# From 5G to 6G--Challenges, Technologies, and Applications
## 3 Sixth-Generation Network's Aspects
### Sixth-Generation Network's Footprint
#### 3.1.3 Economic and Environmental Impact  
The economic and environmental impact of communication systems is usually overlooked, especially the toxic waste from electronics. Batteries for instance contain hazardous chemicals that are not eco-friendly if left in nature to decompose. Thus, one of the expected innovations with the arrival of 6G is a wider adoption of energy harvesting via radio waves or laser beams to realize battery-free devices [12]. Moreover, the exponential increase of devices connected to the Internet is partially responsible for the annual electronic waste increase. For instance, it has been reported that the yearly global amount of electronic waste reached a record high of 65.4 million tons in 2017, rising from 14 and 42 million, in 2005 and 2014, respectively [37; 38; 39]. To give some perspective on these figures, the amount of electronic waste generated in the year 2017 was roughly 11-times heavier than the Great Pyramid of Giza [40] or enough to stack a pile that can reach the Moon and back seven times. These numbers are constantly increasing, which is an alarming indicator for the health of the environment, especially as handheld devices and laptops contain toxic materials such as mercury, arsenic, and chromium [39]. Therefore, it is important to emphasize electronics' recycling in the international communication standards of 6G, improve the efficiency and performance of the disposal process, and spread awareness among consumers to participate in the recycling process. A possible direction for reducing electronic waste is fabricating chips using green biological materials, such as microbes [41], allowing for the recycling process to take place with less-toxic materials. Another potential benefit of considering green biological materials could be the reduction of energy consumption during the fabrication process. Moreover, with the trend of using higher and higher carrier frequencies, little attention is being paid with respect to the health implications. This was demonstrated in [42], where _millimeter_ waves were said to produce heat as a side effect of radiation, resulting in thermal hazards to the human body, such as eye and skin damage. Moving from the _millimeter_ waves' range to the \(near-THz\) range (100-900 GHz) raises even more questions about health concerns and the safe limits of radiation exposure. For example, the work in [43] examined in depth the health implications of terahertz frequencies on human tissues and cells and tried to answer the question about the safe limits of exposure to terahertz frequencies. Another example was given in [44], where the researchers studied the effect of high-intensity terahertz radiation on human skin fibroblasts and its long-term effects. Moreover, the work in [45] characterized the effects of terahertz irradiation on human morphology and macromolecules and conducted experiments with different terahertz sources of varying intensities. The work in [46] provided a comprehensive survey of the relationship between terahertz radiation and the effects on human skin and the potential use of terahertz radiation as a therapeutic tool in skin tissue. More research should be invested in this area to create acceptable standards and rigorous regulations for communication device manufacturers. The health implications do not stop here: although the advancement in network connectivity has come a long way in bringing individuals closer than ever before, this has also left many feeling isolated and depressed [47]. The sixth-generation network promises extended immersion experiences by new means such as nano-chip implants, and this calls for the need for thorough research to analyze the severity of the resulting social disorders. The communication range of terahertz frequencies should also be discussed, as the use of extremely high frequencies leads to low coverage [48]. This has the implication of limiting the use of terahertz frequencies to indoor communications only.