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.
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 ??g (micrograms) per kilogram of bodyweight per day (and some new evidence4 indicates this level is declining). The TDI is 50 ??g/kg/day.
Like every other substance you put in your body, the dose makes the poison. When it comes to BPA, most people don???t consume anywhere close to a harmful dose.
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.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3135059/ Critical evaluation of key evidence on the human health hazards of exposure to bisphenol A
asked byAgingHippie (614)
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on May 01, 2013
at 12:17 PM
In fact, I'm increasingly weary of added chemical exposure and increasingly seeing the value in "non-essential" nutrition via plant compounds and gut bacteria by-products.
Recently attended a lecture, on what we can learn from bacteria. The lecturer was studying the interactions between bacteria and other lifeforms: specifically talking about between an algae and bacteria as well as simple jellyfish-like organism and bacteria. What was interesting in these talks is, of course, how these organisms interact with each other. It was a chemistry talk so ultimately he discussed the exact molecule in question that caused various responses. It was not the molecules themselves that were so interesting, but rather the concentration in which these molecules acted. One such molecule had an effect in the ballpark of a mere 60000 molecules per liter of water, which is a tiny amount considering a liter of water contains approximately 3.3*10^25 molecules (hard for non-chemists to imagine that number really).
Of course, there's a big difference between these proto-jellyfish and humans. But if such a simple system is affected by a multitude of outside biological factors, humans are going to be affected by orders of magnitude more, based on an argument of complexity alone.
Humans may be ingesting a seemingly tiny amount of BPA daily, but it's still roughly 1 million times the amount that causes physiological responses in these microorganisms. It is on the order of our own endogenous hormones, which is problematic when these compounds have hormone-like bioactivity.
So, lesson learned: eat your plants, there's tons of small molecules in there that likely have some positive effect on health, and even if they don't, you're ultimately feeding your gut bacteria which produce even more possibly beneficial small molecules. Our environmental exposure is likely causing all sorts of minute effects, minimize non-natural compound exposure.