Personally, I think it's a myth that 120V is safer than 230V. The reality is that if you manage to directly connect yourself to either system you are at risk of death!
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I agree with paul, American's tend to view 220-240V as being for heavy appliences like stoves and tumble dryers only and thus treat it with some caution. Although I don't think most europeans would mess with a 30A cooker connector either!
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The statistics that I have looked through relating to deaths due to electric shock show that in Ireland and the UK it's not very likely that you'll be shocked / killed by domestic wiring. In fact, it's one of the least likely ways to be killed. Most of the very few electrical accidents that happen in Ireland seem to be caused by people coming into contact with distribution and transmission voltages. (>10kV)
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Correct grounding of class I appliences and the use of adequate RCD / GFCI protection would seem much more important than the line voltage when it comes to shocks.
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When it comes to fires it comes down to regulation and system design. If a system's installed properly and protected correctly against overcurrents it shouldn't catch fire. Regardless of the voltage.
A badly designed 220V system can overload just as spectacularly as a badly designed 110V one!
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On the US vs European systems.
Having experienced US electrical systems over the last few days I can say that I feel a LOT safer using an Irish / British or schuko 230V plug than a US 110V equivilant. Plugs visibly spark, it seems like it's quite possible to touch live pins on many plugs.
I also don't like the extensive use of Zipcord on many appliences including things like microwaves, irons and washing machines!! These cables just look fragile compared with a normal European 3-core double insulated cable.
Northern European fittings, cable and fixtures just seem much more sturdy and safer. (even the old ones!)
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Also, I notice that far fewer US appliences appear to have a ground connection. I've also seen a few cases where the ground pin was bypassed / removed !
