Many of the Emperors died childless and Senatorial families kept dying out. The reason seems simple: lead poisoning. Bones of the Classical period have been found to contain lead, but those of the periods before and after were free from it. The lead was got from pipe, cooking utensils, recipes and cosmetics. The Romans knew about acute plumbism but the slow chronic form was unnoted. Lead piles up in the body, at first with no apparent harm, but then, as the content rises and if the body grows more acid, lead is drawn out with calcium from the bones and the individual becomes sick. The symptoms are variable and the Romans could not have grouped them together – constipation, anaemia, loss of appetite, pains in the joints, and in further stages, headache, insomnia, blindness and mental disturbances. An important point is that the toxic condition induces sterility and such children as are born are prone to premature death.
Lead was the only available metal cheap enough for common use, which could be joined by welding and which (except for copper) could be cast. Roman pottery was weak and porous and conducted heat badly. Acid food left in a copper pot turned green, had an unpleasant taste and induced sickness; but lead seemed to have no disadvantages. Leaden vessels, lead-lined copper ones, were used for acid foods including most vegetables, especially for boiling.
– Historian Jack Lindsay.