Study reveals ancient Mayan cities were ‘dangerously contaminated’ with mercury

By Stephen Beech via SWNS

The cities of ancient Maya were "dangerously contaminated" with mercury, reveals a new study.

Exposure to mercury may have posed a health hazard for the residents, say scientists.

The Maya civilization was noted for having the most sophisticated and highly developed writing system in the pre-Columbian Americas—as well as for its art, architecture, mathematics, calendar, and astronomical system.

Descendants of the Maya still live in Central America in modern-day Belize, Guatemala, Honduras, El Salvador and parts of Mexico.

The cities of the ancient Maya in Mesoamerica never fail to impress, scholars say.

But beneath the soil surface, an unexpected danger lurks there: mercury pollution.

In a study, published in the journal Frontiers in Environmental Science, researchers conclude that pollution isn’t modern.

They believe it’s due to the frequent use of mercury and mercury-containing products by the Maya of the Classic Period, between 250 and 1100 AD.

The research team says that the pollution is in places so heavy that even today, it poses a potential health hazard for unwary archeologists.

Study lead author Professor Duncan Cook, of the Australian Catholic University, said: “Mercury pollution in the environment is usually found in contemporary urban areas and industrial landscapes.

"Discovering mercury buried deep in soils and sediments in ancient Maya cities is difficult to explain until we begin to consider the archeology of the region which tells us that the Maya were using mercury for centuries.”

For the first time, Cook and colleagues here reviewed all data on mercury concentrations in soil and sediments at archeological sites across the ancient Maya world.

They show that at sites from the Classical Period for which measurements are available – Chunchumil in today’s Mexico, Marco Gonzales, Chan b’i, and Actuncan in Belize, La Corona, Tikal, Petén Itzá, Piedras Negras, and Cancuén in Guatemala, Palmarejo in Honduras, and Cerén, a Mesoamerican ‘Pompeii’, in El Salvador –mercury pollution is detectable everywhere except at Chan b’i.

Concentrations range from 0.016 ppm at Actuncan to an "extraordinary" 17.16 ppm at Tikal. For comparison, the Toxic Effect Threshold (TET) for mercury in sediments is defined as 1 ppm.

The researchers say that sealed vessels filled with ‘elemental’ liquid mercury have been found at several Maya sites, for example, Quiriqua in Guatemala, El Paraíso in Honduras, and the former multi-ethnic megacity Teotihuacan in Central Mexico.

Elsewhere in the Maya region, archeologists have found objects painted with mercury-containing paints, mainly made from the mineral cinnabar.

The research team concluded that the ancient Maya frequently used cinnabar and mercury-containing paints and powders for decoration.

They say that mercury could then have leached from patios, floor areas, walls, and ceramics, and subsequently spread into the soil and water.

Co-author Professor Nicholas Dunning, of the University of Cincinnati in the US, said: "For the Maya, objects could contain ch’ulel, or soul-force, which resided in blood.

"Hence, the brilliant red pigment of cinnabar was an invaluable and sacred substance, but unbeknownst to them it was also deadly and its legacy persists in soils and sediments around ancient Maya sites."

As mercury is rare in the limestone that underlies much of the Maya region, the researchers speculated that elemental mercury and cinnabar found at Maya sites could have been originally mined from known deposits on the northern and southern confines of the ancient Maya world, and imported to the cities by traders.

They say that so much mercury would have posed a health hazard for the ancient Maya: for example, the effects of chronic mercury poisoning include damage to the central nervous system, kidneys, and liver, and cause tremors, impaired vision and hearing, paralysis, and mental health problems.

The researchers pointed out that It’s perhaps significant that one of the last Maya rulers of Tikal, Dark Sun, who ruled around 810 AD, is depicted in frescoes as pathologically obese.

Obesity is a known effect of metabolic syndrome, which can be caused by chronic mercury poisoning.

The team say more research is needed to determine whether mercury exposure played a role in larger sociocultural change and trends in the Maya world, such as those towards the end of the Classic Period.

Co-author Professor Tim Beach, of the University of Texas at Austin, added: “We conclude that even the ancient Maya, who barely used metals, caused mercury concentrations to be greatly elevated in their environment.

"This result is yet more evidence that just like we live today in the ‘Anthropocene’, there also was a ‘Maya anthropocene’ or ‘Mayacene’.

"Metal contamination seems to have been an effect of human activity through history.”