The Disturbingly Long History of Lead Toxicity in Winemaking

Ancient Roman fresco
Photo by Louis Mazzatenta, Alamy

In recent years, wine has been touted as rich in antioxidants and healthy for your heart. These claims, though questionable, are in stark contrast to wines of yore that had a slightly more deadly kick. One common wine ingredient drove unwitting imbibers into a slow decline, that sometimes even resulted in death: lead.

The highly toxic element was, for millennia, included frequently in winemaking and storage. The metal was used as a sweetener and preservative, as well as for its ability to impart brilliant clarity to glassware. Its role in wine history dates to at least 2000 B.C., and even extends to today.

Sweet, sweet ancient wine

In ancient Rome, the upper class favored wine sweetened with sapa, a syrup made by boiling down grape juice in leaded vessels. When heated, toxins leached into the syrup, which was then combined with fermented juice to tame unpleasant tannins and bacteria, as well as act as a preservative.

“The role of manufacturing sugar lead goes all the way back to the Greeks, but the Romans popularized it,” says Dr. Jerome Nriagu, Ph.D., DSc, emeritus professor at the University of Michigan. He’s also the author of Lead and Lead Poisoning in Antiquity (Wiley, 1983). “There are many records of essentially [Roman] doctors describing very precisely the symptoms of acute lead poisoning.”

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One study speculates that Roman wine contained as much as 20 milligrams of lead per liter. Over time, the researchers said it would cause a “decrease in fertility and increase in psychosis among the Roman aristocracy….”

Lead was also suspected to have been used in Egyptian winemaking vessels. The soft metal had the ability to be easily molded and shaped.

“There are Egyptian drawings of a large concave dish [used to] evaporate water out of grape juice,” says Dr. Andrew Waterhouse, Ph.D., wine chemist and professor of enology at University of California, Davis. This juice with a higher concentration of sugar was then fermented.

“It was one of the few metals [Romans and Egyptians] had that they could work,” he says. “Iron was really much, much harder to work. Unfortunately for them, the lead was toxic, and they didn’t know it.”

Amenhotep II offering two glasses of wine to a god / Photo by Debra Angel, Alamy
Statue of Pharaoh Amenhotep II offering wine to a god / Photo by Debra Angel, Alamy

Thanks to its use in everything from plumbing and ceramics to cosmetics, pinpointing lead exposure as the cause of symptoms was tricky. Ancient Romans referred to paralysis and other physical and neurological problems they experienced as colic Pictonum.

Inklings of toxicity

Greek physician Nikander suspected as early as 200 B.C. that lead might cause such symptoms. In ancient Rome, its toxicity was suspected to a degree, particularly in intentional poisonings. However, its use in wine and elsewhere persisted.

Similarly, in medieval Europe, ingesting the metal was difficult to avoid. It was common in pewter drinking vessels, which leached toxins into wine and other beverages, says Nriagu.

Colic outbreaks like those experienced during the Roman Empire continued to plague Europe for centuries, as lead sugars remained a popular way to sweeten wines and balance tannins.

“The connexion [sic] between the disease and prevailing methods for ‘correcting’ wines was drawn in 1696 by Eberhard Gockel, then the city physician of Ulm,” reads a study abstract by Josef Eisinger, professor emeritus at the Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, New York.

Gockel made this discovery after one such outbreak, which prompted Duke Ludwig of Württemberg to ban the use of lead in wine, under penalty of death.

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Elsewhere, colic outbreaks continued, like in Devonshire in the early 1700s, caused by lead acetate-sweetened cider. In 1767, Sir George Baker connected the outbreak to lead found in cider presses and the weights used to sweeten the cider.

In 2010, a discovery of Champagne bottles from a 19th-century shipwreck in the Baltic Sea revealed the presence of lead in those wines. A study of the find revealed high amounts of lead remained in the bottle’s contents, even after being lost at sea for 170 years.

Last month, test results of glass fragments from the 8th and 9th centuries discovered at a dig site in Cordoba, Spain, were published in Proceedings of the National Academy of Sciences. It found that the more recently produced fragments contained high amounts of lead, indicating that Spain may have been the first to produce lead glass.

Vintage Italian wine crystal glasses / Photo by Riccardo Bianchini, Alamy
Vintage Italian wine crystal glasses / Photo by Riccardo Bianchini, Alamy

Going crystal clear

Around the mid-17th century, the advent of crystal glassware by businessman George Ravenscroft ensured lead’s continued contact with wine.

