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When Color Kills: Toxic Pigments Through the Ages

July 15, 2019

Napoleon Bonaparte: revolutionary military commander, first Emperor of France, and champion of widely influential civil codes.

 

Vincent Van Gogh: Dutch oil painter of starry nights and sunflowers, post-Impressionist idol, self-mutilating psychiatric patient. 

 

What did these two men — born in different centuries — have in common? 

 

According to historians, they were both likely poisoned by pigments. 

 

After being exiled to a remote island in the Atlantic Ocean, Napoleon’s health quickly faded, and ultimately he succumbed to stomach cancer. But the cause of death is not so simple. Many believe that his cancer could be attributed, at least in part, to his wallpaper. The ornate floral patterns adorning the walls of Longwood House were painted with a pigment known as Scheele’s green. This pigment is now obsolete. The reason? When exposed to prolonged humidity — as was certainly the case in a washroom on a tropical island, where Napoleon reportedly soaked in long, luxurious baths — a type of mold can develop. This process results in the release of arsenic gas, which we now know is extremely carcinogenic.

 

Indeed, in the 20th century, long after his death, toxicology tests were conducted on Napoleon’s hair. As you might have guessed by now, high levels of arsenic were found in his follicles.

 

For his part, Van Gogh has long been revered as a brilliant, yet mad artistic genius; that madness, however,  may have had something to do with the lead in his paint. His “impasto technique, based on thick layers of paint,” meant that he used “colors with a high content of lead, such as white lead (lead carbonate) or chrome yellow (lead chromate), in the mixtures he prepared.” He also apparently had a tendency to lick his brushes, which could have led to the ingestion of these paints. Lead poisoning can lead to a whole host of symptoms, which were, incidentally, similar to those exhibited by Van Gogh—including anemia, abdominal pain, and seizures.

 

Though they have different effects and are derived from different sources, arsenic and lead are similar in that they’re both heavy metals. Actually, many pigments from throughout the ages have contained various types of heavy metals in different amounts, and with differing levels of toxicity. 

 

First, we should point out that “heavy metals” is a tricky term to pin down: they’re “an ill-defined subset of elements that exhibit metallic properties.” Not all heavy metals are dangerous and, in fact, some are necessary for survival, such as iron and zinc. The trouble is, heavy metals bioaccumulate; this means there’s “an increase in the concentration of a chemical in a biological organism over time.” If Napoleon had just been exposed to the green wallpaper a handful of times, or if Van Gogh only occasionally used lead paint, it’s possible they would have been fine. 

 

 

Besides these two examples, other historical pigments had plenty of their own heavy metal problems. Orpiment, or King’s yellow, can be found on ancient Egyptian papyrus scrolls. The chemical name for this pigment is arsenic sulfide. As you might imagine, this means the fumes were both poisonous and — owing to the sulfuric component — very stinky

 

Yellow pigments in general seem to have been notoriously riddled with safety hazards. For instance, Frank Cyr (1900 — 1995), an American educator, unveiled a plan to make all school buses uniform and easy to see, rain or shine—hence the bright yellow we associate with school buses. However, the first pigment used on these buses, which “came to be known as ‘National School Bus Chrome,’” contained a particularly noxious type of chromium. This hexavalent chromium is essentially “hungry for electrons and will actually damage DNA trying to get it.” 

 

Likewise, uranium — one of the heaviest metals — gives “uranium yellow” its hue. It also gave users of the pigment radiation poisoning. Until the second half of the 20th century, it was used “to tint glass and ceramics in shades ranging from yellow-green to orange and red,” but it dates all the way back to 79 A.D. Italy. Apparently, during the war efforts for WWI and WWII, the “pigment was used for detailed painting on military vehicles; young women tasked with the work often rolled their brushes between their lips to create a fine point, unknowingly exposing themselves to dangerous levels of radiation.”

 

 

Historically, the track record of red pigments has been scarcely better. Vermilion was used for millennia, from ancient China to Renaissance Europe. It was derived from mining cinnabar, “the ore of which contains mercury” and which cost miners “their lives due to the toxicity of the substance.” Eventually, vermilion was replaced by cadmium red, but in recent decades this alternative has also come under fire. Though still allowed in paints, the European Union has banned the use of cadmium in certain items, and the EPA’s Office of Resource Conservation and Recovery added it to a list of chemicals “targeted for elimination, reduction, or substitution because of their toxicity and their tendency to accumulate in the body.”

 

These efforts make sense, as cadmium exposure is linked to renal dysfunction, lung disease, lung cancer, and bone defects. In 2010, Miley Cyrus’ jewelry line was pulled from WalMart because of unsafe levels of the heavy metal. That same year, Claire’s recalled 19,000 friendship bracelets for the same reason. But many companies, like Winsor & Newton, still market paints made with cadmium red pigments, claiming the levels aren’t high enough to exert a toxic effect. 

 

Though most of the worst heavy metal offenders have been phased out of the world of pigments, if you peruse the aisles of an arts and crafts store, you will find that some products contain warning labels. This is thanks to the Labeling of Hazardous Art Materials Act of 1988, which requires “arts and crafts materials manufacturers to identify product ingredients that are known chronic hazards on the label with appropriate hazard warnings,” as well as “provide safety data sheets for these products that offer detailed information on potential health risks, first aid measures, flammability,” and more. 

 

But even if you still see paints labeled “Cadmium Red” or “Lead White,” these are often actually hues rather than the historic, true pigment. In this context, a hue refers to “a color that is made up of different pigments than the original,” precisely because of the pigment’s toxicity, or because of its unavailability. 

 

Still, it’s hard to say if this new generation of hue alternatives is decidedly safer than the heavy metal pigments of yesteryear. Monona Rossol, who runs a nonprofit devoted to arts safety, said of naphthol red in place of cadmium: 

 

“We know what happens in two weeks after animals ingest it, but we don’t know much else. There is not enough cancer information to classify it and the other chronic hazards are only based on guesses since there is no hard data. In other words, you want artists to trust this pigment as a safe replacement without telling them that it could one day turn out to be a really bad actor if someone actually tests it for chronic hazards.”

 

 

To be sure, our understanding of biochemistry has come a long way since Napoleon languished on a volcanic island, as has our healthcare system. But there is something to be said for hindsight—it is, as they say, always 20/20. In the 18th century, who knew that color could kill?  Might we look back a decade, a century, or a millennia from now, and rue what we didn’t know about the pigments in use today? Sure, green paint no longer contains arsenic… but maybe there’s another unknown toxin lurking, accumulating in its depths. 

 

Note* All images are sourced from the public domain. 

 

 

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