I'm confused by your mention of glyphosate. It clearly has a lot of negative externalities, but are you including it as a possible x-risk or just a note like "something along the lines of what happened by glyphosate but way worse"? If the latter, which angle are you talking about--the one where some new herbicide comes out, and everyone adopts it for economic reasons, then it turns out to be bad (like an order of magnitude worse than glyphosate was)?
I knew that glyphosate is a bad example here, as it is not experiment, so it is more like a placeholder. What I mean is that current scientific research is producing enormous number of new never existing chemicals and some may have unexpected consequences. Actually I wrote a draft “Global catastrophic rusks by chemical contamination”. https://philpapers.org/rec/TURGCR-2 In it I explored more ideas how chemical things could go wrong.
I can't embed an image here for some reasons, may be it is too large, so here is a link on pdf
http://immortality-roadmap.com/risks%20of%20scientific%20experiments4.pdf