That would depend on your extraction method, thin necks make retrieving immiscible solvents easier etc etc -- both are glass so are unlikely to contaminate you product but the contact time with your lids is quite minimal so contamination will be kept to the barest of minimums. Our bodies are pretty good at removing toxins and as I said there are contaminants everywhere in modern life so worrying over a lid seems a bit moot.

thanks for your input geeg30, i had the same thoughts about minimum contact with the lid leading to almost no contamination. Thanks for chipping in