Hi,
Thank you for your query. I can understand your concerns.
Polycarbonate (recycling code of 7 )has been commonly used to make the sturdy reusable water bottles that many of us use.
Polycarbonate is made of a monomer called
bisphenol A (BPA). As the plastic breaks down over time, BPA is released into the water held in polycarbonate bottles, particularly when the bottle is heated (as on exposure to direct sunlight for a number of days as in your case) or repeatedly washed.
Research in animals has found BPA can cause a range of conditions — such as cancer,
diabetes, obesity and reproductive and developmental disorders.
But there's nothing much in the way of identified effects in humans .
The best bottles to use and reuse are those with the recycling codes 2, 4 and 5. 2 and 4 are made from polyethylene and 5 is made from polypropylene.
Check that reusable bottles say they are 'BPA-free',
Regards
Dr. T.K. Biswas M.D.
Mumbai