The line the unions should be taking in my opinion is this:
Baggage handlers, caterers and cleaners are not subject to this screening and thus the possible long term side effects it may cause. It is therefore the case that screening aircrew is an unnecessary potentially harmful procedure that in actual fact does not render airside "sterile" at all.
Jokes aside I fear this is actually quite a serious matter. I know we will hear from some expert that argues that its in no way harmful. How many times have these "experts" over time been proven wrong. Mobile phones, asbestos and who knows what else.
I think i'd be very slightly more comfortable if the screening of aircrew did in actual fact render airside totally sterile. The reality however is that its a staged populist policy so the travelling public think that its totally safe to travel by air.
If its no good for pregnant aircrew its no good for any aircrew.