"The bellows are burned, the lead is consumed of the fire; the founder melteth in vain: for the wicked are not plucked away. Reprobate silver shall men call them, because the Lord hath rejected them."
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 published later that year, he argued that "lead poisoning contributed to the decline of the Roman empire." Yet, a review by Scarborough, a pharmacist and classicist, criticized the book as being "so full of false evidence, miscitations, typographical errors, and a blatant flippancy regarding primary sources that the reader cannot trust the basic arguments." Scarborough concluded that, although ancient authorities were aware of lead poisoning, it was not endemic in the Roman empire nor caused its fall. Waldron, a specialist in both occupational medicine and archaeology, also chastised the author for not using primary sources and being uncritical of the material he did use, concluding that "The decline of the Roman Empire is a phenomenon of great complexity and it is simplistic to ascribe it to a single cause."
Lead (Pb) does not occur in an elemental state but is a by-product of silver mining. Extracted from galena ore (PbS, lead sulfide), which is crushed and smelted, the lead alloy was further refined by the Romans in a furnace made hotter still by blasts of air forced from a bellows (Pliny, Natural History, XXXIII.95, 159). The oxidized lead (litharge, PbO), 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 itself then was recovered by smelting the litharge again with galena, the lead oxide combining with lead sulfide to form metallic lead and sulfur dioxide (2PbO + PbS = 3Pb + SO2).
Readily abundant (in Britannia, the ore was so near the surface that restrictions limited the amount that could be produced, Pliny, XXXIV.164), 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, On Architecture, VIII.6.1ff; Frontinus, On the Aqueducts of Rome, XXXVIIff).
Sheets of lead were used to line Roman aqueducts (as was cement) and lead pipes to convey water. But lead also was known to be unwholesome and, for that reason, pipes made of clay were preferred—as Vitruvius, who wrote during the time of Augustus, explains.
"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 [ceruse or 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).
Columella, too, remarks on the advantage of terracotta pipes. "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).
Rain water was known to have the least amount of contamination (Celsus, On Medicine, II.18.12). But it also is slightly acidic and dissolves carbon dioxide in the atmosphere to form a weak solution of carbonic acid, which in turn reacts with calcium hydroxide to form calcium carbonate (CaCO3). In his treatise on the aqueducts of Rome, Frontinus complains that "the accumulation of deposit, which sometimes hardens into a crust, contracts the channel of the water" (CXXII.1). The aqueduct at Nîmes, for example, had an accretion of calcium carbonate that accumulated approximately one millimeter per year (about four inches every century), constricting its channel by more than a third of its width. The frequent cleaning of this limestone encrustation (sinter, from the German) suggests that deposits of calcium carbonate in pipes and aqueduct channels protected against corrosion and insulated against the introduction of lead. Too, the water would have flowed continuously and not been in prolonged contact with the metal.
Rather than encrusted lead pipes, a more probable cause of chronic lead poisoning (plumbism or "saturnism" because its symptoms seemed indicative of the planet's characteristics) was the consumption of defrutum and sapa. Cato, Columella, Pliny, and Palladius (On Agriculture, XI.18) 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 that otherwise was sour or would spoil. Cato, for example, recommends that olives and pears be preserved in boiled must (VII.4) as does Varro (I.59.3). And Columella indicates that defrutum should always be boiled with quinces or some other flavoring (XII.20.2). Apicius, in De Re Coquinaria offers directions for preserving quinces in defrutum and honey (I.21) and added the rich syrup to many of his sauces to enhance the color and flavor of almost every dish, whether meat, fish, fowl, or fruit. (The fact that the reduction was used to color food indicates that red wine was used rather than white.)
The question is how the must was boiled and reduced, whether in pots of bronze or lead. If lead, there is a danger that the metal will be leached into the acidic juice; if copper, that the flavor of the juice will be affected by the formation of copper acetate (verdigris). 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; notice that the definition is not always consistent).
Theophrastus, a student of Aristotle, was the first to describe the production of copper-rust (copper acetate) from the reaction of the metal and wine lees, by which the acetic acid (vinegar) in soured wine reacts with copper oxide to form copper acetate (De Re Metallica, IX).
Pliny also recommends that the must be prepared in lead vessels.
"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).
