What is BPA?
Bisphenol A, or BPA, is a synthetic chemical used mainly in plastics and resins. It was first synthesized in 1891, and is made through the condensation of acetone and phenol. It was not used commercially until the early 1950's, when chemists discovered it was useful in making epoxy resins. These resins are used as protective coatings to line products like food cans. A few years later chemists found a way to obtain a higher grade, more pure BPA product, which could be made into a durable plastic called polycarbonate. Polycarbonate found use in electronics, car manufacturing, food and drink containers, CDs and DVDs, and a slew of other applications that called for a hard, clear plastic. More recently BPA has been used in products like dental sealants, orthodontic hardware, and thermal paper such as that used in retail receipts.
Basically anywhere you look you will find BPA. It is such a versatile product it has found its way into a large majority of the things we use on a daily basis. It is manufactured in huge amounts. The US had produced half a billion pounds by the late seventies, and global production is presently over six billion pounds per year. That makes it one of the top 50 products produced globally by the chemical industry.
What's wrong with BPA?
We have established that BPA is a very useful product, and since it has become so plentiful, it makes sense for the public to be aware of any hazards it may convey. It has been known sine the 1930's that BPA has estrogen mimicking properties. It has also been known for years that BPA can leech out of the products that contain it, especially when it is heated. Scientists at Stanford who were doing research involving estrogen discovered this when their results were repeatedly skewed by BPA leeching from flasks that were heated in their experimental methods.
How Does BPA Affect The Body?
Simply put, the human endocrine system is made up of glands that produce hormones. Hormones are chemical messengers that are stored in glands and released into the blood under certain conditions. Once released they find their target tissues via a receptor mechanism, much like a lock and key, and they relay a message. For example, vasopressin is a hormone that is stored in the pituitary gland. When the body becomes dehydrated, vasopressin is released into the blood, where it travels to the kidney and signals it to retain water. It has been well established through years of experimentation that BPA has an effect on the human endocrine system. It exerts it's effect by mimicking hormones that the body naturally produces(such as estrogen), effectively tricking tissues in the body into believing some hormone levels are higher than they actually are.
So how strong is this effect and does it cause enough disruption in the body to be of concern? This is where things become tricky. Much research has been done. But much of the research has been funded by either the chemical companies themselves, or other companies that stand to make a profit from the sale of BPA. Here is a quote from an article called "The Politics of Plastics", featured in the American Journal of Public Health, in November 2009.
Most alarmingly, they highlighted an apparent funding effect in the BPA research. Between 1997 and 2005, there were 115 studies on the effects of BPA at or below the safety standard, conducted by dozens of laboratories in the United States, Japan, and Europe. The reported effects of BPA included changes in fetal prostate and mammary gland development, disruption of chromosomal alignment in developing eggs in females, altered immune function, metabolic abnormalities, and changes in the brain and behavior. Of these 115 studies, 90% of those that were government funded reported some effects from exposures at or below the reference dose, whereas none of the 11 studies funded by (the chemical) industry reported any effects.
This kind of thing makes me skeptical, along with the fact that the two major studies that the government has used to determine safe levels of BPA were both funded by the American Plastics Council, and the Society of the Plastics Industry (according to the same journal article as above).
After I spent a couple days reviewing journals and trying to find reputable sources online here is what I believe to be the heart of the issue.
There is definitely evidence to show that BPA has endocrine disrupting capability in humans, and that BPA is leeched out of products containing it, often into our food. The extent to which BPA is harmful is up for debate, and there are widely differing views. BPA seems to have the most substantial effect during critical developmental periods in the human life cycle. During developmental times such as fetal growth, early postnatal development, puberty, and pregnancy, the body is dependent on hormones to help direct critical processes. At these times we are particularly susceptible to the deleterious effects of endocrine disrupting chemicals. That said I think the best approach, at least for me, is to limit exposure where possible without becoming a freakazoid about it. Here are some useful ways to limit BPA exposure.
If you have to have a reuseable plastic bottle, Look for BPA-free labels. Alternatively stainless steel is lighter than glass and safer than plastic.
Use glass as much as possible at home.
Avoid canned foods (especially tomatoes) when there are easy alternatives like fresh or frozen.
Acidity in the tomatoes greatly increases leeching from can liners.
Do your best to buy BPA free products for babies, such as bottles (which frequently are heated), plastic toys (which are often put in the mouth), or pacifiers (which are very often put in the mouth).
Try not to frequently use products labeled as plastic #7, which are usually hard and clear. I checked the water cooler at work we all use and yep, it was.
Plastic number 1 is BPA free, though I still recommend drastically reducing consumption from these bottles too, there are other chemicals in plastics that can leech out as well. Which I will try to cover in a future post.
I suppose that's all for now, please leave a comment if there is anything you would like to add !
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