Study decodes ‘unexpected danger’ lurking beneath ancient Mayan cities

According to new research, ancient Mayan cities were contaminated with “dangerous” levels of mercury that could have posed a health risk to people living in the Mesoamerican civilization.

The review of studies, recently published in the journal Frontiers in environmental sciences, discovered the “unexpected danger” of mercury pollution beneath the ground surface of ancient Maya cities in Mesoamerica, likely due to the frequent use of mercury and mercury-containing products by the inhabitants of this region. period between 250 and 1100 CE.

“Discovering mercury buried deep in soils and sediments in ancient Mayan cities is difficult to explain, until we start to consider the archeology of the region which tells us that the Maya used mercury for centuries” , study co-author Duncan Cook of the Australian Said Catholic University.

In the study, scientists examined for the first time all data on mercury concentrations in soil and sediment from archaeological sites in the ancient Maya world.

They found mercury concentrations ranging from 0.016 parts per million (ppm) in some areas to “extraordinary” levels of 17.16 ppm in other places.

By comparison, the researchers say the toxic effect threshold (TET) for mercury in sediment is defined as 1 ppm.

Citing previous studies, they say sealed vessels filled with liquid mercury have been reported at several ancient Maya sites, including Quiriqua in Guatemala, El Paraíso in Honduras and the multi-ethnic megacity of Teotihucan in central Mexico.

Archaeologists have also previously unearthed paintings containing mercury, mostly made from the mineral cinnabar, at other locations in the Maya region.

Based on these observations, scientists claim that the ancient Maya may have frequently used paints and powders containing cinnabar and mercury for decoration.

This mercury, they say, may have leaked from patios, floors, walls, and ceramics, and into soil and water.

“For the Maya, objects could contain ch’ulelor fortitude, which resided in the blood,” said Nicholas Dunning, another study co-author from the University of Cincinnati in the United States.

“Therefore, the brilliant red pigment of cinnabar was a priceless and sacred substance, but unbeknownst to them it was also deadly and its legacy lives on in the soils and sediments around ancient Maya sites,” Dr Dunning explained.

Researchers suspect that elemental mercury and cinnabar found at Maya sites may have originally been mined from known deposits on the northern and southern reaches of the ancient Maya world, and brought into cities by traders.

The widespread use of the metal may have posed a health risk to the ancient Maya, scientists say.

Studies have shown the toxic effects of chronic mercury poisoning, including damage to the central nervous system, kidneys, and liver.

The liquid metal is also known to cause tremors, impaired vision and hearing, paralysis and mental health issues.

Scientists are calling for new research to determine if mercury exposure played a role in broader socio-cultural changes and trends in the ancient Maya world.

“We conclude that even the ancient Mayans, who barely used metals, caused a large elevation in mercury concentrations in their environment,” said Tim Beach, another study author from the University of Texas at Austin.

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