I'm not sure that any legal different chlorination levels between pools and water parks are making much of a difference in whether or not there is a hygiene and health outcome difference between swimsuits of the short/trunks variety or of the thong/speedo varieties. I am certain that the highest levels of chlorination considered safe in the EU for public pools or water-park use aren't going to kill all disease agents in an average municipal pool even within 24 hours. And it's not like single-piece, breast-covering swimsuits worn by women in French pools are all of lesser cloth area than male swimsuits of the short/trunks variety. In the absence of scientific proof, the public health/hygiene argument for "the rules" restricting swimsuits in pools may come across as nothing but an example rooted in cultural bias bereft of adequate knowledge. For saunas, I've not seen evidence that swimsuits that end up frequently in chlorinated water is any more of a public health and hygiene danger than if the sauna use was restricted to just naked people.

If health/hygiene is the excuse, the excuse is only objective if rooted in science. "Is it?" is a fair question when it comes to sauna use. My expectation is that a high-temp, strongly chemically cleaned towel dried at very high heat levels and stored properly prior to use has lower disease agent levels than what is inside the typical human ear and/or various bare skin parts of the human body.

For those who pay attention to the professional swimming world, more skin covering by advanced fuller-body covering swimsuits are increasingly seen as providing a competitive advantage. Which is why this kind of stuff was restricted: http://www.nytimes.com/2009/07/25/sp...swim.html?_r=0. The health/hygiene argument against those suits would be a joke.