The National Autonomous University of Mexico (UNAM) has issued an aquifer contamination warning for the Guanajuato municipality of San José Iturbide given high levels of radioactivity detected in at least 2,500 wells.
UNAM researcher Marcos Adrían Ortega told the newspaper Milenio that at least half of those wells supply water for farming, and that five people have died of related health complications.
Tens of stomach cancer cases are also being studied for links with the contamination, said the researcher based at the Juriquilla UNAM campus, located in Querétaro.
One well that supplies water to three San José communities showed elevated levels of alpha radiation, which could be related to the fatal cases of lymphoblastic leukemia in girls younger than 12 years old reported in the area.
Around 1,500 people from San José show some degree of radioactive contamination, said the specialist, but relocating them is not the solution, as the source of the pollution is an over-exploited aquifer that extends over a broader region.
Studies have determined that the concentrations of arsenic and fluoride in the Lerma-Chapala aquifer have doubled in the last 14 years, and that similar levels of contamination could be present in the underground reservoirs of six states: Querétaro, San Luis Potosí, Aguascalientes, Zacatecas, Durango and Sinaloa.
Ortega said the damage caused by over-exploitation of the interconnected aquifers extends 800 kilometers from San José Iturbide, and that in some areas arsenic levels are 20 to 30 times over the acceptable limits.
“Arsenic is a cause of cancer, and fluoride not only affects teeth but also the skeleton,” said the researcher.
“The age of water in these underground reservoirs is between 10,000 and 35,000 years, and the ‘younger’ waters have already been extracted,” explained Ortega.
He explained that naturally occurring pollutants such as arsenic, fluoride and sodium in deep, underground waters are now flowing to the surface, affecting human health.
Ortega said that high concentrations of naturally occurring radon, a radioactive, colorless, odorless, tasteless gas has also been detected, not only in groundwater used for human consumption, but also in the soil and air, in a radius of three kilometers surrounding San José.