“Ravenscroft experimented with the idea of adding lead oxide to the glass,” says James Shackelford, professor of chemical engineering and materials science at University of California, Davis and co-author of The Glass of Wine. “He had lived in Venice for a while, which was a hub for state-of-the-art glassmaking in the 17th century. Back in England…he added a significant amount of lead oxide. That makes the glass melt a bit easier, but the big benefit was that made it clearer.” Crystal clear, in fact.

The discovery was monumental. Ravenscroft became the first to produce ultraclear glassware in England (though he was far from the first to add lead to glass). Because it was easier to work with, he could shape it into intricate designs.

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“That transparency became very attractive,” says Shackelford. “It’s an optics thing. What lead oxide does beyond make it easier to melt…is that lead is high on the periodic table, so it has a high index of refraction.”

Ravenscroft referred to this leaded crystal as “flint glass,” as it was made from a base of calcine flint. He secured a seven-year patent for his process from King Charles II in 1674. However, his glass-making venture only lasted until 1679, and he died in 1683.

By the end of the century, other large-scale glass manufacturers had begun to produce glass in this fashion. Shackelford says that this process eventually allowed Claus and Georg Riedel to manufacture their brilliant, ultrathin and far more affordable glassware in the 1980s.

Riedel phased out the production and sale of leaded glassware in 2015, though other wine glass manufacturers continue its use. Lead products are required to contain at least 24% lead, according to U.K. regulation.

“It does raise the obvious question around safety,” says Shackelford. “The general thought from public health [officials] now is that the lead oxide that’s in the lead crystal and some other glass products is chemically bound up. It’s not going to leach into wine [after short periods of time].”

A display of cosmetics containing lead, in 1934
Cosmetics containing lead in 1934 / Photo courtesy Harris & Ewing photograph collection, Library of Congress

Lead lives on

As the hosts of This Podcast Will Kill You point out, at the turn of the 20th century, the lead industry campaigned for the material’s widespread use in everything from children’s toys to paint and telephones. They aimed to drown out science that pointed to lead’s deadly effects.

It wasn’t until 1978, around the time that Riedel began to manufacture its wine-enhancing crystal glassware, that the U.S. banned lead paint and pipes.

Lead was present in wine capsules into the early 1990s, when a lawsuit required wineries to issue warnings about lead content in their foil toppers. In 1996, the FDA issued an amendment to its regulations that prohibited “tin-coated lead foil” because they may, “as a result of their intended use, become a component of the wine.”

Despite widespread knowledge of its toxicity, lead continues to pose a risk. In Flint, Michigan, lead-contaminated drinking water flows from the taps. Nriagu says this affects largely low-income and marginalized communities.

“The lead pipes [were] actually found in the more prestigious and expensive homes [of these cities],” says Nriagu. “But then over time as these cities decay, and the rich people move out of the older parts of the city, low-income Blacks move in. They’ve inherited the problem.”

Research reveals that this is a widespread issue. But lead exposure also comes in many, often more subtle, forms.

2018 study found high levels of “migratable lead” on decorated drinking glassware. In 2019, another revealed the metal in glass bottles used to package beer, wine and spirits. While levels found in the glass were deemed to be of “low significance,” enamel bottle decorations contained far greater quantities that could be hazardous. The author of the 2019 study writes that this is “further evidence of harmful elements being unnecessarily used where there are alternatives available.”

The World Health Organization issued a similarly blunt warning: “There is no level of exposure to lead that is known to be without harmful effects.”

Antique glass decanter with ornate pewter lid / Photo by Gary Perkin, Alamy
Antique glass decanter with ornate pewter lid / Photo by Gary Perkin, Alamy

What can you do?

We’ve come a long way since the Romans added lead sugar freely to wine, but you can still avoid potentially dangerous products that may already be in your home.

Lead capsules are no longer used, but “there are some bottles out there that might be from [1991 or earlier] that still have lead on them,” says Waterhouse. If you have a collection that dates back this far, keep an eye out for white residue on the bottle’s neck. It could indicate a leak and a potentially dangerous reaction.

“[If it had been] sitting there for years [with a leak], it would make a lead tartrate because of the tartaric acid in the wine,” he says. An easy solution? “You can easily get rid of it if you just take a damp rag and wipe it off.”

Also, be aware of what glassware in your possession may contain lead, namely crystal decanters. It could leach lead into wines when stored over long periods of time, as Port often is. Shorter contact time, which is more common for crystal decanter and glassware usage for typical wine consumption, is much less of a concern as there’s little opportunity for leaching.

“I couldn’t possibly recommend keeping anything in a leaded crystal container for an extended period, but just drinking from leaded crystal glasses is not really a problem,” says Waterhouse. “I tell students in my classes that if their wine-crazy uncle offers them a drink of a Port from his favorite crystal decanter, politely decline.”

Published on July 20, 2020
Topics: Wine History