There’s no safe way to approach a manchineel tree, as every part of it is toxic. One touch is enough to cause severe skin irritations and eye injuries that can leave you temporarily blind. Simply standing under a manchineel tree while its raining can even cause pain. It’s also a bad idea to burn its lumber, as the smoke is harmful as well.

From the article.

[–] frongt@lemmy.zip 3 points 1 month ago

Yes, I read the article. But mentalfloss is not a reliable source.

https://edis.ifas.ufl.edu/publication/FR370

This is indeed the tree I was thinking of, and yes it's the sap that's toxic. Dry bark should be safe to touch, but it does weep sap through its bark. The interior wood, leaves, and fruit all contain the sap, so you should absolutely not interact with those without protection.