I've looked a bit, and not been able to find evidence of HDPE getting into cells, or exhibiting biological toxicity, whereas there seems to be quite a bit of ev

I've looked a bit, and not been able to find evidence of HDPE getting into cells, or exhibiting biological toxicity, whereas there seems to be quite a bit of evidence of this for almost every other type of plastic. Still, I wouldn't blame someone for just avoiding all plastic food contact by the precautionary principle. The first study you linked is interesting- it does seem to confirm what I suspected, that HDPE does flow on knife impact causing it to release less plastic debris than other plastics, but still not zero. The second one seems to be a fairly low quality review article looking at what does sound like a concerning issue, but doesn't really consider different types of plastic independently. It might be useful in the sense of citing a lot of papers in this area that could be looked at directly.