Imagine if an evil company added toxic chemicals to your water.
Imagine if they had been adding this chemical to your canned food, your food containers, your plumbing, and even your baby bottles for years.
Imagine if your government and regulatory agencies had ignored this problem because they were in cahoots with the chemical industries.
Now that’s a news story.
That’s the story of BPA. Or at least that’s how the story of BPA has largely been portrayed in the media.
Whistle-blowers claim that regulatory agencies are in the pocket of big industry. They claim that governments are resting on their laurels, refusing to take action on obvious research showing BPA is an omnipresent menace to your health.
Big chemical companies are supposedly duping innocent consumers like you by knowingly tainting household products with a toxic, hormone disrupting, cancer-causing synthetic compound called BPA.
Many companies have removed BPA from their products, and the FDA and Health Canada have banned BPA from plastic baby bottles, which only fuels the hysteria. This is despite the fact that both agencies have issued reports stating BPA is safe (here and here), and the fact that companies had already removed BPA from these products before the ban due to consumer demand.
You’re a rational, skeptical, Imprüvr who isn’t easily swayed by media uproar, yet it’s hard not to take notice when every plastic container now brags about being BPA-free.
In this article, you’ll learn what the evidence really says about BPA, and if this fantastic conspiracy is really supported by fantastic evidence (which it would need to be if it were true).
What the Evidence Says About BPA and Your Health
Let’s cut to the chase. There have been over 7,000 studies on BPA since 1960.
To keep things simple, we’re going to focus on the best review on this topic to date, published in 2011.1 It’s gotten almost no coverage, despite being the most comprehensive paper on the safety of BPA. It’s also freely available for your reading pleasure.
The study is titled “Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A,” and was published by the German Society of Toxicology in the Journal of Critical Reviews in Toxicology.
The researchers examined almost every relevant study and previous review on BPA since the early eighties. Here’s what they concluded.
Why BPA Isn’t Bad for You
Early animal studies found that when mice, rats, and dogs were fed BPA, they sometimes developed low organ weights, impaired hormonal function, and infertility. These effects sometimes occurred at doses of BPA that you might be exposed to in daily living.
However, most of the studies suffered from severe methodological issues:
- Small sample size.
- Inadequate randomization (They often used animals from the same litter, which is a no-no).
- Lack of adherence to proper testing standards.
- Poor reporting of methods (Sometimes they didn’t even report the number of animals tested).
- Poor or nonexistent statistical analysis.
These studies were also exploratory, which means the researchers were giving the animals large doses of BPA to cause health problems. This way, they would know what to look for in larger, more standardized studies designed to determine what safe levels of BPA exposure might be for humans.
More recent, higher quality animal studies have found that doses of BPA below the safe upper limit (the tolerable daily intake, or “TDI”) do not cause any negative health effects. In one recent study, doses of over 40, 400, and 4,000 times the estimated exposure in humans caused no health problems in mice.2,3
Most People Don’t Consume Dangerous Levels of BPA
To exceed the tolerable daily intake (TDI), you would need to consume 10,000 times more BPA than most people ingest in a day.
Most adults consume around 0.026 µg (micrograms) per kilogram of bodyweight per day (and some new evidence4 indicates this level is declining). The TDI is 50 µg/kg/day.
0.026/50 = 0.000052.
In other words, you’re probably ingesting about 52,000% less BPA than the minimum amount considered to be potentially dangerous.
If you weigh 70 kilograms, or 154 pounds, you would need to eat about 513 pounds of canned soup to exceed the TDI. (Table 6 of this review gives a great overview of the amount of BPA in various foods).5
Urine and blood tests have also shown that most people have extremely low levels of BPA. In most cases, the levels are almost the same as the absolute minimum limit of detection of the study methods (which means they’re really, really low).
BPA is Rapidly Detoxified by Your Body
When humans consume BPA — in controlled or free-living conditions — virtually all of it is rendered chemically inactive by the liver. After BPA has been absorbed and processed by the liver, the amount left in the blood is extremely small, and only about 0.2% is still active. When monkeys are fed BPA, about 70% of it is inactivated five minutes later.
