Lead is an unpredictable poison, but it may have brought down the most powerful wine-drinking empires the world has seen.

Roman George IIIThe Fall of Empires
The gradual poisoning of the ruling classes in ancient Rome with lead may have caused the downfall of their Empire. Did the British Empire suffer the same fate?

When the Empire struck lead

John Emsley

Published: 25 December 1986 – 1 January 1987

An historian of the ancient art of making wine, Sir Edward Barry, wrote a book in 1775 called Observations Historical, Critical and Medicinal and the Wines of the Ancients. In it, he commented on the Roman habit of adding boiled-down syrups to their wines to improve the flavour. These sweet additives contained a large proportion of dissolved lead salts.

Indeed, the Romans used so much lead in their homes and kitchens that they must have suffered from its toxic effects. The archaeological evidence, in the form of bone analysis, supports this. Bone is very good at trapping lead that enters the body.

The Roman ruling classes were most at risk from lead poisoning because they relied on lead for many everyday items such as pewter, paint, pans and pipes, that the less wealthy could not afford. In 1965, in the Journal of Occupational Medicine, S. C. Gilfillan of Santa Monica, California, first put forward the idea that lead was a significant factor in the fall of the Roman Empire.

Jerome Nriagu of the National Water Research Institute of Canada has strengthened Gilfillan's case in the past 20 years. His fascinating Lead and Lead Poisoning in Antiquity gives a complete review of the role of this insidious metal in earlier civilisations.

If we accept that lead was instrumental in destroying the Roman Empire then we must face the possibility that it also played a role in the downfall of the British Empire. The British too relied heavily on this metal for domestic comforts, such as piping, pewter, pottery, paints and port wine. One of the puzzling features of the British Empire in the 18th century was the vigour of its industrial revolution and the idiocy of its ruling classes.

And while the one created wealth and made possible the expansion of the Empire, the other managed to lose the most important colony of all, America. Had the Empire not split in this fatal way it might be flourishing still, and although the British were still to triumph in the 19th century and produce the world's greatest empire, within two generations it had collapsed. But that is a different story. We must look at what went wrong at the beginning, and to do that we must first look at the problem of lead in ancient Rome.

The symptoms of slow lead poisoning are very varied but include colic (stomach cramps), constipation, loss of muscular energy, headaches and gout. Gout was once a common complaint of the upper and middle classes of both Rome and Britain. Both blamed it on too much rich food and wine; they may have been right. The Roman writers Seneca, Virgil, Juvenal and Ovid all poked fun at the sufferers of gout in their day and the cartoonists of 18th and l9th century London treated it with much mirth. The popular attitude to the disease was that it was divine retribution for gluttony. But what caused the build-up of uric acid and guanine in the body that eventually leads to this painful condition of the joints? According to Jerome Nriagu it was caused by lead damaging the kidneys. There is no doubt where much of the lead the Romans received came from, especially if they had a taste for sweet foods. The Romans boiled down grape syrup, known as sapa, or boiled down the juice of other fruits, known as defrutum, in lead pans. The pans had to be made of lead to make the food very sweet. The acids in the wine reacted with the lead to produce soluble lead salts, such as lead acetate, which is as sweet as sugar. The common name for lead acetate in fact was 'sugar of lead'.

Box. How the body can absorb lead

How much lead the body absorbs depends on where we live and the food we eat. People who eat a lot of canned food and live in old houses near busy roads in industrial cities run the highest risk of lead poisoning and may take in up to 0.5 milligrams per day. Those who eat fresh food and live in post-war houses on the outskirts of small rural towns are least exposed to the metal and may ingest only 0.1 milligrams per day. Whatever the amount consumed, very little lead actually enters the blood stream because the wall of the gut is an effective barrier to lead. Ann Morton at Aston University uses the short-lived radioactive isotope 203Pb, with a half life of 52 hours, to discover the way the body absorbs lead. Her work shows that the body absorbs only three per cent of lead passing through the gut, and that protection comes chiefly from the other constituents of the diet. Taken on an empty stomach, 60 per cent of lead in the diet enters the blood stream.

ln its journey across the wall of the small intestine, the lead needs first to dissolve, and certain constituents in the diet, such as vitamin C and some amino acids, may help the process. Chemicals in food, especially phosphates, hinder this by forming insoluble lead phosphates. Up to 10 per cent of the lead may bind itself to the wall of the intestine, and goes no further.

