Most, almost all animals are mostly water. About 2GHz you have a frequency that resonates with water, it's gets stopped by water, including rain. E.g. it's energy goes into the water, this is how the microwave operates.

For this reason it's traditionally considers useless as radio transmission. And turned into a global free frequency span. Making this radio space used by all kinds of devices that you have at home. Wifi, Bluetooth, etc. There is tons of research of how radio and other waves effect the human body.