There has been some scientific speculation as to whether high levels of lead in city pipes caused widespread lead poisoning among Romans, ultimately leading to the decline and fall of the Roman Empire.
The historical record indicates not only that Romans were aware of the potentially injurious effects of lead in the city's sewers, but that they also consumed large amounts of lead as part of their customary lifestyle. Roman author and architect Marcus Vitruvius Pollio, known by the pen-name Vitruvius, wrote a multi-volume work entitled "De Architectura" around the first century B.C., in which he described the features and some of the challenges of Roman civil engineering.
In ancient Rome, lead was readily available and abundant. Because of its malleable properties and low melting point, Lead was seen as ideal for the production of water pipes. While lead was used to line Roman aqueducts, exposure to lead was known to be injurious to human health. As Vetruvius explained, "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."
But lead pipes were not the only sources of lead common in Roman life apparently. In fact, the more probable cause of lead poisoning might have been wine consumption. The naturally sour properties of wine were usually sweetened and cured by mixing pressed wine with a concentrated "mustum," or grape juice boiled down to its essential sugars. The process of creating mustum, as several Roman aristocrats have noted, involved slowly cooking down the juice to syrup in heavy, leaden pots.
In "De Agri Cultura," the roman statesman and philosopher Cato gives directions for reducing mustum 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." Estimates of average wine consumption among the Roman elites vary, but an average consumption of about two liters per day seems a reasonable assumption. Taking into account the lead concentration in mustrum, and the mustrum in processed wine, modern researchers have estimated that Roman elites consumed up to 180 micrograms of lead per day – more than enough to produce symptoms of poisoning.
Whether or not lead poisoning was the deciding fact in the fall of Rome is not really at issue. The important lesson is that the issue of lead poisoning, including both the public health and civil engineering realms, has been well-documented. Lead poisoning from lead used in construction was a well-recognized challenge to Roman builders. They understood the tradeoffs and risks in much the same way that a modern civil engineer might. While Roman builders were not unaware or unconcerned about the fact that lead is a poison, they were also very intelligent about the chemistry involved. As it turned out, the acidity in rain water reacted with the hydrogen in the lead pipes to produce a "calcium carbonate." This alkaline layer grew over time to up a third of the lead pipes' diameter, thus forming a protective shield against lead leeching into pipes.
That's why modern experiments that test the concentration of lead in the remains of ancient Roman aqueducts may not tell the entire story. The fact that ancient historians, builders and statesmen wrote specifically about lead's advantages and pitfalls should also inform the modern debate over civil infrastructure development. When cities like Flint, Michigan, are exposed to lead, not because of the lead in the pipes themselves, but in fact because of a simple engineering mistake, there is a problem. It is not as problem of technical knowledge or engineering skill. It is a matter of leadership.
The reason why lead poisoning is associated with the decline of the Roman Empire has very little to do with lead poisoning per se. The decline of the empire was associated with the decline of public infrastructure in general. If the state was not able to afford to protect the citizenry from lead poisoning, how capable could the leaders be? If the state is resorting to money-saving measures that prolong basic maintenance, what kind of trade-offs is it making?
These core questions are relevant to our times too. We have stretched our productive capacity in America to the breaking point without retooling. Pre-designed through-put for almost every major conduit – whether we are talking about the electrical grid, the sewer systems, bridges, damns, or military hardware – has exceeded original estimates. We have a wonderful opportunity to rebuild America. Rebuilding our infrastructure will not only provide jobs, but renew our civic spirit.
The ancients knew something about the political importance of being able to solving big problems. One of the major effects is that it can help unify the national will and put citizens and government on the same side. The potential for a national rebuilding project that restores American infrastructure is also an intensely practical pursuit. Expanding, replacing and rebuilding will provide the structures for a new peacetime American industrial renaissance.
Media wishing to interview Armstrong Williams, please contact [email protected].
|