It would seem therefore that the must was boiled in cauldrons of lead, although Scarborough 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 bronze cauldrons (copper and tin in alloy), not those of lead." But copper and bronze are suspect as well. Pliny writes that "When copper vessels are coated with stagnum [a lead alloy], the contents have a more agreeable taste and the formation of destructive verdigris is prevented" (XXXIV.160) and that the best bronze was alloyed with ten percent lead and tin (XXXIV.95). Still, Scarborough insists that the short boiling time would not have contaminated the juice.
Aside from whether the must was boiled in lead, assumptions also have to be made regarding how much defrutum was added to sweeten and preserve the wine, the amount of wine consumed, and its lead content. Eisinger found that must reduced to one-third its volume contained approximately one gram of lead per liter. If, as Columella recommends (XII.20.3), one sextarius of defrutum should be mixed with one amphora of wine, the resulting proportion would be one part in forty-eight or almost 21 milligrams per liter (mg/L). It is an extraordinary burden and certainly would induced symptoms of lead poisoning—even more so, if one follows Cato's recommendation of one part in thirty (XXIV).
Although there is no basis for such a quantification, Nriagu assumes the aristocracy of Rome to have consumed two liters of wine a day—almost three bottles, which would seem to make alcoholism more suspect than lead poisoning—and estimates the lead intake to have averaged 180 micrograms (µg) daily. Although the relationship between ingested lead and blood lead levels varies, and there is no way to quantify what Romans actually ate or drank, he further estimates the total amount of lead absorbed in the blood from all sources to be 50 micrograms per deciliter (µg/dL) or 0.5 mg/L. Three deciliters of such wine, the equivalent of two glasses, would therefore contain 150 µg of lead. Wine poured from Columella's amphora would contain 21,000 µg/L or 2,100 µg/dL.
Such levels have significant physiological consequences. As reported by the U.S. Department of Health and Human Services, there is brain and kidney damage in adults with blood lead levels of 100 µg/dL; gastrointestinal symptoms such as colic, with levels of approximately 60 µg/dL; anemia with levels of 50 to 80 µg/dL; neurological symptoms with levels of 40 to 60 µg/dL; depressed sperm count with levels of 40 to 50 µg/dL; and increased risk of preterm delivery, low birth weight, and impaired mental development with maternal blood lead levels of 10 to 15 µg/dL. The physiological insult to children would have been even greater. In children five years or younger, the Centers for Disease Control and Prevention recommends intervention when the level of lead in the blood is above even 5 µg/dL.
Nriagu's contention that "a large number of Roman aristocrats ingested more than enough lead with their foods and drinks each day to put them at risk for lead poisoning" may be correct. But to infer that the impact on fertility was one of the principle causes for the decline of the Roman empire is not. Twenty years before, Gilfillan had insisted that "lead poisoning is to be reckoned the major influence in the ruin of the Roman culture, progressiveness, and genius," a thesis convincingly refuted by Needleman and Needleman, who demonstrate that the decline of the Roman aristocracy can as easily be explained by a simple desire not to marry or to rear few or no children.
Augustus sought to promote marriage and encourage procreation by legislation (the Julian laws of 18/17 BC and the Lex Papia Poppaea a generation later in AD 9). "And yet, marriages and the rearing of children did not become more frequent, so powerful were the attractions of a childless state" (Tacitus, Annals, III.25). In a review of the life span of emperors and aristocrats, Scheidel dismisses any impact of lead ingestion on fertility. "Nor is there any need to suspect that the incidence of marital sterility in the Roman ruling class might have been much higher than in other groups, times, and places." And Drasch found that the average lead burden in Rome was not significantly higher than in the legionary camp and provincial capital at Augsburg. In Britain, the skeletal lead burden was even higher than in Rome. Still, Nriagu insists that "one of the principle, probable causes of the internal weaknesses" of the Roman empire was lead poisoning of the aristocracy.
Certainly, the Romans knew lead to be dangerous, even if they did not associate it with their lead cooking vessels. Pliny speaks of the "noxious and deadly vapour" (sulfur dioxide) of the lead furnace (XXXIV.167; there was a four-fold increase in atmospheric Pb pollution during the Greco-Roman period); white lead (cerussa) as a deadly poison (XXXIV.176), even though it was widely used as a medicine and cosmetic; and the power of sapa (and onion) to induce an abortion (XXIII.30). Dioscorides cautions against taking white lead internally, as it is deadly (Material Medica, V.103). Soranus in his Gynecology (I.19.61) recommends that the mouth of the uterus be smeared with white lead to prevent conception. Galen (De Antidotis, XIV.144) and Celsus (V.27.12b) both provide an antidote for poisoning by white lead, and Vitruvius remarks on the pernicious effects of water found near lead mines and its effect on the body (VIII.3.5, 6.11).
