It is illegal to work more than 48 hours in Europe at the moment,
Britain (my home country) has an opt out of this. As the EU is
reducing the amount of laws that it sets down it feels that it is
important that the laws it does legislate apply to the whole of
Europe, hence we are loosing this opt out.
The arguments are based on health and safety.
One argument is that people who work more than 48 hours are more
prone to heart attacks and stress related injuries.
It seems in line with Szasz's philosophy to say that it is my choice
whether I expose myself to those risks.

A slightly different argument would be concerning, for example,
truck drivers. When they work longer hours they become a bigger risk
to other people on the road, do you think this argument holds water.

Is it there choice to take the risk that they might kill someone and
be subject to the consequences of the law if they do so kill someone?

Just as we cannot lock up paedophiles longer than their jail
sentence on the basis that on release they have a higher chance off
re-offending. Ie just because an action/life style has a chance of
hurting someone, we cannot do anything until someone is hurt.