Not sure we can conclude much there tbh, their own numbers and the numbers in other studies they mention show truly enormous ranges for their rather small sample sizes. Plus, if they're right and the contamination is mostly coming from cap damage, it'd vary immensely by the kind (and treatment) of the cap and luck on how much damage it got, and not the kind of bottle, even if they do currently correlate.

So a useful study to say "stop painting the insides of caps, duh" but it hardly seems like anything intrinsic to the container. And hard to extrapolate to other areas which may not paint their caps, or anything that uses corks.

I don't think they're painting the insides, it sounds like the bottling machine has a hopper full of caps, and they rattle around in production and chip microscopic bits of paint off and those stick to the insides and everywhere, until washed off by the booze.

Ah, yep, you're correct - I was misinterpreting the pictures in the paper. On rereading, they seem pretty clear about it being paint on the outside that somehow gets on the inner surface.

Though also:

>The results show that glass containers were more contaminated than other packaging for all beverages except wine, because wine bottles were closed with cork stoppers rather than metal caps.

So yeah. Cap differences, probably for fashion more than function, which are probably easily remedied.