Bisphenol A (BPA) – you’ve probably heard of it if you’ve been paying attention – is ubiquitous and nasty:
- It’s one of the most manufactured products in the world
- It shows up it all kinds of food containers (not just the clear water bottles that some manufacturers are promising not to use BPA anymore in)
- It’s absorbable from receipt paper
- And it’s even found in water systems. (Mutant frogs are the real life 3-eyed fish.)
Alarms about it were finally heard in the media in 2008, the governments of the world started to admit that it was nasty in 2010, and some bans on some products were instituted.
So why write about it now? It’s everywhere so either we’re all equally screwed or we’re not, what else is there to do?
As it turns out, there is a lot more that can be done, with regards to BPA specifically and food safety in general. Yes, BPA is everywhere, but there are things you can do to minimize your exposure to it. That will be covered in this post. More generally, what is or isn’t a safety concern? How can we tell which expert to trust? That’s a much larger topic which will have to be covered in several posts, but I will start in this post by showing what I did (and you can too) to gauge scientific consensus about BPA.
I got hip to the dangers of BPA a couple of months before the media started covering it because a guest speaker for our 2008 graduate seminar in genetics was a scientist who had been raising the alarms about BPA for years. The man was so frustrated by the slow pace of progress on this issue that we got an earful during an off-topic lunch before his official science talk. His story went like this:
He was interested in meiosis, the special kind of cell division that yields egg or sperm cells. That’s what he came to talk about, mechanisms in meiosis. Years ago a colleague in the same field was focusing on DNA replication and division during oogenesis, the process by which the eggs are formed. They had a mouse model, things were going well, great data were being collected. Suddenly, they observed many more abnormal eggs than expected. The results had nothing to do with the experimental manipulations they were performing since the DNA abnormalities appeared in both the control and experimental groups.
It took them months to track the problem to a change in detergent used to clean the mouse cages. The new detergent caused BPA in the plastic to leach out of the cages to be absorbed by the mice. BPA turned out to be the culprit. The DNA abnormalities were gone in clean new cages and replicated when the mice were fed BPA directly. Publications from the lab joined the growing body of evidence from other labs around the world that BPA might be a dangerous pollutant.
Scary take-away messages:
- Even if background BPA levels were safe, conditions existed for catastrophic release of high levels of BPA.
- Some reported effects of BPA exposure affected the individuals exposed, this particular incidence showed that BPA damaged the individuals’ grandchildren: Baby girls are born with the ova fully formed, the eggs having developed concurrently with the rest of the fetus. So if BPA had the same effect in humans as in mice, the eggs with abnormal DNA were being damaged while their mother was still just developing inside the eggs’ grandmother.
- That was not the only effect of BPA reported. It’s been known since the 1930’s that BPA was estrogen-like. The first papers I could find that indicated that BPA was just as potent as estrogen physiologically were from the 1980’s. Papers that showed environmental exposure to BPA were uncomfortably close to physiologically relevant levels started to appear a few years later, along with papers showing possible adverse developmental and carcinogenic effects of BPA exposure. The studies mentioned above simply combined one of the more alarming effects with unassailable animal data. Even fence sitters who had been holding out for almost 2 decades were finally convinced.
Back to the story:
While the BPA data continued to be corroborated by other labs, our speaker, among many others, tried to get someone in the regulatory bodies or in the media to pay attention. The narrative arc was depressingly similar to the tobacco story: Plastics manufacturers continued to insist that BPA was only weakly estrogenic, then that BPA levels were still irrelevantly low, then that BPA could not possibly leach out into food, and finally that if BPA was so bad, why haven’t we seen any effects on humans? Never mind that we don’t really want to wait until there were incontrovertible effects on humans. When any major media source paid attention, pressure was applied to kill the story. When he spoke to us, the speaker was especially bitter since a BPA expose he’d been consulting on for a major news show had just been axed.
The good news is that mere months later, the story did break. And 2 years later, BPA was declared a toxic substance and banned by (some) governments from (some) children’s toys and baby bottles. The bad news is that BPA is still everywhere else, and for some effects of BPA it’s already too late to cut BPA exposure after the kids were born.
Final take-away message:
- Your health is in your hands. We’re lucky to have regulations that protect us some, but they are rarely stringent enough and in any case usually come later than necessary. So be pro-active.
What to do about BPA:
- Try to avoid food in plastic containers with the recycle markings 3 or 7.
