It is not clear to me exactly what you are referring to, so I will try to give some helpful information.
If you want to know for sure that something is “safe”, it turns out that absolutely nothing is absolutely safe. Every object in your environment, even non-objects, such as ideas and opinions, can be very dangerous. It depends on how people use them. Clean, pure drinking water can be lethal if you drink too much at one time (water toxicity).
You can apply the absolute strictest standards for safety testing, and still end up with many things that are definitely not safe. Just look at the many drugs and devices that have been pulled from the market after FDA approval. You can visit fda.gov to see many pages pf dangerous drugs and devices that had been extensively tested and approved previously as “safe”.
So, safety is largely a question of human behavior, not an inherent property of any object.
A better approach is to ask if something is dangerous. Things can be inherently dangerous. This is not so much a result of human behavior. It is inherent to the device itself. When we ask this question: “Is PEMF inherently dangerous”, we find that there are thousands of publications, many clinical reports, millions of people who use PEMF, spanning more than 6 decades, but a startling total lack of any reports of harm being done by PEMF. That does not prove that it is “safe”, that just suggests strongly that it is not inherently dangerous. There do not seem to be any known significant risks with PEMF.
However, the bottom line is this:
All medical devices, procedures, and drugs have risks, some more than others.
If you are not comfortable with those risks, DO NOT USE THEM. That is your decision.