The Romans killed themselves with lead flatware and tableware. We’re doing it with “the synthetic estrogen used in birth-control pills” and other animal growth hormones — that are WAY too persistent in the ecosystem.
As for the Roman Empire, If you include the eastern part of the Roman empire, Byzantium, all told, it arguably lasted over 1,650 years. I think we can rule out a sudden rash of lead poisoning. It was Islamic poisoning.