Fall Of Roman Empire

A 1983 article in the New England Journal of Medicine by Jerome Nriagu, a geochemist, reopened a debate that had been dormant for almost two decades. There, and in a book later that year, he argued that "lead poisoning contributed to the decline of the Roman empire." Yet, a review by John Scarborough, a pharmacist and classicist, has criticized the 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" and concluded that, although ancient authorities were aware of lead poisoning, it was not endemic in the Roman empire nor caused its fall.

This criticism is apparent even to a non-classicist. In De Architectura, for instance, Vitruvius, who wrote during the time of Augustus, indicates that the Romans knew of the danger of lead pipes and, consequently, that terracotta was preferred.

"Water conducted through earthen pipes is more wholesome than that through lead; indeed that conveyed in lead must be injurious, because from it white lead [cerussa, lead carbonate, PbCO3] is obtained, and this is said to be injurious to the human system. Hence, if what is generated from it is pernicious, there can be no doubt that itself cannot be a wholesome body. This may be verified by observing the workers in lead, who are of a pallid colour; for in casting lead, the fumes from it fixing on the different members, and daily burning them, destroy the vigour of the blood; water should therefore on no account be conducted in leaden pipes if we are desirous that it should be wholesome. That the flavour of that conveyed in earthen pipes is better, is shewn at our daily meals, for all those whose tables are furnished with silver vessels, nevertheless use those made of earth, from the purity of the flavour being preserved in them" (VIII.6-10-11).

A by-product of silver mining, lead (Pb) was extracted from galena ore (PbS, lead sulfide), which was crushed and smelted (Pliny, XXXIII.95, 159). The lead alloy then was further refined in a furnace made hotter still by blasts of air forced from a bellows. The oxidized lead (PbO, litharge), which was contained in a porous crucible of crushed bone ash, was absorbed, leaving behind a trace amount of silver in a process called "cupellation" (from the cupel used to collect the metal). The lead was recovered by smelting the bone ash again with galena, the lead oxide combining with lead sulfide to form metallic lead and sulfur dioxide (2PbO + PbS = 3Pb + SO2).

Abundant, easily malleable, and with a low melting point (low enough, in fact, to melt in a camp fire), lead (plumbum) was ideal for the production of water pipes, which were fabricated by plumbarii (plumbers) from fitted rolled sheets in a variety of diameters (Vitruvius, VIII.6.1ff). Such pipes were extensively used but also known to be a potential source of soluble lead. How then to reconcile the two realities?

In his treatise on the aqueducts of Rome, Frontius complains that "the accumulation of deposit, which sometimes hardens into a crust, contracts the channel of the water" (122). Rome is situated on calcareous rocks, and the frequent cleaning of such limestone encrustation suggests that deposits of calcium carbonate in the pipes protected against corrosion and insulated against the introduction of lead into the water. Even though the literary evidence suggests a preference for rain or spring water, which would be more acidic, these accumulated salts would have provided a protective barrier. The water also is likely to have flowed continuously and so not have been in prolonged contact with lead. And it also would have run through terracotta pipes. Indeed, Columella remarks that "Rain-water is after all most suitable to the body's health, and is regarded as uncommonly good if it is conveyed through earthen pipes into a covered cistern" (I.5.2; Celsus II.18.12).

Rather than lead pipes, a more probable cause of lead poisoning (plumbism) in ancient Rome was the consumption of defrutum or sapa. Cato, Columella, and Pliny all describe how unfermented grape juice (mustum, must) was boiled to concentrate its sugar. "A product of art, not of nature," says Pliny (XIV.80), the must was reduced to one half (defrutum) or even one third its volume (sapa), and the thickened syrup used to sweeten and preserve wine and fruit. Apicius, for example, in De Re Coquinaria offers directions for preserving quinces in defrutum and honey (I.21), and uses "reduced must" in many of his sauces to add color and flavor to almost every dish, whether meat, fish, fowl, or fruit. Cato, too, recommends that olives and pears be preserved in boiled must (VII.4).

The question is whether the must was boiled in pots of lead or bronze. In De Agri Cultura, the earliest example of Latin prose (c.160 BC), Cato gives directions for reducing must in "a copper or lead vessel" over a slow fire, "stirring constantly to prevent scorching; continue the boiling, until you have boiled off a half" (CVII). Writing in the first century AD, Columella elaborates on the process.

"Some people put the must in leaden vessels and by boiling reduce it by a quarter, others by a third. There is no doubt that anyone who boiled it down to one-half would be likely to make a better thick form of must and therefore more profitable for use....But, before the must is poured into the boiling-vessels, it will be well that those which are made of lead should be coated inside with good oil and be well-rubbed, and that then the must should be put in....The vessels themselves in which the thickened and boiled-down must is boiled should be of lead rather than of brass; for, in the boiling, brazen vessels throw off copper-rust and spoil the flavour of the preservative....Must of the sweetest possible flavour will be boiled down to a third of its original volume and when boiled down, as I have said above, is called defrutum" (XII.19.1, 19.6, 20.1, 21.1).

Pliny, too, in his Natural History (AD 77) recommends that must be prepared in a lead vessel.

"Also boiled-down must and must of new wine should be boiled when there is no moon, which means at the conjunction of that planet, and not on any other day; and moreover leaden and not copper jars should be used, and some walnuts should be thrown into the liquor, for those are said to absorb the smoke" (XIV.136).

Even though it would seem that must was boiled in lead, Scarborough, himself, is reluctant to weaken his case, insisting that "one needs to read these texts carefully which mention a 'preference' for lead over bronze to realize that the Romans most often used