Hi cristalyte,
Eco-Institut is a testing organization that tests products including testing latex for offgassing and harmful chemicals and purity. It’s one of the more common latex testing protocols along with OekoTex and a few others.
Sleep Warhouse is included on the list of better topper or component sources in post #4 here. I’m not so sure I would trust their latex ILD numbers though because their ILD’s don’t match the density of their Dunlop layers .,… especially the soft which is likely much firmer if it is really 4.7 lb density.
I’d probably choose a medium firmness (Dunlop doesn’t come in exact ILD’s) which would typically be in the low 30’s or so.
Phoenix