# Life Cycle Assessment of Medical Waste Management: Case Study for Istanbul
## Freshwater Aquatic Toxicity Potential [%]
### Human Health Toxicity Potential  
The main contributors to human health toxicity potential are the emissions of sulfur dioxide and heavy metals from the incineration process [36]. As seen in Figure 13, there is a similar trend in this compact category to that for freshwater aquatic toxicity. Scenario 1 has the highest impact, followed by scenario 3, scenario 0, scenario 2, and scenario 4. This situation is attributed to the amount of waste incinated and the concentration of toxic gases emitted. The lowest impact on human health toxicity potential is 112.31 kg DCM-Eq, corresponding to 3.99%, whereas the impact value of 1336.16 kg DCM-Eq is the highest, corresponding to 48.41%. This situation is supported by the studies in [25; 35], which reported a greater contribution to human health toxicity impact from incineration compared to that from landfill.  
It can be seen in Table 2 that scenario 4 (waste segregation at the generation point/waste minimization + incineration + sterilization + landfill) presents the best environmental performance, with 14.21% of the impact value, among all scenarios. Additionally, scenario 4 has the least impact on human health toxicity, freshwater aquatic toxicity, and acidification categories. There is a slight increase in global warming, eutrophication, and ozone layer depletion compared to the baseline scenario. This situation is attributed to a higher amount of waste being transported to the landfill site; therefore, the amount of waste incinated or sterilized is decreased by separating non-hazardous municipal solid waste and medical waste and minimizing hazardous medical waste. Unfortunately, waste segregation at the generation points results in an increase in the amount of non-hazardous municipal solid waste transported to the landfill. Therefore, it is highly recommended to take reuse, recovery, and recycling processes into account in the medical waste management system and to limit the amount of waste sent to landfill sites [35], resulting in a reduction in methane emissions as well as a decrease in adverse impacts on the global warming, eutrophication, and ozone layer depletion categories.  
On the other hand, the total impact ratio obtained in scenario 1 (incineration + landfill) is 29.79%, the highest, which is worse than that in the baseline scenario (the current medical waste management system in Istanbul). However, scenario 1's global warming impact is the lowest at 14.4%. This situation is attributed to less methane emissions from the landfill site. Thus, it is recommended to invest in the sterilization process. Emissions from incineration present adverse effects on many environmental impact categories. Therefore, the incineration process should be considered the last resort, used when there are operational issues in the landfill and/or energy cannot be generated from landfill gas.  
Figure 13: The distribution of human health toxicity potential.  
Finally, regulators of medical waste management in Istanbul should consider building sterilization and/or incineration plants on the Asian side to reduce the detrimental environmental impacts and the cost of transportation. In this context, sterilization should be preferred rather than incineration.