I'm confused as to how millimeter wave can be first described as not being able to "travel very far, and they’re blocked by fog or rain, trees and building mate

I'm confused as to how millimeter wave can be first described as not being able to "travel very far, and they’re blocked by fog or rain, trees and building materials" and "largely absorbed in the skin" and them immediately after "this radiation may cause hypersensitivity and biochemical alterations in the immune and circulatory systems — the heart, the liver, kidneys and brain" - how is the radiation penetrating deep enough into the body to affect those organs?