The theory of carcenogenic particles leaching into water in a re-filled bottle made of plastic is one of the modern hoaxes. The particluar chemical claimed to be present isn't even used in the manufacture of the bottle.
Lots of info on plastics from US site:
here from the American Chemicals Council plastics info site.
What may cause a problem is the habit of not cleaning the bottle - every time you swig from the neck of the bottle you add bacteria to the contents, so by the time you've had a few days worth of drinks and re-filling - in the hot weather.....you're enjoying a thin bacteria soup.........