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Sunday, February 22nd, 2004

safety of reusing plastic bottles

Last week I wrote about re-using plastic bottles to reduce landfill waste. My friend Bruce pointed out the controversy about safety issues: some people claim PET plastic was not designed to withstand repeated use, and begins to break down, releasing toxins.

Clearly that’s a bad thing. I don’t need toxins in my water; I get enough of them in my salad.

A moment’s research located the controversy. But as I dug deeper, I found solid conclusions, backed up by independent lab analysis.

The mutant-baby predictions started with a research paper by a U. of Idaho student on the subject of contamination caused by PET plastic bottles. It claimed, “Four compounds, 1,4-benzenedicarboxaldehyde, benzoic acid butyl ester, 4-ethoxy-benzoic acid ethyl ester, di(2-ethylhexyl) adipate (DEHA), were found to migrate from PET bottles exposed to conditions of reuse.”

News of this paper circulated widely, fueled by “sky is falling” emails, like the one about buying a drink for a pretty girl and then waking up the next morning in a tub of ice with a note reading “call 911; we’ve just taken both your kidneys” tacked to the wall. And I think the PET/DEHA chain email held about as much truth.

The American Plastics Council published a refutation of the U. of Idaho paper, noting conclusively that “DEHA is not inherent in PET as a raw material, byproduct or decomposition product.”

But if DEHA isn’t used in making PET plastic, how did the U. of Idaho student’s analysis find traces of it in the water? According to a hoax-busting page put up by the Cooperative Research Centre for Water Quality and Treatment in Australia, “the concentrations of plasticisers detected in test bottles in [a] Swiss study were the same as those in blank water samples which had not been in contact with PET.” In other words, the U. of Idaho student hadn’t found contamination; he’d found statistical noise.

What about the other toxins identified in the original thesis? Although not addressed specifically by any of the official-sounding refutations online, they’re covered in a document from the Plastics Council entitled, The Safety of Polyethylene Terephthalate [PDF]. This paper presents a readable 2-page summary of the issue, and quotes a study by the International Life Sciences Institute that concludes,

“PET itself is biologically inert if ingested, is dermally safe during handling and is not a hazard if inhaled. No evidence of toxicity has been detected in feeding studies using animals.”

The only risk of PET bottle reuse that any of these websites admit to is bacterial infection due to poor hygiene. In other words, if you don’t wash your plastic beverage bottles, they’ll become host to potentially dangerous populations of bacteria.

The Plastics Council PDF on PET safety distinguishes PET beverage bottles from microwavable food trays — as the latter are intended for one-time use only, and are labelled as such. The implication is that reuse of beverage bottles is perfectly safe. The Plastics Council stops short of approving such reuse, but remember that they have a financial interest in the issue. The PDF quotes a second study from ILSI on the topic of “Refillable Plastic Packaging,” which states,

“… the levels of migrants potentially present in beverages packaged in PET bottles are below applicable international extraction limits that are based on safety considerations and orders of magnitude lower than levels causing adverse effects in toxicity studies. The use by consumers of PET polymer in food packaging, therefore, is demonstrated and considered safe.”

I don’t know what reuse conditions the ILSI tested, but it’s evident there is no immediate risk to reusing PET beverage bottles. Replacing bottles monthly seems like a sane compromise.

And, after that, the bottles need to be recycled. But you knew that part already.

Update 2007-02-25: Much has been written elsewhere about the scourge of plastic water bottles — e.g. water being shipped 5000 miles from Fiji (!) to California despite the presence of excellent water at the nearest tap — but rather than regurgitate that I’ll just say I bought a couple Klean Kanteens (stainless-steel water bottles) to remove myself from the plastic-bottle industry altogether.


Tags: pet, petplastic, deha
posted to channel: Recycling
updated: 2007-02-25 12:17:58

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