They find evidence of the oldest mercury poisoning in history in bones from 5,000 years ago in Spain and Portugal

Posted: Nov 18, 2021 14:26 GMT

The poisoning was caused by exposure to cinnabar, a mineral that was pulverized to be used in decorations, paintings and even in funeral rituals, the researchers explain.

A team of scientists has found the oldest evidence of mercury poisoning in 5,000-year-old bones in Spain and Portugal, according to a statement from the University of Seville published on Monday.

The work, which explores the complex interrelationship between humans and mercury over time, is the largest study ever conducted on the presence of this compound in human bones. A total of 14 specialists in biology, chemistry, physical anthropology and archeology participated and used as a sample the skeletal remains of 370 individuals from 50 tombs located in 23 archaeological sites in Spain and Portugal. These bones span 5,000 years of history as they date back to the Neolithic, Copper Age, Bronze Age, and Old Age.

The researchers found that the highest levels of mercury exposure occurred at the beginning of the Copper Age, between 2900 and 2600 BC. C., coinciding with the increase in the exploitation and use of cinnabar – an intense red mineral – for social and cultural reasons.

Cinnabar was historically used to produce pigments for painting, decorations, and funeral rituals. It turns out that the geographic area where the researchers worked is near the largest cinnabar mine in the world, which is located in Almadén, in central Spain. The said mine, declared a World Heritage Site by UNESCO, began to be exploited 7,000 years ago during the Neolithic, which made it possible for cinnabar to become a product with high social and sacred value already in the Copper Age.

The investigation revealed that in tombs discovered in southern Portugal and the Spanish autonomous community of Andalusia, this powder was used to paint megalithic chambers, decorate statuettes or stelae, and spread it over the dead. As a result, many people must have accidentally inhaled or consumed it, causing large accumulations of mercury in their bodies.

The study recorded levels of up to 400 parts per million (ppm) in the bones of some of these individuals. Taking into account that, according to the World Health Organization (WHO), exposure to mercury even in small amounts can cause serious health problems, the analyzed bodies had a high level of intoxication.

In fact, the levels that were detected in some subjects are so high that the study authors do not rule out that powdered cinnabar was deliberately consumed, by inhalation of vapors, or even ingestion, due to the symbolic and esoteric ritual value attributed to it. in the past.

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