They used several various reactions (w acetonitrile, PSA, MgSO4, C18) to selectively dissolve / isolate the plastic compounds. This is also assisted by certain techniques (sonication, GC-MS/MS). They also added isotopically-labeled control plastic samples. That should enable them measure matrix affects and adjust for them in the non-control sample.

It is the isotopic labels that give me the most assurance.

While the ziploc bags had pthalates, I agree that it is probably not enough to impact the results, especially considering the lab used acetonitrile on the bags to test them. There's also the hand soap. These would probably cause a difference of + 80 at most.

Overall, I'd say the tests were the best we can get with current techniques / technology.

To fully assess the health impact of ingested plastics, we have to establish the underlying mechanism (e.g. bioaccumulation + endocrine activity) as well as the pattern of health consequences in real-world data.

The first part is easier and I believe has been demonstrated (especially regarding endocrine activity) fairly well.

The latter is notoriously difficult; it is probably better approached with animal studies as human association studies are too unreliable and would take too long to tease out effects.

Dosage is also an important factor and often makes poison-in-principle not poison-in-practice, though low-dosages over a long period of time may still have an effect that is not immediately noticeable. Bioaccumulation is also related to this.

As for the "plastic spoon" claim, it originated from this study -- https://pmc.ncbi.nlm.nih.gov/articles/PMC12003191 -- in Nature.

The study you list is specific to analysis of human blood, whereas the original was done on human brain tissue. The original study cites other papers that have demonstrated the accumulation of plastics in other organ tissues using different techniques so I wouldn't discount plastics research because of the potential flaws of one method. Plus the fact that in the original study, the level of plastics increased by 50% between those who died in 2016 vs 2024 and increased further in those with dementia suggests that there is a real relationship here and something to be concerned about.

There are many other studies that establish a negative health relationship here. I don't think we should discount them.