Of all the things you should or could be concerned about, the radiation from your WiFi transmitter is near the bottom of list. There are literally thousands of things that verifiably have a much larger potential to impact your health.
To start with, you should be much more concerned about your diet, the amount of exercise you get, the kind of health care you receive. I'd even be more concerned about the kind of dyes in my clothing, the kind of plastics used in my home, and how slippery my bathroom floor is than about my exposure to minute quantities of non-ionizing EM radiation from my WiFi transmitter.