The lead in solution may move across the membranes of the cells of the gut's wall, but lead passes into the body through the junctions between the cells. These pores are permeable to metal ions and specifically designed to let them through, It is because lead, as the ion Pb2+, is chemically similar to calcium, Ca2+, and other essential metal ions that some lead slips by. Even though lead may breach the first line of the body's defences against it, the metal still has two other obstacles to overcome before it can do its damage. First, the kidneys can recognise it as a foreign body and filter some of it out of the blood. Secondly, lead may come out of solution in the bones, which are very rich in phosphate. Most of the lead ends up in this sink, and indeed our skeletons trap so much lead that we can eventually carry a fatal dose of the metal locked up in our bones. Typically, we marry about 200 milligrams of lead in this way. How securely held this is depends upon other factors. Any deterioration of our bones may begin to release the lead, something which can happen in old age or during certain illnesses.

Old recipes for making sapa produce a syrup that has over 1000 parts per million (ppm) of dissolved lead. In the natural state, the level of lead in the environment and living things is about 0.001 ppm. Sapa or defrutum is mentioned in 85 of the 450 recipes of the classic work The Apician Cookbook, the Roman equivalent of Mrs Beeton's Household Management.

Curiously this lady makes the observation in her tome that 'lead is by no means an active poison, although it is popularly considered to be so'. However, she goes on to describe treatments for dealing with it, mainly laxatives and enemas. That was in 1859.

What all empire builders seem to have had was a prodigious appetite for wines. The average Roman drank over a litre a day, much of it improved with added sapa. The vintners' trick of adding litharge (lead monoxide) to wines was still common in the 18th and 19th centuries, albeit at much lower levels. The British were partial to port wine, and for example imported over 20 million litres of it in 1825. Bottles of this age have been analysed and show lead levels of over 1 ppm. However, this was probably not the only danger – drinking it from a pewter tankard or a pottery mug could have added even more lead, as both were made of materials composed of high levels of lead. The Table compares the many ways in which lead could find its way into Romans and Britons, either deliberately or accidentally.

Table: Deliberate and accidental sources of lead in imperial diets
Roman EmpireBritish Empire
Drinking water lead-lined viaducts, lead storage tanks lead piping, lead storage tanks
Tableware lead pewter lead pewter, lead-glazed pottery
Kitchenware lead-lined pans, lead solder
Food high-lead-syrups, (sapa and defructum), used to sweeten wine and in cooking leaded wines, lead solder on canned food
Paint white lead white lead, chrome yellow (lead chromate)
Medicinal uses lead plasters lead medicines for TB, VD, haemorrhages and diarrhoea
Cosmetics black lead oxide eye-liner lead acetate hair dye

Outbreaks of chronic lead poisoning from alcoholic drinks occurred frequently from the 16th century onwards. A notable epidemic of colic occurred in Poitiers in 1572 – called Picton colic – and 'dry gripes' was an affliction of rum drinkers of the West Indies and Massachusetts in the 17th century. People sometimes made the connection between colic and lead poisoning. In Germany, the authorities linked colic to the use of litharge to sweeten wines, and so they made the habit a capital crime. Meanwhile in Britain, one popular book of the 17th century actually recommended litharge as a way of improving homemade wines.

