Near the beginning the article states:

> After reading many animal toxicology studies that found that this radiation could increase oxidative stress — free radicals, stress proteins and DNA damage

Not knowing enough about chemistry, I could imagine the radiation being able to affect some of the weaker bonds in certain chemicals, breaking them, and creating more energetic new compounds. This could be damaging to among other things, DNA.

I know the photo-voltaic effect means there is a certain threshold frequency needed to be able to affect such bonds. I have no idea whether there are any chemical bonds that can be affected by say 5.8Ghz radiation. (Highest frequency non 5G phones should be emitting)