The health effects of a radar system in Europe are ok in my opinion. They are tolerable as long is it is not imposing on any ones right based on where it is located. Every country has the right to defend itself, and Europe is just building a defense system in case an unforsee war would ever break out.
Although exposure to such a system could cause cancer it is incredibly unlikely that the population would be exposed to the radiation produced by the system. It should also be noted that this system will prevent a even larger threat to the well being of the population in times of war.