The best known outbreak of colic afflicted hundreds of people in the West Country in the 18th century, and became known as Devon Colic. Many of the victims suffered from advanced forms of the disease which produced such alarming symptoms as paralysis, madness, blindness and even death. Devon Colic was first reported in 1703 and was, almost from the start, associated with drinking cider. Yet it was difficult to pin the blame on this drink because the disease was endemic only to the West Country and not found in Herefordshire, the other big cider-drinking area. However, cider was the cause, or rather the lead dissolved in it. Contamination in Devon was not deliberate but accidental. Local outbreaks were linked to the use of presses and fermentation vats lined with lead or lead pipes. The habit of using lead for these purposes was often a local custom, which explained why one village would be afflicted with the colic while a nearby village had no cases of the disease.

In 1767, the Queen`s physician, George Baker, proved that lead was the culprit and actually extracted a grain of lead (65 milligrams) from three gallons (13.6 litres) of cider, which represents about 5 ppm. Even at one pint a day, such cider would easily produce chronic lead poisoning. Some farm labourers in Devon used to drink a gallon a day and must have suffered as a result.

Baker publicised his finding in articles and lectures, and went on to condemn lead in general. He even blamed lead for the well-known occupational illnesses affecting plumbers and painters. Sickly children, he thought, may be victims of the metal, having perhaps chewed toys covered in lead paint. Yet, by and large, Baker's foresight was ignored. Early this century a survey of painters revealed that nearly half of them were suffering some form of lead poisoning. Baker was a prophet before his time.

Lead poisoning is generally so mild that it can go unrecognised. In Baker's day, in fact, several lead compounds were actually part of the medical pharmacopoeia. Doctors used a mixture of white lead and sulphur to treat tuberculosis; they also gave lead acetate with opium to stop diarrhoea (the lead paralyzed the intestines, the opium deadened the pain of the colic). Doctors of the day also prescribed lead acetate to control internal bleeding and gonorrhoea. Little wonder that many people looked upon lead as beneficial, not detrimental.

Roman physicians also used lead. Menecrates, the chief doctor of the emperor Tiberius (AD 14–37), had invented a plaster for skin complaints. This was a mixture of lead oxide and linseed oil plus other herbal extracts and was called diachylon plaster. It was effective in the treatment of spots, sores and skin infections for nearly 2000 years. These plasters were still on sale in Birmingham in the 1890s when a scandal arose because of their use in procuring abortions. Women were scraping off the ointment and eating it to induce miscarriages.

Throughout the 18th century and well into the Victorian age, lead was everywhere in the home. Slowly, it came under suspicion. The women whose job it was to apply lead glaze to pottery suffered not only colic but paralysis and blindness, and were also prone to miscarriages. Conditions in the industry did not begin to improve until the 1890s, when trade unions fought a vigorous campaign. Gradually, lead was removed from pewter, pottery glazes and paints.

Since 1930, the chief whitening agent in paint has been titanium dioxide, not white lead, which is a lead carbonate hydroxide, 2PbCO3.Pb(OH)2. Lead piping lingered longer. Even in the pre-war housing boom of the 1930s, builders thought lead piping was safe if the water was hard. Today, the home is virtually lead-free. The one exception is the solder used in tin cans, although can manufacturers have replaced lead with silver in tins containing baby foods. Even the notorious leaded petrol is on its way out. Beginning this year lead in the air we breathe has finally started to diminish. Soon the only danger we will face will be the lead we have stored in our bones, but even there we carry a much smaller burden than previous generations.

The lead in children's bones is now below a level of 2 ppm, and in most adults is only about 5 ppm. Analysis of the bones of skeletons found in Polish crypts, where they have been stored for centuries in dry conditions, unaffected by the lead in soil, shows that some individuals had over 100 ppm. The skeletons of people who had lived in the 18th century averaged 48 ppm. In the 19th century, people had an average of 60 ppm of lead in their bones. As it was in Poland, so it must have been in the more advanced society of industrial Britain.

