Why Lead Poisoning Probably Did Not Cause the Downfall of the Roman Empire

Many people seem to have the impression that everyone in ancient Rome suffered from lead poisoning because the Romans used pipes made of lead. Indeed, many people seem to think that this was a major contributing factor in the decline of the Roman Empire. This idea is largely inaccurate, but there is some truth behind it. It is certain that some people in ancient Rome did suffer from lead poisoning. Nonetheless, we have very little evidence to indicate that lead poisoning was ever a widespread ailment on the scale that most people seem to imagine. Contrary to popular speculation, it is highly unlikely that lead poisoning played a significant role in the decline and fall of the Roman Empire. It is also highly unlikely that lead poisoning made any Roman emperors go insane.

Greek and Roman knowledge of lead poisoning

It is often stated that the Greeks and Romans did not know that lead was poisonous, but this is only partially true. The general public certainly did not know lead was poisonous, but many educated Greeks and Roman writers did. In fact, as we shall see in a moment, in some cases, these writers not only knew that lead was poisonous, but actively warned others not to use lead. These people can only have known that lead was poisonous from observing people actually suffering from lead poisoning, so we must conclude that lead poisoning certainly did exist in ancient times.

The Greek poet and physician Nikandros of Kolophon, who lived in around the second century BC, wrote a poem, which is included in his work Alexipharmaka. In this poem, Nikandros describes in detail the effects of severe lead poisoning. Nikandros writes, as translated in prose by A. S. F. Gow and A. F. Scholfield:

“In second place consider the hateful brew compounded with gleaming, deadly white lead whose fresh color is like milk which foams all over when you milk it rich in the springtime into the deep pails. Over the victim’s jaws and in the grooves of the gums is plastered an astringent froth, and the furrow of the tongue turns rough on either side, and the depth of the throat grows somewhat dry, and from the pernicious venom follows a dry retching and hawking, for this affliction is severe; meanwhile his spirit sickens and he is worn out with mortal suffering. His body too grows chill, while sometimes his eyes behold strange illusions or else he drowses, nor can he stir his limbs as heretofore, and he succumbs to the overwhelming fatigue.”

This is a fairly accurate description of the symptoms of lead poisoning.

ABOVE: Tenth-century AD illustration by an unknown illustrator from a Byzantine manuscript of Nikandros of Kolophon’s Theriaka. Nikandros is the first ancient writer to give a detailed account of lead poisoning.

About a century later, the Roman engineer Marcus Vitruvius Pollio (lived c. 80 – after c. 15 BC) writes in his treatise On Architecture, Book Eight, chapter six, sections ten through eleven, as translated by Morris Hicky Morgan:

“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 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.”

Ironically, despite warning about the toxicity of lead, in the same book, Vitruvius also describes numerous designs for lead water conduits.

ABOVE: Fictional illustration by the engraver Jacopo Bernardi, dating to the early nineteenth century, intended to represent the Roman architect Marcus Vitruvius Pollio. Vitruvius warned against the use of lead pipes, noting that lead was injurious to people’s health.

Other writers from later periods also mention the toxicity of lead. For instance, the Roman encyclopedist Aulus Cornelius Celsus (lived c. 25 BC – c. 50 AD) mentions in his work De Medicina that white lead is poisonous. The Greek physician Pedanios Dioskourides (lived c. 40 – c. 90 AD), who worked as a physician in the Roman military, correctly observed in his book De Materia Medica that exposure to lead has a deleterious effect on the mind and that oral consumption of lead is potentially fatal.

Knowledge of the existence of lead poisoning persisted among the educated even after the collapse of the western portion of the Roman Empire. In the seventh century AD, the Byzantine doctor Paulos of Aigina (lived c. 625 – c. 690) gave a detailed and accurate description of the symptoms of chronic lead poisoning in his medical encyclopedia Medical Compendium in Seven Books.

In other words, many people in ancient Rome who were among the educated elite were apparently well enough aware that lead was poisonous and some of these people even tried to make others aware of this. In spite of this, the general public was largely unaware of the dangers of lead poisoning, which is the reason why they continued to use lead for their pipes and vessels for storing beverages.

ABOVE: Fictional illustration intended to represent the Byzantine physician Paulos of Aigina from a printed text from 1574

It wasn’t the lead pipes…

Although modern theories about lead poisoning in ancient Rome almost invariably seem to focus on the fact that the Romans used lead pipes, most lead poisoning in ancient times actually did not come from the pipes. In fact, it is generally thought among historians that, although ancient Roman tap water did contain higher amounts of lead than tap water today, it probably did not usually contain a high enough concentration of lead to actually be harmful.

This was due to two reasons. The first reason is because a thick residue of calcium carbonate quickly built up on the insides of Roman lead pipes, insulating the water from the lead of the pipes. The second reason is because the water in the pipes was always running, meaning it was not in the pipes for long enough to actually become seriously contaminated.

A study conducted in 2014 estimated that, although ancient Roman tap water probably contained around 100 times as much lead as the water from local springs, the estimated lead concentrations were still probably not high enough to be harmful. The study’s conclusion states:

“This work has shown that the labile fraction of sediments from Portus and the Tiber bedload attests to pervasive Pb contamination of river water by the Pb plumbing controlling water distribution in Rome. Lead pollution of “tap water” in Roman times is clearly measurable, but unlikely to have been truly harmful. The discontinuities punctuating the Pb isotope record provide a strong background against which ideas about the changing character of the port can be tested.”

ABOVE: Photograph from Wikimedia Commons showing a variety of ancient Roman lead pipes from Ostia Antica

…it was the lead containers.

