<P> Thirty years ago, Jerome Nriagu argued in a milestone paper that Roman civilization collapsed as a result of lead poisoning . Clair Patterson, the scientist who convinced governments to ban lead from gasoline, enthusiastically endorsed this idea, which nevertheless triggered a volley of publications aimed at refuting it . Although today lead is no longer seen as the prime culprit of Rome's demise, its status in the system of water distribution by lead pipes (fistulæ) still stands as a major public health issue . By measuring Pb isotope compositions of sediments from the Tiber River and the Trajanic Harbor, the present work shows that "tap water" from ancient Rome had 100 times more lead than local spring waters . </P> <P> Romans also consumed lead through the consumption of defrutum, carenum, and sapa, musts made by boiling down fruit in lead cookware . Defrutum and its relatives were used in ancient Roman cuisine and cosmetics, including as a food preservative . The use of leaden cookware, though popular, was not the general standard and copper cookware was used far more generally . There is also no indication how often sapa was added or in what quantity . </P> <P> The consumption of sapa as having a role in the fall of the Roman Empire was used in a theory proposed by geochemist Jerome Nriagu to state that "lead poisoning contributed to the decline of the Roman Empire". In 1984, John Scarborough, a pharmacologist and classicist, criticized the conclusions drawn by Nriagu's book as "so full of false evidence, miscitations, typographical errors, and a blatant flippancy regarding primary sources that the reader cannot trust the basic arguments ." </P> <P> After antiquity, mention of lead poisoning was absent from medical literature until the end of the Middle Ages . In 1656 the German physician Samuel Stockhausen recognized dust and fumes containing lead compounds as the cause of disease, called since ancient Roman times morbi metallici, that were known to afflict miners, smelter workers, potters, and others whose work exposed them to the metal . </P>

Lead poisoning is an example of which factor