Wi-fi homeworking - health hazard?

I've just gone wireless in my shed/garden office and have been childishly excited about the prospect of teleworking from my sofa (and a friend of mine tells me her husband has taken to working wirelessly from the toilet instead of taking the newspaper in with him). So far it's worked marvellously well (I'm on a BT Home Hub network) but another friend raised the question this morning of possible wi-fi health hazards. The issue was covered briefly earlier this week in The Times and there's a nice round-up piece with links to other articles at Wi-Fi Networking News.