Many food containers are a source of a controversial chemical known as bisphenol A, or BPA. There has been concern that this agent used in clear hard plastic might be contributing to the obesity epidemic. BPA is an endocrine disruptor because it mimics estrogen in its actions.
Hormonal Effects of Bisphenol A and the Obesity Epidemic:
A study in mice has just shown that this agent may interfere with other important hormones as well. It determined that this could disrupt metabolism. When pregnant or nursing mice were exposed to bisphenol A, their pups did not respond normally to leptin. This hormone signals to the brain when the body does not need any more food. Insensitivity to leptin meant these mice did not know when to stop eating and became obese as adults.
Details of the Study:
The levels of bisphenol A in the mothers’ feed was comparable to those the FDA and HealthCanada permit in human food. Many North Americans have been exposed to this compound, which is used in rigid plastics and the linings of metal cans.
Other pregnant mice were exposed to the synthetic estrogen diethylstilbestrol (DES) as a positive control. Their offspring were even more severely affected. Their leptin response was extremely delayed rather than merely blunted.
The study clarified how BPA disrupts the endocrine system to cause obesity in animals; it is possible that the same mechanisms are at work in humans exposed to this endocrine disruptor.
Where Do You Find BPA?
In the US, manufacturers no longer add bisphenol A to baby bottles as they once did. No one knows, however, whether the substitutes being used are safer.
While BPA is commonly used in the linings of cans, the Campbell Soup company announced a few years ago that it will remove the chemical from its cans by the middle of 2017.
Cash register receipts are an often unexpected source of BPA. If the cashier asks if you want your receipt, you might do well to decline.
Using glass containers for food whenever possible will reduce exposure. It is especially important not to use hard plastic dishes in the microwave or even the dishwasher, as these conditions can lead them to leach BPA more readily.