Don't know if someone has said this before, sorry if it's been covered.
In Year 10 (2years ago) I actually did a major assessment on the helmet laws, I covered a variety of different arguments on the topic, both for and against and I actually uncovered some pretty scary stuff.
Apparently, and yes, there is statistics that support this, an incident on a bicycle that involves a head hitting the pavement can actually cause a serious head trama known as Diffuse axonal injury (DAI) due to the increase in torsional forces as the distance between spine and scalp is increased by the helmet shell.
A study conducted in 2003 suggested the above, also indicating the effectiveness of fullface helmets is infact inferior to standard helmets in preventing the above.
Follow this
link to read the relivant pages of the report
''It has been suggested that the major causes of permanent intellectual disablement and death after head injury may be torsional forces leading to diffuse axonal injury (DAI), a form of injury which usual helmets cannot mitigate and may make worse''
DAI is a serious condition and statistics have shown that 3 / 4 bicycle incident hospital admissions are dignosed with DAI. DAI is a major cause of unconsciousness and persistant vegitative state, often leading to coma, 90% of DAI patients never regain consciousness.
Along with the above I incovered information relating to the alternative attitudes drivers have toward cyclists with and without helmets.
In a UK study it was found that helmet clad cyclists are given a very small berth when passed by cars, 8.5cm on average as drives see them as 'experienced'. In comparrison, cyclists not wearing helmets were given on average a 1.2-1.3m berth when being passed as drivers saw them as 'inexperienced'.
''The relationship between rider position and overtaking proximity was the opposite to that generally believed, such that the further the rider was from the edge of the road, the closer vehicles passed. Additionally, wearing a bicycle helmet led to traffic getting significantly closer when overtaking. Professional drivers of large vehicles were particularly likely to leave narrow safety margins. Finally, when the (male) experimenter wore a long wig, so that he appeared female from behind, drivers left more space when passing. Overall, the results demonstrate that motorists exhibit behavioural sensitivity to aspects of a bicyclist's appearance during an encounter. In the light of previous research on drivers' attitudes to bicyclists, we suggest drivers approaching a bicyclist use physical appearance to judge the specific likelihood of the rider behaving predictably and alter their overtaking accordingly.''
Abstract from 'Drivers overtaking bicyclists: Objective data on the effects of riding position, helmet use, vehicle type and apparent gender. Ian Walker. Accident Analysis & Prevention Volume 39, Issue 2, March 2007'
Just my points to the arguement.
-Josh