Bones in 12,000-year-old Cemetery Mirror History of Deadly Lead Production

Lead is increasingly being used in solar panels and batteries, but the more lead we produce, the more people are likely to be absorbing it into their bodies, Hebrew University-led team deduces

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The site of the dig at Palazzo della Cancelleria in Rome, Italy.
The site of the dig at Palazzo della Cancelleria in Rome, Italy.Credit: Michaela Lucci
Ruth Schuster
Ruth Schuster

Increases in lead production in the ancient world correlated with higher amounts of lead in bones, a team from Hebrew University perhaps not shockingly reported Monday, based on analyzing 132 bodies buried in Rome throughout 12,000 years.

The burial ground beneath the courtyard of the Palazzo della Cancelleria in Rome had been in continuous use until the 17th century, the team adds in their paper, published in Environmental Science and Technology. The bodies that were tested for th sconsisted of 127 people from the Roman area and five from Sardinia.

The bottom line is that history, archaeology and these bodies all show that serious lead production began about 5,000 years ago. The dynamics of lead production over the ages is mirrored in the bones.

“Lead pollution in humans has closely followed the rates of lead production,” says Prof. Yigal Erel of the Hebrew University’s Institute of Earth Sciences. “Simply put: the more lead we produce, the more people are likely to be absorbing it into their bodies.”

We add that they tested a bunch of elements and didn’t find similar patterns – zinc, for instance, showed no trend change over time.

Do you breathe?

Before we get to the ancient remains, the team wishes to stress that the problem isn’t confined to the ancient Romans who famously used lead in their pipelines, or medieval nobles in Europe who whitened their faces with the metal.

We now use copious amounts of lead in various products worldwide and lead poisoning is a problem for everybody who breathes, says Erel, who co-authored the paper with Prof. Liran Carmel, Adi Ticher and Ofir Tirosh, as well as University of Vienna’s Ron Pinhasi and Sapienza University of Rome’s Alfredo Coppa.

Indeed, the problem now is presumably worse nearest the areas actually producing lead – which include China and Australia – but the metal is pretty much ubiquitous. Lead has been phased out of paint and is no longer in pipes, which are usually plastic these days. But it’s still there in car batteries and smartphones, to name but two widespread products.

An aerial shot of Palazzo della Cancelleria in Rome, Italy.Credit: Michaela Lucci

“It’s one of the 62 elements in phones,” Erel says. It’s in our earth – and in no small part thanks to its production, it’s in our water and air.

The problem is that lead is a deadly poison. There is no such thing as a “safe” concentration of lead in your food, water or body, the World Health Organization explains. The safe level is zero. How much of a surprise is the study? None in one sense, but it quantifies what we already suspected.

A brief history of lead and poisoning

Lead production actually seems to have begun as much as 8,000 years ago, by hammering raw ore, in Anatolia. Early copper was produced in exactly that way.

But serious production would start about 5,000 years ago in the Bronze Age with the invention of a smelting technique called cupellation. Then there was a leap in lead production, which continued to ramp up in the Iron Age. Then, about 2,500 years ago, coins were invented and lead production faltered.

Palazzo della Cancelleria in Rome, from where 132 bodies were tested for lead poisoning.Credit: Michaela Lucci

This could be explained by the fact that cupellation wasn’t invented to get at lead per se. It was invented to get at silver and gold, with lead being a by-product. Before coins, trading was effected using bits of almost-pure silver.

It is true that the "hacksilber" silver bits were generally broken fragments of bigger things, like jewelry (and were sometimes counterfeited, before the invention of money). But even so, the advent of coinage could have diminished silver production, and hence lead production too.

Civilization around the Mediterranean collapsed around 1,200 years ago, but afterward lead production picked up anew and spiraled to a peak during the Roman Period, when it was widely used – even sometimes in food and makeup, and even though the Romans became aware of its adverse effects.

Separate research reported in 2019 that massive Roman-era lead production contaminated the air in all of Europe, based on ice cores taken from Mont Blanc. Yes, ancient Europeans were rebreathing in lead with their air.

We cannot sneer at the ancient Romans and their vanities. Not fair. We all know perfectly well how bad sugar, gasoline and tobacco are, just to name some of our many and myriad bad habits.

LEAD INVESTIGATORS: Workers excavating the site at Palazzo della Cancelleria in Rome.Credit: Michaela Lucci

Anyway, since lead production picked up properly about 1,000 years ago, its production has just grown more perfected, which isn’t to say more industrially hygienic. And it shows up in the bodies.

Lest you wonder, Israel is not exactly a hotbed of metal production and never was, leaving the biblical-period copper mine at Timna out of it. However, the earliest lead artifact known to date was a 6,000-year-old giant bead found in Ashalim in the Negev Desert. But it had been made in Turkey.

How do we know the history of lead production? Mainly, Erel says, the team relied on previous work by Dorothy Settle (1929-2015) and Clair Patterson (1922-1995), who investigated lead production over millennia. These two, in fact, were behind the modern world taking note that lead is deadly, and behind the discovery that lead contamination in canned tuna is 10,000 times higher than it “should be.”

And now the Hebrew University team and colleagues have directly measured lead exposure in people going back 12,000 years in Italy and found, as predicted, corroboration of that historical timeline. When people produced lead, it got into the environment and others were affected.

According to the Mayo Clinic, even tiny amounts of lead exposure can cause serious health problems. Kids younger than 6 are especially vulnerable because of the potential for mental and physical development problems. “At very high levels, lead poisoning can be fatal,” the clinic warns, noting that potential sources include “contaminated air, water and soil.”

As long as production was relatively small-scale and local, the increase in lead concentrations in bones would be local too. Today, it is not local and the metal is legion. The team notes the roughly 300 percent increase in the demand for lead, nickel, silver and indium for solar panels, and a 1,200 percent increase in the demand for lead, cobalt and nickel for energy storage technologies – i.e., batteries – all in order to “achieve” an increase of "only" 2 degrees Celsius in the global mean temperature. Right now we’re on trajectory for something far worse.

What, lead in solar panels? Yes. While “industrial hygiene” is a thing, there really is no such thing as a free lunch.

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