Based on how fast it appears in the urine, researchers estimate that BPA stays in the body for at most 1-2 hours. There is also some evidence to suggest that it may be much shorter than that.
Most of the studies that suggest BPA may be dangerous injected animals with BPA. This bypasses their detoxification pathways, which may amplify the negative effects. Several lines of evidence also suggest that mice and rats may be more sensitive to BPA than humans.
Even Pregnant Women, Babies, and Old People are Safe
There is no evidence that pregnant mothers or their fetuses are more susceptible to the effects of BPA. Virtually no BPA reaches the fetus, and the small amount that does is almost completely inactivated.
The maximum estimated amount of BPA that’s leached out of plastic baby bottles is still well below the safe upper limit.
There is also no evidence that old people are less able to detoxify BPA.
However, not everyone is off the hook.
Why Sick Babies and Factory Workers May Need to Worry About BPA
If you have a baby in an intensive care unit (ICU), they may be exposed to BPA levels above the safe upper limit.
One study found that newborn babies who received intravenous injections in the ICU consumed about twice the maximum recommended safe intake of BPA. The bags and medical tubing used to infuse the I.V. fluid are lined with BPA, and it’s also used in some other medical devices.
However, there’s little reason to believe BPA harmed these kids. The tolerable daily intake, or TDI, is the safe upper limit that you could theoretically consume for your entire life. The babies weren’t in the ICU for long, which means they only consumed excessive BPA levels for a few days — not their entire lives.
In this case, you would also have to weigh the small risks from BPA exposure against the larger risks of whatever put them in the ICU.
One study also found that industrial paint workers may exceed the upper safe level of BPA, though other studies have not found this to be the case. It’s still not clear what steps could reduce their risk, but it seems likely that more protective clothing and/or respirators may help.
BPA Is Probably Not Dangerous, but Poor Reporting Is
BPA is hot news.
Everything you put in your body has some potential to be harmful. At present, however, the vast majority of evidence indicates that BPA is not harmful, or even biologically relevant to any significant degree.
BPA is rapidly converted to a harmless, inactive form minutes after entering your body. It’s also eliminated in your urine after about 1-2 hours. Most people would need to consume thousands of times more BPA than they already do to exceed the safe upper limits.
It’s important to do everything you can to stay healthy.
It’s important to stay informed.
It’s important to avoid potentially dangerous chemicals that could give you cancer, heart disease, diabetes, hormonal imbalances, or a second head.
Luckily, BPA doesn’t do any of those things.
It looks like your plastic water bottle is probably not going to give you man boobs.
1. Hengstler JG, Foth H, Gebel T, et al. Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A. Crit Rev Toxicol. 2011;41(4):263–291. doi:10.3109/10408444.2011.558487. Abstract: http://pmid.us/21438738 | Full Text: http://goo.gl/AlSti
2. Ryan BC, Hotchkiss AK, Crofton KM, et al. In utero and lactational exposure to bisphenol A, in contrast to ethinyl estradiol, does not alter sexually dimorphic behavior, puberty, fertility, and anatomy of female LE rats. Toxicol Sci. 2010;114(1):133–148. doi:10.1093/toxsci/kfp266. Abstract: http://pmid.us/19864446 | Full Text: http://goo.gl/C86Ah
3. Sharpe RM. Is it time to end concerns over the estrogenic effects of bisphenol A? Toxicol Sci. 2010;114(1):1–4. doi:10.1093/toxsci/kfp299. Abstract: http://pmid.us/20147444 | Full Text: http://goo.gl/Ki1VW
4. Wells EM, Jackson LW, Koontz MB. Decline in urinary bisphenol a concentrations in the United States. Epidemiology. 2013;24(1):167–168. Abstract: http://pmid.us/23232617 | Full Text: NA
5. Chapin RE, Adams J, Boekelheide K, et al. NTP-CERHR expert panel report on the reproductive and developmental toxicity of bisphenol A. Birth Defects Res B Dev Reprod Toxicol. 2008;83(3):157–395. doi:10.1002/bdrb.20147. Abstract: http://pmid.us/18613034 | Full Text: http://goo.gl/bRzkN