Thirty years of use and demonstrable, well-documented lack of increased cancer rates in the users. That's why it's irresponsible to use them for political reasons. Or are you among those people who think they make you more secure?

I would be less worried about proving them safe ex ante than maintaining the safety of those around them. Regular monitoring for leakage and exposure would be a great start. The reason gate agents are not allowed to wear monitors is political. If there is any problem found I think it that workplace rule should be considered malicious.