A study published last week in the journal PLOS ONE has brought new attention to the chemical bisphenol-A (BPA) as a potential obesogen – substance that causes obesity – in humans.
Out of 1,326 school-age children in China, girls between ages 9 and 12 with higher than average levels of BPA in their urine were twice as likely to be in the top 10th percentile for body weight. Girls with exceptionally high BPA levels were 5 times as likely to be obese. While the association was not found in older girls or school age boys, it did hold up after controlling for other factors commonly associated with obesity like diet, exercise and parental body weight.
BPA is a synthetic compound used in water bottles, food containers, consumer plastics, thermal paper sales receipts, food and beverage can linings and the lining of water pipes. With a structure similar to estrogen, it has shown hormone-like properties that have won it a stream of bad press in recent years. In 2010 Canada declared it a toxic substance for humans. The US has banned its use in baby bottles and many product manufacturers have followed suit, manufacturing and marketing all consumer products as BPA-free. It’s almost difficult to find a reusable water bottle that is NOT BPA-free at this point.
As with most studies on potential human toxins, we want to take the message and run with it… “BPA causes obesity!” Unfortunately, and also like most studies on toxins, that’s NOT the proper conclusion here. Because the study looked at already obese kids, we cannot know for sure that the BPA caused their obesity. Study authors note compelling alternative explanations. Extra body fat provides more storage space for higher levels of BPA in the body. Obese children may eat more unhealthy packaged and processed foods that likely contain more BPA. Is it the food or the BPA?
So what CAN we take away? The evidence is compelling and growing stronger that BPA is an environmental toxin to be avoided. So by all means, “BPA-free” is better than “BPA-full.” But we must fight our inclination to let news about an individual toxin distract us from the strongest obesogens to ourselves and our children – poor diet and physical inactivity! Because a BPA-free bottle full of water will always be healthier than one full of soda.