- If unavoidable, try to avoid contaminating food with degrading plastic. Do not heat plastic containers, with or without food. Dishwashers which combine heat and harsh chemicals are dangerous grounds for plastic food containers, too. Direct sunlight could do a number on plastic polymers unless UV stabilizers were added during the manufacturing process, so avoid direct sunlight. In general stabilizers need to be added for various situations so food containers that are meant to be disposable should not be reused for food; they haven’t been properly stabilized for that use.
- BPA is also found in the waterproof lining for many products including canned food and disposable cups. Again, avoid heat – use coffee mugs instead and ceramic containers for reheating or storing leftovers.
- Try not to handle receipts unnecessarily, and wash hands afterwards – esp. before eating. Scientists trying to figure out why BPA levels in humans were higher than could be accounted for from ingestion noticed that BPA levels were way higher in cashiers and people who regularly handled coated papers for thermal printers.
- Be extra careful if pregnant.
What to do about Substance X which someone said was totally harmful and of which someone else had an equally loud and opposite opinion:
- Disregard anyone who’s claiming a scientific conspiracy. Really, no real scientist would discount a plausible, testable hypothesis that if correct would prove the current consensus wrong because being closer to the truth than everyone else is the path to high impact publications and tenure. A conspiracy claim is usually an admission that all experimental evidence outside of one’s own disproved one’s claims.
- For non conspiracy theorists, wikipedia is a good start.
- Want to double-check wikipedia? Go to Pubmed – what? no trust me, it’s not all impenetrable jargon. If you try to find scientific answers on the Internet, you’ll find all kinds of experts peddling opinions that may or may not be within their area of expertise. And if the experts were not speaking about their specific field, they started out just as ignorant as you and me, so why not see if you can’t educate yourself using the same trusted peer-reviewed resources.
Here’s what I did to get myself up to speed on BPA:
- Went to http://www.ncbi.nlm.nih.gov/pubmed/
- Put in a search for Bisphenol A. The results showed both primary research papers and reviews. The research papers were more or less impenetrable unless you were already active in the research or making a concerted effort to join the field. The reviews attempted to find consensus among the research papers and broadcast that consensus to audiences with various levels of specialization. We wanted to focus only on the reviews, so I clicked on the Review link in the upper right hand corner (highlighted in red below).
- Now I went to the upper left hand and clicked on display settings (highlighted in green above).
- Changed the settings to show Format: Abstract and Sort by: Pub Date. Clicked apply.
- Now I had a long list of relevant review articles, each with a short, hopefully informative summary of the full-length article. Time to read away! The idea here was to gain a qualitative understanding of scientific consensus, so I skipped papers that were irrelevant or focused on minutiae. I paid attention instead to the general conclusions being made and how much debate there were about those conclusions in the past 5 years. With BPA, there was one review suggesting that the new EU regulations were probably adequate, and every other relevant review talking about nasty effects of BPA or how we may be underestimating exposure and not doing enough. Hence the generally alarmist tone of the post.
- Here are some of the reviews I looked through about BPA:
- Hengstler JG, Foth H, Gebel T, Kramer P-J, Lilienblum W, Schweinfurth H, Völkel W, Wollin K-M, Gundert-Remy U. Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A. Crit. Rev. Toxicol 2011 Apr;41(4):263-291.
- Erler C, Novak J. Bisphenol A Exposure: Human Risk and Health Policy. Journal of Pediatric Nursing 2010 Oct;25(5):400-407.
- Groff T. Bisphenol A: invisible pollution. Current Opinion in Pediatrics 2010 Aug;22(4):524-529.
- Keri RA, Ho S-M, Hunt PA, Knudsen KE, Soto AM, Prins GS. An Evaluation of Evidence for the Carcinogenic Activity of Bisphenol A. Reprod Toxicol 2007;24(2):240-252.
- Kang J-H, Kondo F, Katayama Y. Human exposure to bisphenol A. Toxicology 2006 Sep;226(2-3):79-89.
We wanted to start a series of posts on food safety issues because we felt the need for more public discussions that included actual scientific data. Furthermore, we wanted to work out ways to empower you to double check any health related claims seen or heard. We started out with the easy topic of BPA, for which there were more than two decades of data and almost a decade of scientific consensus. Next time we’ll deal with more controversial substances and the finer points of deriving scientific consensus.
Please let us know what you think – what’s working and what isn’t working in our post. We love to hear from you!