Hi,
Are you referring to solvent based decaffeination? I don't think that's widely used anymore and it seems possible to find the process used by some of the major brands. I dont claim to know all the science or have all the facts but there's a few interesting reads out there as I agree you can't be too careful!!
Lavazza came up among one of the best tasting in an article I found (granted not a recent one) but anyway Lavazza use the C02 method for decaffeination which is not solvent based. I've read this claim too 'There are no residues or toxic by-products in this decaffeination method. In addition, CO2 is an organic substance of great purity, and in its supercritical state shows great promise as a replacement for toxic solvents across industries.' -https://lifespa.com/decaf-safe/
This also makes an interesting read about the various processes:
http://coffeeconfidential.org/health/decaffeination/
Anyway, if you prefer not to go the decaf route - I hope you can find a tasty alternative!