Subject: What secondary radiation does polyethelene produce from cosmic rays?

We are taking a physics course and we were told that polyethelene was a good way 
to shield a person from exposure to cosmic rays and other particles present in a 
low earth orbit.  This material is being used to help shield the astronauts on 
board the International Space Station.  However, this material we were 
told cannot be used to  shield electronics becasue of the radiation due 
to secondary particle production.  If it cannot be used for electronics then why
 can it be used for humans.  If the secondary particles are harmful to 
electronics then it seems to me that they would also be harmful to humans.

Re: What secondary radiation does polyethelene produce from cosmic rays?