People die cycling so hard pushed to say it's safe full stop, you need to add context
Cycling slowly on a cycle path is more likely to be safe then hurtling down a mountain at high speed
All about context, not always 'safe' as most would understand it
Certainly:
A helmet only functions in te case of an accident, the rest of the time it performs no actual function at all
Lets look at the actual percentage of deaths caused by head injury according to road user group
Pedestrians 34.8%
Two wheeled vehicle 13.1%
Vehicle drivers 28.1%
Vehicle passengers 18.1%
Cyclist 5.9%
Which raises the same old point.........
If helmets prevent these deaths, then why are Headway and the evangelists only looking at their use for the group that represents the lowest fatalities