Saturday, 14 July 2012

Bisphenol A in Plastic - A Hormone Mimic and Endocrine Disruptor

Reports of the potentially harmful effects of Bisphenol A continue to appear. Bisphenol A, or BPA, is a chemical used to make hard plastics and is present in the final products, which include polycarbonate water bottles and the epoxy resins that line aluminum cans. It mimics the action of estrogen, a female hormone. The network of hormones in humans is referred to as the endocrine system, so BPA is said to be an endocrine disruptor. The chemical is present in the bodies of more than ninety percent of the United States population.

Mixed beans from containers that don't contain BPA: photo by Lynne C
Polycarbonate is a hard and clear material that is used to make products such as the lenses of eyeglasses, water bottles, baby bottles, sports equipment and sealants for dental fillings. These can all contain BPA. An epoxy resin containing BPA is added to the interior of food and drink cans to protect consumers from the aluminum in the can, which can also be a toxic substance. In addition, BPA is present in the coating of nearly all cash register receipts and has been found to contaminate paper money around the world.

Bisphenol A is controversial substance. The official stance of most governments is that the concentration of BPA in the environment is too low to hurt humans, with the possible exception of babies and a developing fetus. However, scientists are continuing to find evidence which suggests that it can be dangerous. A lot of the research has been done on mice, but some observations have been made by studying humans.

Special precautions are needed for babies because their bodies are so small, which means that a specific amount of BPA will be more concentrated in their bodies than in an adult’s body. In addition, the way that their food is prepared encourages the buildup of BPA. When a plastic bottle containing BPA is heated to warm up baby formula or milk, the chemical escapes into the liquid in the bottle at an increased rate. In addition, the lining in cans of infant formula may contain BPA. Some research suggests that BPA is most likely to be harmful during fetal development.

Recent reports of scientific research concerning the relationship between BPA and human and animal health can be found at the Science Daily website, which gathers press reports and other publications from universities and research organizations.

The evidence that BPA is dangerous is very compelling, although not conclusive. For example, after a ten year study, researchers found that healthy people who had a higher concentration of BPA in their urine were more likely to develop heart disease. Pregnant women with a higher concentration of BPA in their urine at the sixteen week stage of pregnancy were more likely to have babies who wheezed when they breathed. Mice exposed to BPA while pregnant had babies born with mammary gland changes that predisposed them to cancer. Even more worrying, the same observation has recently been made in monkeys, which are primates, just like us. BPA has been implicated in the development of other types of cancer too. Research has suggested that BPA also plays a role in creating behavior and fertility problems and in the development of obesity.

Recently yet another harmful effect of bisphenol A and its hormone-mimicking property has been reported. The chemical has been found to promote the mating of fish from different species.

There is so much research about the potentially damaging effects of bisphenol A that it seems prudent to me to reduce the amount of BPA entering our bodies as much as possible. For example, I do eat canned beans, but I make sure that all the beans that I buy are packed in cans without a lining containing BPA. You can check the website of your favorite bean companies to see if their cans contain BPA. Cans of organic beans are most likely to be BPA free. I also check the label on any plastic container that I plan to buy to make sure that the product is free of BPA. If I were pregnant or had a young baby to care for I would be especially careful to use BPA-free products. Health Canada, which is part of the Canadian government, has information about keeping BPA away from babies.