Microplastics have been in the news and the local rationalist discord with increasing frequency over the past few months. Of note are Nat Friedman's PlasticList, and this 2024 preprint demonstrating that some human brains are now 0.5% plastic by weight. There was also an article on black plastic cookware that was quickly retracted[1]. The volume of discussion made it clear that few people seem to have a clear understanding of what we actually know about microplastics, so we had a meetup about it.

Here are the notes from Kitchener-Waterloo Rationality's in-person meetup[2] researching the current understanding of microplastics in a time-boxed format. Sort of like partitioned book club, the goal of the meetup was to power of friendship teamwork our way into a better understanding of a complex topic with relatively little individual effort.

tl;dr: The field is so new that there's a striking lack of scientific consensus [...]

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Outline:

(01:59) What are the current recommended limits for microplastic intake?

(02:06) Canada

(02:44) EU

(02:56) USA

(05:42) World Health Organization

(06:25) Recommended Limits For Specific Chemicals Exist

(07:34) A Good Paper on Microplastic Regulation Meta

(09:15) Health Effects of Microplastics

(12:33) Quantities Ingested and Main Exposure Pathways

(18:06) Food contamination

(20:49) Household dust

(23:19) How to reduce the amount of microplastics you have

(23:32) Misc links

(26:21) Appendix: Research Agenda and Format

The original text contained 3 footnotes which were omitted from this narration.

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Narrated by TYPE III AUDIO.