bremnet said:

Howdy - sorry for the delay, was traveling on business. The issue you are referring to below with regards to reusable water bottles is I believe related to the type of liner (thin coating of polymer based material that is coated on the inside of some but not all of these bottles). In most cases when polymers come in contact with food (incl. water) the concerns are usually not in the polymer itself, but in some of the additives (processing aids, plasticizers, anti-oxidants, UV stabilizers, pigments etc) that in some cases have negative impacts on some human metabolic processes. I would emphasize 'some'. The recent outrage over BPA is not supported unequivocally by scientific evidence, but there is enough uncertainty to move away from it as a plasticizer in PET bottles. If one was to use a food grade polyethylene or polypropylene water bottle, requiring no liner, and totally suitable as a water bottle, then there is no concern at all with the long term use of this material in water bottles. Next time you go through the grocery store, have a look at all the packaging - films on processed meets, stretch wrap on fresh meat cuts, all of your cold dairy products - the vast majority of these are made from one of either polyethylene or polypropylene, with a smattering of polystyrene and polyvinylidene chloride thrown in. All perfectly safe.

As for how the balls are made - these are blow molded. If you have a look at the plastic baseballs made for kids that come with a big fat plastic bat (or really any hard plastic ball that you might find at Wal Mart or Toys'R'Us, you'll see the small ridge that runs equatorially around the circumference of the ball (that's the parting line where the two mold halves come together) and somewhere on that line there will be either a little tiny hole or a small protruding knob that used to be the parison where the air was injected into the small plastic glob forcing it to the walls of the mold like an expanding balloon. This is the same type of molding that makes your liquid dishwashing detergent bottle, plastic ketchup and mustard containers, and plastic milk jugs. Hope this helps a bit. cheers