Clearly, ancient Egyptians didn't get the memo about lead poisoning. Their eye makeup was full of the stuff. Although today we know that lead can cause brain damage and miscarriages, the Egyptians believed that lead-based cosmetics protected against eye diseases. Now, new research suggests that they may have been on to something.
Previous work indicates that the Egyptians added lead to their cosmetics on purpose. When analytical chemist Philippe Walter and colleagues at CNRS and the Louvre Museum in Paris analyzed the composition of several samples of the Egyptians' famous bold, black eyeliner in the Louvre's collection, they identified two types of lead salt not found in nature. That means that ancient Egyptians must have synthesized them. But making lead salt is a tricky, delicate process that requires tending for weeks--and unlike other common makeup components, the salts are not glossy. So why did they bother?
Ancient manuscripts gave the scientists a clue. It turns out that in those days, people made lead salts and used them as treatments for eye ailments, scars, and discolorations. When Walter told analytical chemist Christian Amatore of the Ecole Normale Supérieure in Paris about the findings, Amatore says he was intrigued because lead is now known to have so many toxic effects.
To see if the lead might confer any health benefits, Amatore, Walter, and colleagues added lead salts to human skin cells called keratinocytes, which were grown in the lab.
Ancient Egypt's stunning eye make-up not only shielded wearers from the dark deeds of the evil eye but also protected them against eye disease, French scientists said Thursday.
Ancient Egyptians some 4,000 years ago produced the make-up used to darken and adorn eyes with lead and lead salts in mixtures that sometimes took a month to concoct, said Philippe Walter, who co-headed a team of scientists from the Louvre museum and the CNRS national research institute.
"We knew ancient Greeks and Romans too had noted the make-up had medicinal properties, but wanted to determine exactly how," he told AFP.
Contrary to widely held belief that lead is harmful, the team, using analytical chemistry, determined that 'in very low doses lead does not kill cells'. Instead, it produces a molecule - nitric oxide - that activates the immune defence system which beats back bacteria in case of eye infection.
The research was carried out using a tiny electrode, the 10th of the size of a hair, to look at the effect of a lead chloride synthesised by the Egyptians - laurionite - on a single cell.
The study was released on Thursday online by the journal Analytical Chemistry.
The Abstract for the article in Analytical Chemistry, on the above page, is as follows:
Issa Tapsoba, Stphane Arbault, Philippe Walter and Christian Amatore . . . .
Lead-based compounds were used during antiquity as both pigments and medicines in the formulation of makeup materials. Chemical analysis of cosmetics samples found in Egyptians tombs and the reconstitution of ancient recipes as reported by Greco-Roman authors have shown that two non-natural lead chlorides (laurionite Pb(OH)Cl and phosgenite Pb2Cl2CO3) were purposely synthesized and were used as fine powders in makeup and eye lotions. According to ancient Egyptian manuscripts, these were essential remedies for treating eye illness and skin ailments. This conclusion seems amazing because today we focus only on the well-recognized toxicity of lead salts. Here, using ultramicroelectrodes, we obtain new insights into the biochemical interactions between lead(II) ions and cells, which support the ancient medical use of sparingly soluble lead compounds. Submicromolar concentrations of Pb2+ ions are shown to be sufficient for eliciting specific oxidative stress responses of keratinocytes. These consist essentially of an overproduction of nitrogen monoxide (NO°). Owing to the biological role of NO° in stimulating nonspecific immunological defenses, one may argue that these lead compounds were deliberately manufactured and used in ancient Egyptian formulations to prevent and treat eye illnesses by promoting the action of immune cells.