The earliest description of acute lead poisoning (mid-second century BC) is given in the Alexipharmaca of Nicander, who speaks of "gleaming, deadly white lead whose fresh colour is like milk which foams all over" (II.74ff). The poet describes a frothing mouth, asperity of the tongue, and dry throat, together with dry retching, chills, delusions, and overwhelming fatigue. But if lead poisoning had been endemic, it presumably would have been remarked upon at the time. And yet there is no mention of the fact until early in the seventh century AD, when Paul of Aegina, a Byzantine physician, described chronic lead poisoning (although he does not associate its symptoms with the disease). "I am of the opinion that the colic affection which now prevails is occasioned by such humours; the disease having taken its rise in the country of Italy, but raging also in many other regions of the Roman empire, like a pestilential contagion, which in many cases terminates in epilepsy, but in others in paralysis of the extremities, while the sensibility of them is preserved, and sometimes both these afflictions attacking together" (III.64).
It should be remembered that the Romans diluted their wine. Of the two liters that Nriagu estimates to have been drunk every day, if mixed with two parts water, only two-thirds of a liter actually would have been undiluted wine. An inscription from AD 153 indicates that junior members of the College of Asclepius and Hygia were allotted two sextarii of wine a day, and senior members, nine sextarii, the equivalent of approximately one to five liters. And Cato allotted his slaves seven quadrantals (amphorae) of wine a year, allocated according to the month (On Agriculture, LVII). During the summer months, the allowance was a sextarius (about half a liter) per day, with more for the Saturnalia and, a few days later, the Compitalia.
Smaller vessels have a larger surface area relative to their volume. The four-liter pot used by Patterson et al. to determine the amount of dissolved lead presumably would leach out more of the metal than the huge oiled cauldron mentioned by Columella (XII.20.3), in which ninety amphorae (approximately 2340 liters) of must remained after boiling.
Defrutum was only one of several remedies to sweeten or preserve potentially sour wine (Pliny, XIV.121). Sea water and resin also were added, as was lead acetate (sugar of lead), which was formed by treating litharge with acetic acid (the component that gives vinegar its sour taste and pungent smell). Martial accuses a wine merchant of Marseilles of shipping poisonous and overpriced wines to his friends and, indeed, being reluctant to visit Rome for fear of having to drink them himself (Epigrams, X.36). Pliny, too, complains that "genuine, unadulterated wine is not to be had now, not even by the nobility" (XXIII.1), ruefully remarking "So many poisons are employed to force wine to suit our taste—and we are surprised that it is not wholesome!" (XIV.130). Indeed, "So low has our commercial honesty sank that only the names of vintages are sold, the wines being adulterated as soon as they are poured into the vats. Accordingly, strange though it may seem, the more common the wine is today, the freer it is from impurities" (XXIII.34).
Columella regarded "as the best wine any kind which can keep without any preservative, nor should anything at all be mixed with it by which its natural savour would be obscured; for that wine is most excellent which has given pleasure by its own natural quality" (XII.19.2). Further, "care must be taken that the flavour of the preservative is not noticeable, for that drives away the purchaser" (XII.20.7).
Writing several decades later in the first century AD, Dioscorides says much the same thing. "Generally, all unmixed and simple wine (hard by nature) is warming, easily digested and good for the stomach. It encourages the appetite, is nourishing, induces sleep, and causes a good colour" (Material Medica, V.11). Those with sapa, however, "fill the head causing drunkenness." One should drink moderately and (because alcohol is a diuretic and dehydrates the body) drink water both before and afterwards, "for it brings some help in avoiding illness owing to drunkenness."
The best tasting wine likely would not have been adulterated and presumably was the very wine drunk by the nobility, who supposedly were most at risk for lead poisoning. More than wine or water transported through lead pipes, the dainties and elaborate sauces prepared with defrutum by gourmands such as Apicius are likely to have been the primary source of ingested lead by the Roman aristocracy.
