Less harmful electromagnetic waves

[ductrungvn]

Hi guys,
I am too old to remember basic knowledge about electromagnetic waves :D
I am looking for a combination of an electromagnetic wave and a material such that the wave can pass through human tissues, but it is blocked by the material. All I know is that X-ray/gamma can penetrate human body but is absorbed by metals/lead. Are there any such other combination which are less harmful than X-ray. I have gone through Wikipedia for few hours but still have not found the answer yet.
Could you please help me.
Thank a lots.

 

[phyzguy]

Radio waves pass easily through the human body, but are blocked by an appropriate thickness of metal (or any conductor).

 

[ductrungvn]

Thank you for the answer!
But I think radio waves are able to diffract around the object, is that right?