The biggest concern is the high-frequency radio waves (mmWave). The 5G network will operate near the highest frequencies. Lower down are the wireless networks that our current smartphones use, as well as the wireless connection at our homes, and offices. The millimeter-wave spectrum has never been used for telecommunications. The reason is not because of the unknown dangers but rather the impracticality – it is not that effective at long distances. Or if there are any obstacles along the way, such as buildings, trees, and even people.
Before we continue, check this diagram from Wikipedia:
Dangerous: on the right. Safe: on the left. Source: Wikipedia
It clearly shows the difference between the two types of radiation – ionizing and non-ionizing. The first one includes gamma-rays, UV rays from the sun and X-rays. They are dangerous to our health because they can penetrate the human body and break apart its atoms.
Every single communication frequency used until now, including the spectrum for mmWave that the 5G network will use the most, is in the non-ionizing part of the spectrum.
So, what is the problem then? The lack of consensus. The thing is that according to some reports and tests, the radio-frequency waves like the kind that emanates from cell phones are drastically raising the risk of cancer. One of these reports is made by the National Toxicology Program (NTP) and is based on their research in which a group of rats was exposed to RF (radio frequency) and they developed malignant tumors. Well, this is the part that all of the anti-5G groups are talking about.
Original Source: https://www.scalefocus.com