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Yucatán water warning: Mercury and arsenic is turning up in blood and breast milk 

Yucatán’s underground water supply has been contaminated and overexploited, putting residents at cancer risk, a Cinvestav researcher warns.

According to Eduardo Batllori Sampedro, hazardous substances like mercury and arsenic have been found in the general population’s blood, putting residents at heightened risk for cervical and breast cancer.

Yucatán Peninsula hydrological reserves, particularly in the cenote ring, are reaching a critical level of contamination and overexploitation, said Batllori Sampedro. 

Cenote ring Yucatán
The cenote ring is oriented to the Chicxulub crater impact, forever transforming the Yucatán Peninsula. Graphic: Seduna / Yucatán Magazine

The Yucatán’s cenote ring spans 58 municipalities and traces back to the Chicxulub asteroid 66 million years ago. Aside from eventually wiping out the dinosaurs, the impact created a semicircular, highly permeable area now known for an estimated 7,000 cenotes, of which only 3,021 were officially registered by the Office of Sustainable Development as of 2021. 

Within the ring, 99 cenotes are identified as priority areas. This vulnerability has led Batllori to declare a “yellow zone” due to escalating risks of salinization, contamination, and water scarcity. Projections suggest that by 2050, the sea may intrude as far as 20 kilometers inland, further jeopardizing the region’s drinking water supply.

Batllori highlights that the lack of adequate, sustainable water management infrastructure is a significant challenge for the region. He recommends restructuring the region’s water utility, Japay, into a state water commission. But even that approach has its built-in challenges. 

“Municipalities are reluctant to assume water administration responsibilities due to the government turnover every three years,” he said.

Current water treatment facilities fall far short of demand. In Mérida, for instance, although there are 39 treatment plants, they process only five to seven liters of water per second—a minimal amount for the population. Furthermore, 70% of households drain runoff water directly into the ground, which brings contaminants into the water system. Poorly managed landfills have become open-air dumps, worsening subsoil pollution.

Agrochemicals also impact both environmental and human health, Batllori warns.

“Elevated levels of mercury and arsenic have been detected in the blood and breast milk of residents in several communities, exceeding health standards and correlating with cases of cervical and breast cancer,” Batllori says. This contamination stems partly from soil erosion and the loss of vegetation at rates between up to 74,000 acres per year.

The situation in the cenote ring is especially concerning, and Batllori warns of a water recharge deficit. Water extraction is outpacing replenishment, he says, putting the environment and community health at heightened risk.

Cinvestav, the Center for Research and Advanced Studies of the National Polytechnic Institute, is a Mexican non-governmental scientific research institution affiliated with the National Polytechnic Institute. The center has been decentralized and receives federal funding.

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