No. There is no evidence to support the claim that warming or freezing plastic bottled water releases chemicals that will cause breast cancer.
It is true that if a plastic bottle is exposed to extremely high temperatures, chemicals in the plastic are released into the water inside. But the amount released would still be within normal safety limits and would not cause any harm.
The US Food and Drug Administration (FDA) and the UK Food Standards Agency regulate the safety of all plastic bottled water. Both organisations have reviewed the data on the safety of plastics used in water bottles and concluded that they pose no significant risk to human health.
Content last reviewed March 2012; next planned review 2014