Size zero and my Dad

A few weeks ago my dad raised an interesting point. The idea of size zero originally came from the world of the cat-walk model, with designers claiming that clothes look better on ultra thin models. This means that a model needs to diet and exercise to a dangerous extreme to increase their chances of landing a cat-walk modelling job. But doesn't that mean that these people who still design and make clothes intended for size zero models should be sued? Think on it for a moment, after all it is their choices that are forcing these models to put their health at risk for their job, surely that's some sort of infringement of Health and Safety laws?