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Orpiment and arsenic: the yellow poison

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Examining a court fresco, Maomao pauses on the brilliant yellow of a painted garment. She recognizes it as orpiment, a mineral she names as arsenic sulfide, and realizes how a character could have been poisoned without knowing it: through years of painting, the pigment’s arsenic gradually spread through their body, via a brush tip brought to the lips and via dust. The poison hadn’t been administered, it had been breathed and licked, for years.

The subject in depth

Orpiment is a natural mineral, arsenic trisulfide, of a deep golden yellow that made it a sought-after pigment for painters for millennia [Wikipedia] . Its Latin name, auripigmentum, means “gold pigment,” which says enough about the beauty once attributed to it. But its composition is also its curse: it contains arsenic, one of the oldest known poisons.

Yellow orpiment pigment and diagram of chronic arsenic exposure through painting
Orpiment poisons little by little

Arsenic is not a poison like tetrodotoxin or aconitine, which strike quickly at a precise nerve target

[Wikipedia] . It is a cumulative poison, acting deeply on metabolism. It binds to many enzymes, substituting for elements the cell needs, and thereby disrupts energy production. At a high dose, it causes a devastating acute poisoning, with violent digestive distress. At a small, repeated dose, it produces a slow-developing chronic poisoning: fatigue, digestive trouble, skin and nerve damage, and, in the long run, certain cancers.

This chronic form is precisely what the series describes. A painter who uses orpiment daily is exposed through three routes: the dust they breathe, the brush they habitually bring to their mouth to point it, and skin contact. Nothing dramatic day to day, but the arsenic accumulates, and the body eventually becomes saturated with it. The soundness of Maomao’s analysis lies in this reasoning: tracing a symptom back to a discreet, prolonged source of exposure, rather than to a single poisoning event.

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