"What I tell you three times is true."
A cautionary note: One reads that Hippocrates described lead colic in a man who was a metal worker, or that he was the first to do so and that this occurred in 370 BC. The primary source for these statements is almost never given, although the Encyclopaedia Britannica Online does say in its entry on Occupational Disease: The preindustrial era that "The first recorded observation of an occupational disease may be a case of severe lead colic suffered by a worker who extracted metals. It is described in the third book of Epidemics, attributed to Hippocrates." There is mention of painful colic and constipation in Part 8 of that book, but the symptoms are not attributed to lead nor to lead workers. It is facile to assume that, because Romans used lead and reported symptoms concomitant with lead poisoning, they were caused by lead—or, to phrase it another way, that if lead poisoning can have almost any symptom, then almost any symptom can be attributed to it. While Hippocrates may have known about lead poisoning, Waldron cautions that he "did not describe it in any of the books which have come down to us."
"But the Goths kept pressing vigorously upon them, shooting many missiles at the battlements, and they were already about to set their ladders against the wall, having practically surrounded those who were fighting from the tomb; for whenever the Goths advanced they always got in the rear of the Romans on both flanks; and for a short time consternation fell upon the Romans, who knew not what means of defence they should employ to save themselves, but afterwards by common agreement they broke in pieces the most of the statues, which were very large, and taking up great numbers of stones thus secured, threw them with both hands down upon the heads of the enemy, who gave way before this shower of missiles."
Procopius is relating the Siege of Rome by the Goths in AD 537. The Barberini Faun (above) was discovered early in the seventeenth century at Hadrian's Tomb (Castel Sant'Angelo) and may have been one of the pieces thrown from the wall. Named for the cardinal who owned it early in the seventeenth century, it now is in the Glyptothek (Munich), which was constructed to house the sculpture collection of Ludwig I of Bavaria, who had a room designed specifically for his prize statue.
"[Trajan] in his wisdom and authority and devotion to the people has opened roads, built harbours, created routes overland, let the sea into the shore and moved the shore out to sea, and linked far distant peoples by trade so that natural products in any place now seem to belong to all."
Pliny the Younger, Panegyricus (XXIX)
In AD 62, Tacitus recorded that a violent storm sank two hundred ships at Portus, Rome's harbor at the mouth of the Tiber (Annals, XV.18). Begun twenty years earlier by Claudius and completed by Nero in AD 64, the port served as an anchorage for ships waiting to unload their cargo onto river barges for transport up the Tiber. But it also was exposed to the sea and may have been inundated by a tsunami, the result that year of an earthquake which devastated Pompeii (Seneca, Natural Questions, VI). It was an extraordinary maritime disaster that may have prompted Trajan to begin the construction in AD 103 of a more sheltered harbor farther inland (Suetonius, Life of Claudius, XX.3; Dio, LX.11.1ff; cf. Juvenal, Satires, XII.75ff: "the still waters of the inner basin").
Surrounded by a complex of large warehouses and granaries, a temple and elaborate administration building and imperial residence, this hexagonal basin, which measured 1175 feet along each side, had pierced mooring bollards for one hundred-twenty ships along its five sides. De Graauw has calculated that as many as two hundred-eighty ships could be accommodated, with some being anchored in the middle of the harbor until berths became free. Trajan also constructed a canal (Canale Romano) that ran parallel to the warehouses on one side of the harbor to facilitate the transshipment of goods and alleviate silting of the river (Pliny the Younger, Epistles, VIII.17.1), which had backed up in AD 69 and caused severe flooding in Rome and the loss of its granaries (Plutarch, Life of Otho, IV.5; Tacitus, Histories, I.86).
In a 2014 study, Delile et al. sought to determine the concentration of lead isotopes in the sediment of the harbor. Core samples were taken from the channel that connected the Trajanic basin to the Claudian harbor and from the Canale Romano. It was found that "Lead isotopes in sediments from the harbor of Imperial Rome register the presence of a strong anthropogenic component....[which] demonstrate that the lead pipes of the water distribution system increased Pb contents in drinking water of the capital city by up to two orders of magnitude over the natural background." Compared to local spring water, this level was forty time greater in the early Roman empire (AD 100-250), although it is "unlikely to have been truly harmful."