One wonders how many of those peculiar conditions of that period, those weak constitutions, the sickly children, the endless preoccupation with nervous debility and patent medicines, was really all to do with undiagnosed lead poisoning.

Curiously, in both Rome and London the higher up the social ladder people were, the greater the danger from contact with goods containing lead. Consequently the ruling classes were most at risk of lead poisoning and this is seen as one of the explanations for the eccentric behaviour of many of the Roman emperors whose names became synonymous with unbridled sexual depravity and political corruption. The British ruling classes of the 18th century were also noted for their decadence and eccentricity: the era was called the age of scandal. At the pinnacle of that society was King George III (1760–1820). He suffered from several illnesses that were sometimes complicated with mental disturbances.

These occurred frequently between 1762 and 1812. The final bout of illness left him blind and insane, and his even more eccentric son, George, became Prince Regent. Historians have made several attempts to diagnose George III's complaint, and the clue giving some insight into the King's condition was the symptom of red urine. This is a sign of the faulty metabolism of a pigment porphyrin. Porphyrins are needed for the synthesis of the red pigment in blood – haemoglobin – among other things. Porphyrins are made from simpler chemicals, such as delta-aminolevulinic acid or ALA for short. ALA is converted to porphyrin in a series of chemical reactions. Lead can block the synthesis of porphyrins leading to a build-up of ALA, by poisoning the enzymes necessary for the chemical reactions to occur. A build up of ALA produces symptoms such as colic, constipation, loss of muscular energy, and mental symptoms that start with headaches and progress to insomnia, irritability, delirium, madness and blindness. George Ill suffered from all of them.

In 1849 a bag of lead acetate, weighing 30 pounds (13.6 kilograms), was accidentally mixed with 80 sacks of flour and baked into bread. Five hundred people were affected, some of them seriously, but none fatally. Many of the victims has symptoms similar to those of George Ill, such as red urine.

Medical writers such as Ida Macalpine and Richard Hunter have plumped for an inheritance of defective genes as the cause of George IIl's porphyria. They have even looked for other members of the blood Royal who have displayed signs of the hereditary defect that causes this. Porphyria is caused by an over-production of ALA and porphyrins. More likely George, the Mad King from whom the American colonists were happy to be free, was really suffering from a surfeit of ALA caused by lead poisoning.

Lemonade and Sauerkraut

It seems unlikely that George lll's enemies deliberately fed him a large dose of lead as a means of assassinating him. Lead is not toxic enough to be a reliable poison. However, there are two ways in which poisoning may have happened accidentally. The King was very fond of lemonade and sauerkraut and both of these could have given him lead poisoning. lf lemonade is made in lead-glazed crockery, the citric acid in the fruit juice can dissolve enough lead from the glaze to produce dangerously high levels of lead in the drink.

Sauerkraut is also capable of dissolving lead from the vessel in which it is made. Lead poisoning was common in Germany in the Spring of each year, when the peasants ate their sauerkraut. Since sauerkraut was not a common dish in Britain in the 18th century, George III may well have been the only member of the Royal household who ate it, and consequently the only one to suffer the consequences. lt is still possible to prove or disprove the theory that lead caused George's condition. An analysis of his remains, buried at Windsor Castle, is still possible and should reveal levels of lead far in excess of the 'normal' 5 ppm. lf his illness was due to lead poisoning then we might expect to find 50 ppm or more of this metal in his skeleton. It is unlikely that the Royal Family would permit chemists to analyse George's bones, however.

Whether lead was really responsible for the decline and fall of the Roman Empire will always remain contentious. Nevertheless, whatever we say to the Romans applies equally to the British Empire during most of its history. From 1700 to 1900 there was too much lead in the diet. It is a moot point whether the rulers of the world's greatest Empire might have made wiser decisions and preserved that incredible institution if their grey matter had not been clouded by this grey metal. Or does it need a little bit of lead to cause that mild insanity that make a culture believe that it has a divine right to rule?