Tomatoes never were poisonous.

Centuries ago both the peasants and the non-peasants ate from elaborately decorated pewter trenchers. They devoured anything that was edible and if it mattered, presented to the fitness of a king's tastes. This included tomatoes, usually imported from Spain or grown in the fields and palace gardens.

Unbeknownst to the consumers, the acids in tomatoes extracted the lead from the trenchers and made its way to the guts of these overfed and understimulated courtly people. During the experience of lead poisoning, death was wished for and for many it was the only outcome.

Before this crudely scientific discovery, it was the kitchenhands, chambermaids and gamekeepers who were accused of intentional poisoning, in fact, any 'nobody' who wasn't of regal lineage. Unfairly, it was these people who were given the death penalty, much to the amusement of everybody since life was rather boring and anything that was not so mundane was a welcome change.

Remember, never eat or drink from lead utensils. Keep them with Aunty Nancy's paintings in the attic.