Safety issues with polycarbonate plastic bottles?

March 2, 2007 1:27 PM

I'm concerned about the reports of polycarbonate baby bottles being unsafe (I read about it here). We use one of the brands that was tested -- is there more information out there about this possible problem? Any chemists care to comment on the legitimacy of the study?
posted by _sirmissalot_ to health & fitness (11 comments total)

Such a synchronous world! My wife and I were discussing this not 2 hours ago.
And 1 hour ago I threw out our 6 Playtex bottles and bought new ones ("Nuby" from Target; offbrand, cheap, durable--- I bought new nipples however because the inverted ones with the Nubys are wonky) and feel better.
Overly cautious.
Yep.
Relaxed dad?
Priceless.
posted by Dizzy at 1:38 PM on March 2, 2007

Previously, on water bottles and bisphenol A
posted by clavicle at 1:39 PM on March 2, 2007

Thanks for that link. However, it seems that maybe baby bottles are a different story because of the frequent contact with very hot water through dishwashing and/or sterilization.

(I also believe that question should have been tagged more clearly--I looked through every post tagged "bottle," for instance.)
posted by _sirmissalot_ at 1:52 PM on March 2, 2007

And 1 hour ago I threw out our 6 Playtex bottles and bought new ones ("Nuby" from Target; offbrand, cheap, durable--- I bought new nipples however because the inverted ones with the Nubys are wonky) and feel better.

Not to be snarky, but why are the "Nuby" bottles better? Are they not made of polycarbonate? I searched the web and couldn't find any info.
posted by Big_B at 2:00 PM on March 2, 2007

Well from two stories:

1 - "As for polycarbonate bottles, Health Canada says: -while tests have shown that some unreacted bisphenol A can migrate to water over time, all scientific evidence suggests that this leaching effect is so small (few parts per billion range) that consumer exposure to bisphenol A from this source is well below levels that could cause harm to human health."

2 - "Health Canada says while some suspect the chemical may cause harm to the human hormone system, its studies have shown that bisphenol A is almost completely consumed during the manufacturing process.

"The federal agency says that its tests on plastic baby feeding bottles and other plastic products showed the presence of small residual levels, which could only leach into a beverage under extreme conditions."

Frankly, plastics contain chemicals. Lots of them. You drink from a different plastic, it will have different chemicals in it. In high doses, probably lots of these chemicals are bad for us. But the basic rule of toxicology is that the dose makes the poison - at low doses, a lot of substances that at high doses are harmful are not harmful at all. Their harm is not proportionately reduced; it's eliminated altogether.

Sometimes government agencies are too cautious in their findings. On the other hand, environmental groups like nothing more than to declare artificial things hazardous. It seems that on the evidence, you have nothing to worry about. Your kid is going to injest more harmful substances just breathing the air. But it's your money. Just don't imagine that the alternatives are necessarily perfect.
posted by Dasein at 2:42 PM on March 2, 2007

In this study, (1) change in the concentration of bisphenol A (BPA) leached from polycarbonate (PC) tube to control water (BPA free), seawater and river water at 20 and 37 °C as a function of time ... The BPA leaching velocity in seawater was the fastest in three samples (11 ng/day for seawater, 4.8 ng/day for river water 0.8 ng/day for control water at 37 °C).

the rate at which the bisphenol-A clearly depends on what else is in the water, as stated in the abstract: the presence of ionic species and pH changes can increase the bisphenol leaching rate by a factor of 5 or so. so it's going to depend on what, exactly, you put in the bottle.

but even if you assume a factor of 20 increase due to the acidity of your milk or formula or wahtever, that is still something on the order of nanograms. nanograms per day that your water is sitting in the bottle.

that's a fantastically small amount.

consider by comparison the research discussed in the wikipedia article:

Research ... describes exposure of pregnant rats to bisphenol A at 2.5 to 1,000 µg per kg of body weight per day. At the equivalent of puberty for the pups (50 days old), about 25% of their mammary ducts had precancerous lesions, some three to four times higher than unexposed controls.

that's 1mg, per day, per kg of body weight, which increased the breast cancer incidence by a factor of 3-4. about 10,000 times more dose than the worst-case scenario i've assumed of a 20x increase in BPA leaching rate.

i don't know. bisphenol-A is not the only toxic component of polycarbonate, nor is there only one kind of polycarbonate - it's a broad category of polymers, and each has different chemistries. so YMMV. but to me, it sounds like the usual sort of public-health tempest in a teapot.
posted by sergeant sandwich at 4:13 PM on March 2, 2007

that is, 10k times more dose assuming you have a 2-pound baby!
posted by sergeant sandwich at 4:16 PM on March 2, 2007

OK, mea culpa, i didn't read very well: the research cited by wikipedia found the 3-4x increase in rat cancer at the lowest dose, which was 2.5 micrograms/kg/day. that is still quite a bit more than the measured leaching rates, though not as much.

i didn't want to misrepresent anything here, but i still think it's being made into a bigger deal than it really is. you'd have to leave warm water in your baby bottle for months-years to approach the amounts we're talking about here.
posted by sergeant sandwich at 4:31 PM on March 2, 2007

Well, I used to be a chemist, sort of, and I know all about this (I've been tracking info on hormone-mimicking plastic additives for years) and I didn't (and don't) worry about it. These chemical are so generally ubiquitous that I consider it pointless to worry about a particular vector.
posted by nanojath at 10:16 PM on March 2, 2007

But the basic rule of toxicology is that the dose makes the poison - at low doses, a lot of substances that at high doses are harmful are not harmful at all. Their harm is not proportionately reduced; it's eliminated altogether.

This principle has strong intrinsic plausibility, but it should never become an article of faith; as such, it has a long history of misuse, especially in the nuclear industry, where it has gone under the name of the threshold effect.

I think there is some danger of that here, as well. A tiny amount of a toxic chemical can only produce a tiny injury directly, but many cancers do arise from single cells (they are clones) which have been damaged in a particular way-- in other words, they are the result of a very tiny injury.

That basic principle of toxicology also fails to take into account the nature of the immune system, which is designed to detect and respond to infintesimal amounts of foreign material (antigens) before they can multiply into larger amounts, as bacteria and viruses do, for example. If your baby develops an immune reaction to something which has leached into its milk, and do keep in mind that one function of milk is to program the baby's immune system, and that leached chemical resembles a hormone, that is not likely to be entirely inconsequential, and those consequences may not become apparent until years later.
posted by jamjam at 10:50 AM on March 3, 2007

@Big_B: Although I can't speak to what Target carries, it looks like Nûby does at least have a Polypropylene Line.
posted by gpen at 9:55 PM on March 10, 2007