Ironically, it was not so much the lead pipes you had to worry about as lead containers. Upper-class Romans sometimes used lead vessels to hold drinks, especially wine. Lead poisoning from these lead vessels were probably much more common than lead poisoning from the lead pipes.

Unlike the pipes, these lead vessels did not develop a residue of calcium carbonate that could protect the liquid kept inside from becoming contaminated. Furthermore, while the water in the pipes was continuously flowing, the wine stored in these lead vessels would have sat in the vessel for days or even months, giving the lead more than enough time to contaminate it.

The most common source of lead poisoning in ancient Rome was probably not from lead pipes, but rather from various kinds of grape juices known as defrutum or sapa that had been boiled down in lead pots to half or a third of the juice’s usual volume in order to concentrate its natural sugars and make it taste sweeter. Although the Romans sometimes also used bronze pots for doing this, the preference seems to have been for lead pots.

The ancient Roman encyclopedist Pliny the Elder (lived c. 23 – 79 AD) remarks in his Natural History that consuming sapa sometimes had negative effects on certain individuals, although he does not link these negative effects to the lead pots that were often used for making it. Today, though, we can guess that the most likely cause of these ill effects mentioned by Pliny is lead poisoning from the lead pots that were often used for preparing the sapa.

Of course, while everyone in ancient Rome drank water, not everyone drank sapa and not everyone drank wine that had been stored in lead storage vessels. Ironically, most Romans who were not wealthy probably could not regularly afford lead containers and instead stored their wine in ceramic containers, which were much cheaper and much more common. Furthermore, sapa was not always made in lead pots, since, as I mentioned before, bronze pots were used for making it as well. Finally, the level exposure to lead from drinking sapa or wine that had been stored in lead containers probably varied considerably.

ABOVE: Imaginative sculpture intended to represent Pliny the Elder from the Cathedral of S. Maria Maggiore in Como, Italy. Pliny mentions that some people suffered negative effects from consumption of sapa, which was usually prepared using lead pots.

Did lead poisoning cause the downfall of Rome?

In a word, no. We have very little evidence to indicate that lead poisoning played any significant role in the decline of the Roman Empire. Furthermore, the Roman Empire existed for centuries. Romans were using lead for their pipes, for food storage, and for cooking that whole time. It seems unlikely that lead poisoning would suddenly only become a massive problem near the end of the Roman Empire, after centuries of people using lead.

Furthermore, we have no evidence that symptoms of lead poisoning were common in late antiquity. If everyone in late antiquity was suffering from symptoms of lead poisoning, you would think that someone would have noticed and mentioned it somewhere, especially since we know that at least some educated writers during this time period were aware that lead is poisonous and some even knew the symptoms of lead poisoning.

Instead, it seems more likely that the gradual decline of the Roman Empire was due to a variety of complex political, social, economic, and environmental factors. If lead poisoning played any role at all, it certainly played a very small one.

Surely lead poisoning made all the emperors go crazy, though, right?

A lot of people have the impression that many Roman emperors were crazy because they were suffering from severe lead poisoning. This is highly unlikely. For one thing, we have very little reliable evidence that Roman emperors were actually insane. Even when it comes to the most famous emperors who were supposedly insane according to modern popular culture, a thorough examination of the evidence reveals that they were probably not really as crazy as most people today seem to think after all.

Take Caligula as an example. We all know him as the mad emperor who supposedly once declared war on Neptune, then ordered his soldiers to attack the sea and take seashells as booty. The problem is that this story and the others like it all come from extremely late, hostile sources such as the biography Life of Caligula by Gaius Suetonius Tranquilus (lived c. 69 – after c. 122 AD) and Roman History by Kassios Dion (lived c. 155 – c. 235 AD).

These writers were highly motivated to portray Caligula as insane because they worked for later emperors who had motivation to portray earlier emperors as worse so they would look better by comparison. Suetonius was a secretary for the emperors Trajan and Hadrian. Kassios Dion was a consul under the emperor Severus Alexander.

When we only look at contemporary sources, a slightly different, less over-the-top portrait of Caligula emerges. For instance, the Jewish Middle Platonist philosopher Philon of Alexandria (lived c. 20 BC – c. 50 AD) gives an account of his personal meeting with Caligula in his work Embassy to Gaius. Philon portrays Caligula as an extremely arrogant, self-obsessed, rude, profligate, and occasionally bloodthirsty young man—but still very much sane.

ABOVE: Roman marble bust of the emperor Caligula from the Glyptothek Museum in Munich, Germany

The same thing happens when we examine other Roman emperors. Few, if any of them, were truly insane in the sense of being completely delusional and totally unable to make rational decisions.

There is also another reason why it is unlikely that many Roman emperors suffered from severe lead poisoning and that is that lead poisoning has other symptoms aside from just making people “go crazy.” As we have discussed, some ancient writers were aware of these symptoms and yet, for some reason, we have little evidence that it was at all common for Roman emperors to suffer from these symptoms. This seems to indicate that lead poisoning was not a common ailment among Roman emperors.

Conclusion

It turns out the ancient Romans were a lot more intelligent than many people give them credit for. While the general Roman public was largely unaware of the fact that lead is toxic, a number of well-educated Greek and Roman writers were aware of this fact and even knew some of the symptoms of lead poisoning.

Furthermore, lead poisoning does not seem to have been nearly as widespread in ancient Rome as many people today assume that it was. Lead poisoning was a public health problem and it was probably a lot more common back then than it is today. Nonetheless, contrary to what many people today assume, most people in ancient Rome were not suffering from lead poisoning on a daily basis and lead poisoning probably did not play a significant role in the decline of the Roman Empire.