The inference is that these isotopes were deposited by the discharge of contaminated water from lead pipes (fistulae) in Rome. Although harbors are "excellent sedimentary traps," the enclosed basin at Portus may have concentrated an artificially high burden of lead in the core sample. Too, there is a confounding variable: the amount of lead already in the harbor sediment (aside from what was naturally present). The anchors of ships, for example, had lead stocks and braces, and hulls were covered in lead to protect against shipworm, sheathing that was periodically scraped to prevent fouling, which further distributed the metal. Lead ingots were carried as cargo and sometimes as ballast; lead weights were used to sound for depth and sink fishing lines; lead brailing rings were attached to lines and sails; and lead pumps emptied ships' bilges. Lead also was used to counter-balance rudder and rowing oars, and to caulk deck seams. If ships sank in the harbor, as they did, this lead, as well as the lead cooking pots and utensils onboard, were lost as well. A vast shipyard discovered in 2011 only would have added to the detritus flushed into the basin. Too, ancient lead was exceptionally pure. (Controversially, lead ingots salvaged from ancient shipwrecks have been melted and reused to shield instruments in the detection of dark matter).
In contrast to Rome, the water supply of Alexandria was conveyed, not through lead pipes, but by a canal (an inscription records it being restored by Augustus in AD 10-11) that brought water from the westerly (Canopic) branch of the Nile around the southern boundary of the city. A system of conduits beneath the streets then channeled that water into underground cisterns cut into the rock (Caesar, Alexandrian War, V) where the heavy load of sediment settled, allowing the clear water to be drawn off.
Véron et al. conducted a similar study of lead isotopes in the sediment of the ancient harbor at Alexandria and found that concentrations of lead doubled during the Roman period (AD 100-300), rising to 600 parts per million. It was "the highest Pb pollution ever encountered in ancient city sediments....an order of magnitude higher than those measured in sediment deposits from Sidon, the only other ancient harbor to have undergone similar geochemical investigation." Such levels would seem to argue that similar lead pollution in the harbor of Portus was not causally related just to the use of lead fistulae in Rome.
The enlargement of Portus was in response to the greater supply of grain being imported to Rome, much of it being diverted from the port at Puteoli on the Bay of Naples. In a letter written shortly before his enforced suicide in AD 65, Seneca marveled at the arrival of the Alexandrian grain fleet at Puteoli. No matter how great the number of vessels in the harbor, those sent ahead of the fleet always were conspicuous by their topsails. Whereas other ships pulled them in when the wind became too strong, depending only on their mainsails, the Alexandrians kept their topsails spread (Epistulae Morales ad Lucilium, LXXVII.1-2).
The reverse of these commemorative sesterces (above) commemorate the inauguration of the Portus Trajani, which was constructed about AD 103-111.
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Vitruvius: Ten Books on Architecture (2001) edited by Ingrid D. Rowland and Thomas Noble Howe; Lucius Junius Moderatus Columella: On Agriculture (1954) translated by E. S. Forster and Edward H. Heffner (Loeb Classical Library); Marcus Porcius Cato: On Agriculture and Marcus Terentius Varro: On Agriculture (1935) translated by William Davis Hooper, revised by Harrison Boyd Ash; Pliny: Natural History (1945) translated by H. Rackham (Loeb Classical Library); Frontius: Stratagems, Aquducts (1925) translated by Charles E. Bennett (Loeb Classical Library); The Seven Books of Paulus Aegineta (1844) translated by Francis Adams; Celsus: On Medicine (1938) translated by W. G. Spencer (Loeb Classical Library); Apicius: De Re Coquinaria (1936/1977) translated by Joseph Vehling (Dover Books); Soranus' Gynecology (1956) translated by Owsei Temkin; Hippocrates: Epidemics I & III (1923) translated by W. H. S. Jones (Loeb Classical Library); The Fourteen Books by Palladius Rutilius Taurus Ćmilianus on Agriculture (1807) translated by T. Owen; Procopius: The Gothic War (1919) translated by H. B. Dewing (Loeb Classical Library); Dioscorides Pedanius of Anazarbus: De Materia Medica (2005) translated by Lily Y. Beck; Pliny the Younger: Letters and Panegyricus (1969) translated by Betty Radice (Loeb Classical Library).