1) - Do they still use lead-containing gasoline in Portugal? If so, it seems reasonable that lead-containing deposits from automobile exhaust might well contaminate roadside vegetation, which theoretically could become concentrated in the tissues of snails which feed on that vegetation. I don't know if any actual studies have been done to establish this. It would be an interesting question to explore. I have seen warnings against gathering edible plants from such areas, so I would be suspicious of snails feeding on those same plants. If the snails are lead-contaminated, no manner of cooking will remove the metal. 2) - I know of no normal human parasite that uses land snails as an intermediate host, though there are plenty of fresh water snails that serve as vectors of human parasites. By "normal" I mean parasites whose usual final host is humans. There are some very rare cases of bovine lungworm infection in humans, and certain terrestrial slugs and snails do serve as intermediate hosts for such parasites. Cows get infected by inadvertently consuming snails along with the grass they eat. But those snails, while I don't remember the exact genera involved, are tiny species, not the larger forms usually eaten by humans. And, to become infected with anything from a snail, you would have to eat the snail uncooked. Paul M.