It's a very good point and I'm glad the parent raised it. But wouldn't you find it distressing if teenagers were regularly found with a teaspoon full of plastic in their stomachs?
We regularly find teenagers smoke behind the school (at least around here), we don't panic because of it.
There is a laxative product that is commonly prescribed to childhood cancer patients that is just polyethylene glycol. You take about a teaspoon of plastic micropellets and stir them up in a glass of water and drink it.
The PEG used for medicine has very short chain lengths, and I would be surprised if it isn't liquid or water-soluble, and not taken in the form of actual micropellets.
I think we'd be a bit more disturbed if teenagers accidentally ingested the teaspoon full of plastic whilst going about their daily lives and eating their regular diet, especially if the plastic wasn't designed in a way which made it easily pass through the gut.
That would say more about the teenagers than about usage of plastic in the modern world.
>Agreed, it seemed a trivial quantity for such a large animal.
Go swallow 6 grams of plastic. Let me know how that works out for you.
To add to your point, a plastic grocery bag weighs in under 6 grams. I don't want that in my body.