BPA first came in use as a synthetic estrogen in the 1930s. While its use in humans soon died out, (when scientists found safer versions of synthetic estrogen), chemists discovered the chemical’s knack for strengthening plastics, and the rest is history. Soon it was commonly used in a variety of plastic products, and became a part of our everyday lives.
The potentially harmful effects of BPA, like so many other scientific discoveries, was originally stumbled upon by accident. In June of 1993 a paper showed that BPA leaching from plastic labware equipment was throwing off endocrinolology experiments. Then in 1998, Geneticist Patricia Hunt was doing studies on mice reproduction when she started getting some unusual results. After every other possible culprit was explored, she discovered the underlying problem: a janitor had used an abrasive chemical on the floor, and as a result, the mice were exposed to significant levels of BPA. (Hinterthuer, 2008)
Here’s what all the fuss is about: BPA is an endocrine disrupter. It mimics the hormone estrogen in the human body, by latching onto the same cellular sensory molecules that natural estrogens stimulate. It’s also something that is easily absorbed into the body. During the manufacturing process, not all BPA gets locked into chemical bonds with the plastic. The residual that is left over can work itself free, especially if the plastic is heated. This can happen in a dishwasher, a microwave, or even a plastic container such as a water bottle that’s been left in the sun. As a result, this estrogen-like chemical leaches into the foods we eat, the liquids we drink, and is absorbed into our body. The chemical can even be absorbed through the skin by contact with plastic or inhaled in the form of microscopic bits of dust. Hence the 93% to 99% rate of people who test positive for the chemical in their bloodstream. While the kidneys of mature children and adults are able to quickly eliminate the chemical from their bodies, newborns and younger children have a tendency to retain it for longer periods of time. Combine these factors with a rate of constant and continual exposure, and you understand why scientists are worried that BPA may be adversely effecting child development.
A 2007 meta-analysis in the journal Reproductive Toxicology found that 90% of the studies reviewed had concluded BPA is a health risk. The dozen or so that didn’t were all funded by pro-BPA industries. (Hinterthuer, 2008) So on the surface it certainly suggests that plastic manufacturers are trying to skew the evidence to confuse the public. To be fair to both sides, it’s not as though BPA is all evil, either. There is a reason for its use. “Although we are looking for alternatives, they are not readily available, and there is no ‘drop-in’ replacement for these uses,” argues John Rost, chairman of the North American Metal Packaging Alliance, an industry trade group. “Quick changes that have not been evaluated could impact the real safety issue: food poisoning.” (Alonsa-Zaldivar, 2008) BPA is used to make epoxy resins that coat and seal the inside of cans. This prevents leaks and keeps bacteria from contaminating the food inside.
How much BPA is safe?
Among the biggest questions is exactly how much BPA is safe. Some studies have suggested that concentrations of just one part per trillion can stimulate physiological responses, (Hinterthuer, 2008) far below the FDA’s current safety standards. Many scientists complain that the FDA is applying outdated toxicology standards (poisons), rather than endocrinology standards (hormones), which behave a lot differently than traditional toxins. The advisory panel that rebuked the FDA’s findings found that the FDA was too generous, by a factor of at least 10 times or more, when it set the guidelines for acceptable levels. It’s just one of the things that needs to get hashed out regarding this chemical.