The trouble is, there's lots of evidence, and also lots of evidence that it isn't. The only way to draw a conclusion is by making a judgement about which evidence is better: which scientific experiments are better designed?
You can also analyze the plausibility of the arguments. Cell phones do not produce ionizing radiation.
This is similar to homeopathy. Even if the state of research is not great, we're discussing a theory that is just not physically plausible. The default assumption should be that it is wrong.
