Lead is useful, surprising, unpredictable, dangerous – and deadly. Previous generations found it to be an essential part of civilized living: pipes, pewter, pottery, paints, and even potions were made with it.
The Roman architect and engineer Marcus Vitruvius, who lived in the first century AD, observed that labourers in lead smelters always had pale complexions. The Greek physician Hippocrates described a severe attack of colic in a patient who was a lead miner. Neither attributed the cause to lead, and nor did most of the physicians who down the centuries treated patients affected by it, although there were times when a few doctors realized how toxic it could be.
The Ancient Greek poet and physician Nicander described the symptoms of lead poisoning, including hallucinations and paralysis, and recommended strong laxative treatments to cure it. Yet lead continued to poison unchecked, largely because the link between the metal and its adverse effects on health was not obvious. On the other hand its benefits were obvious, indeed the more lead was used in a society, the higher the standard of living of its citizens. Lead can be an extremely useful metal because it is easy to win it from its ores, it melts at a relatively low temperature, and it makes an ideal solder. Lead is easily worked and can be hammered into sheets, and used to make pipes, pans, roofing, and cisterns, and it is impervious to attack by the oxygen of the air and by water.
Lead has been mined for more than 6000 years, and it was certainly known to the Ancient Egyptians who used lead pigments as well as casting the metal itself into small figurines. Cosmetics made from lead ores have been found in tombs of the second millennium BC, and these consisted of black galena (lead sulphide), white cerussite (lead carbonate), white laurionite (lead chloride), and brown phosgenite (mixed lead chloride carbonate).
The Egyptians may have got some of their lead from Phoenician traders who were mining lead in Spain about 2000 BC, but it was the ancient Greeks who really began producing lead on a large scale, inadvertently as it happened, because they were really mining for silver. From 650 to 350 BC the Athenians exploited a large deposit at Laurion from which they eventually extracted 7000 tonnes of silver – and more than 2 million tonnes of lead.
The silver from Laurion underpinned Athens’ economic power, until the mines became played out in the fourth century BC, after which Athens declined. By then more than 2000 pits had been dug and 150 km of galleries excavated. The waste lead from these mines was still being exploited hundreds of years later by the Romans, who found more and more uses for the metal and its compounds. Builders, plumbers, painters, cooks, potters, metal-workers, coin-makers, dentists, vintners, and undertakers all made use of it.
The Ancients saw lead as a god-given benefit and in Egypt it was associated with the god Osiris, while the Greeks linked it to Chronos, and the Romans to Saturn, which is why lead poisoning is still sometimes called saturnism. In reality lead was really a metal sent from hell. A puzzling feature of the Roman Empire was the surprisingly low birth rate of its ruling classes, and this too has been linked to the high level of lead in the diet. If the fate of a ruling class is what determines the fate of an empire, then the theory that one of the greatest of all empires was destroyed by lead may not be so fanciful as it first sounds. In fact more than just the aristocracy appears to have been less than reproductive.
The Empire’s population remained stable at around 50 million, despite such social benefits as adequate food supply, high standards of hygiene, and the growth of science, technology, and medicine, all of which should have led to an increase. Some researchers have put forward the theory that lead was to blame, and we know from the analysis of the bones of its citizens, that their use of this metal was undermining their health. The theory that lead led to the decline of the Roman Empire was first advanced in 1965 in the Journal of Occupational Medicine by S. C. Gilfillan of Santa Monica, California, and his arguments were subsequently reinforced by Jerome Nriagu of the National Water Research Institute of Canada. Nriagu, writing in the New England Journal of Medicine (Vol. 308, p. 660, 1983), estimated that a typical aristocrat would be absorbing 250 μg/day, while ordinary Roman citizens would get around 35 and slaves only 15, most of which would come from wine in the case of the first two groups. Nriagu has even linked the medical complaints and bizarre behaviour of the Roman emperors to their high lead intake. Many of them suffered from gout as a result. Claudius who reigned from 41 to 54 displayed many of the symptoms of lead poisoning, including recurrent attacks of colic. Nriagu expanded on the theory in a scholarly but controversial book, Lead and Lead Poisoning in Antiquity, published in 1983.
Lead contaminated the homes of Romans in many different ways. Drinking water was transported along lead-lined aqueducts, through lead pipes, stored in lead cisterns, and maybe drunk from lead pewter vessels. The walls and woodwork of rooms were painted with lead-based paints. But one item in particular must have contributed to the lead in their diet, and that was a sweetening agent known as sapa. The famous Roman writer Pliny (23-79) gives the recipe for making sapa and specifically mentions that it must be made in lead pans. Roman cooks had only two sweetening agents that they could use for desserts: honey and sapa. (Sugar was unknown to the Romans. Sugar cane was originally to be found only in Polynesia, and gradually spread westwards reaching Europe about 800). Sapa was made by boiling down unwanted or sour wine in lead pans and we now know that the syrup so produced tasted sweet because it contained a lot of lead acetate.
The lead came from the pan in which it was prepared, the acetate came from the wine that was being made sour by the action of enzymes and air which can convert alcohol to acetic acid. The crystals that form from such syrup looked and tasted like the sugar we know today, and were eventually to be known as sugar of lead.
Old recipes for making sapa have been repeated in recent times, and analyzed, showing that the syrup contained around 1000 ppm of lead (0.1%). A spoonful of sapa would deliver a dose of lead that would undoubtedly lead to some of the symptoms of poisoning. Yet the popular Roman book, The Apician Cookbook, had sapa as an ingredient in 85 of its 450 recipes, and sapa was used by vintners as well.
Sapa was used to preserve wine, and especially Greek wines. These were popular in Rome but had a reputation for causing sterility, miscarriages, constipation, headaches, and insomnia – all of which would be true if they had been doctored with sapa. Roman prostitutes were reputed to eat sapa by the spoonful because it acted as a contraceptive, gave them attractive pale complexions (due to anaemia), and would cause abortions.
The Romans mined lead in Greece, Spain, Britain, and Sardinia. At the height of the Empire the British deposits were the main source of supply and the annual rate of lead production was in excess of 100 000 tonnes/year. (In total, the Romans are estimated to have mined and used more than 20 million tonnes of lead.) Originally the Romans left the mining and refining in private hands, but ultimately it was deemed so important that it was all state-controlled. The Romans were not unaware of the risks of lead mining so it was done mainly by slaves, and at the height of the Empire 40 000 slaves worked the mines of Spain.
The collapse of the Western Roman Empire brought an end to economic development in Europe for almost 1000 years. The causes of the Fall of Rome were a combination of climate change, plague, economic decline, religious dissent, power politics, and outside pressures. Indeed from 250 onwards, all these factors came into play. As the Earth’s climate became colder, northern peoples began to move southwards and invade. Plague appeared and epidemics ravaged the Empire. Meanwhile internal military and religious disputes raged on. Lead was at most a minor factor in Rome’s downfall.
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