invented in 1965 by Emil R. Schipanski. An autoclave was designed to accomplish sterilization by inactivating bacteria under steam pressure in a closed chamber (Schipanski, 1969). The procedure would require a shorter time if a higher temperature is applied, or a longer time if a lower temperature is applied to sterilize a population. The optimal condition for sterilization was determined to be at 121 °C and 131 °C for 60 and 30 minutes, respectively (Hossain et al., 2012). Recent studies have found that autoclaving is very advantageous in various ways. It does not require the input materials to change its physical forms whereas incineration burns waste into ashes and gas. Medical tools that were autoclaved can be either recycled and reused again or safely transported to landfills (Hossain et al., 2012). Autoclaving is also found to be more cost-effective than incineration on an economic scale. Although the capital investment to install an autoclave might be triple the price of an incinerator, this loss can be regained through its low maintenance fee and energy consumption. It is also simpler and safer to operate, which can reduce the chance of health care workers getting injured from the handling process (Ferdowsi et al., 2010). The Bio-Medical Waste Rules of India highly recommended using autoclaves to disinfect and treat infectious bio-medical waste (Government of Indian, 2016).
Table 1. The comparison of costs for autoclave and incineration. Table taken from Ferdowsi, 2010.
Steam autoclaving also has several disadvantages. Autoclaving was found not suitable to treat laboratory chemicals, organic solvents, anatomical, pathological, bulky, low-level radioactive, and chemotherapy wastes (Al-Khatib et al., 2009). In addition, the unexpected regrowth of bacteria on sterilized medical tools has been overlooked by many people. A recent study tested the effectiveness of steam autoclaving in deactivating 6 types bacteria. 3 Gram-positive and 3 Gram-negative bacteria were cultured in medical-waste-like environments and autoclaved. All bacteria were found to be inactivated during day zero and day one after the treatment. However, Gram-positive bacteria started regrowing two days after the treatment. After six days, the regrowth of all the bacteria appeared in sterilized tools. This finding indicated steam autoclaving’s failure in achieving sterilization and the results refuted autoclaving as an alternative to incineration (Hossain et al., 2012).
Table 2. Re-growth of bacteria in sterilized waste. Table taken from Hossain et al., 2012.
Although the public is awared of the potential of incineration to emit harmful pollutants, the difficulty of finding a flawless alternative keeps incineration as a popular method of medical waste disposal treatment. Autoclaving does have various advantages such as its cost effectiveness and its potential to have medical waste recycled and reused. However, the failure of its primary goal in sterilization outplayed the advantages. It can only deactivate microorganism for a short period of time whereas incineration is more powerful in eliminating infective agents. Thus, steam autoclaving should not be recommended as a replacement of incineration.
Work cited
Government of India and Ministry of Envirnoment, Forest and Climate Change. (2016). Bio-Medical Waste (Management and Handling Rules). Gazette of India, Extraordinary, Part II, Section 3, Sub-section (i).
Schipanski, E. (1969). Autoclave. US patent.
U.S. Environmental Protection Agency. (2016). Medical Waste. Retrieved from https://www.epa.gov/rcra/medical-waste
