A town built on lead
Tekeli is a single-industry town, or "monotown," in the foothills of the Dzhungar Alatau mountains. Its existence was tied to the massive Tekeli lead-zinc processing plant, a major industrial complex in the Soviet Union. For decades, the smelter processed polymetallic ores, releasing heavy metals into the local environment. The industrial waste, including lead, zinc, and cadmium, was collected in large dumps and tailings ponds, leaving contaminated for the soil and water. Even after the smelter ceased operations, the legacy of its emissions remained in the form of fine, toxic dust spread across the region. Studies of the soil near the tailings have shown lead accumulation more than double the maximum allowable concentration (MAC).
This persistent contamination poses an ongoing environmental problem. Rain and snowmelt can wash harmful compounds from the waste dumps into the Karatal River basin, affecting a wider area. The concentration of these heavy metals in the soil creates a direct pathway for human exposure. Children are especially vulnerable because they play outdoors and are more likely to ingest contaminated soil and dust through normal hand-to-mouth activity.
Isotopic evidence in teeth
Scientists discovered a definitive link between the smelter's pollution and lead exposure in local children using isotopic analysis. Lead has four stable isotopes, and the ratio between them varies depending on the geological origin of the lead ore. This creates a unique signature for a specific source of contamination. Researchers analyzed this lead isotope signature from the smelter's waste and compared it to the lead found in donated deciduous (baby) teeth from children who grew up in Tekeli.
Tooth enamel and dentine form during childhood and lock in the chemical signatures of the environment at that time. The analysis showed a direct match between the isotopic fingerprint of the smelter's lead and the lead embedded in the children's teeth. This provided clear evidence that the lead from the industrial site was being absorbed into their bodies.
The most alarming finding was that this exposure continued long after the plant's closure in 1990. Children born years later still showed the smelter's lead signature in their teeth, demonstrating that the contaminated dust in the soil is a source of exposure. There is no known safe level of lead exposure. It is particularly harmful to the developing brains of children, where it can cause permanent neurological damage, learning difficulties, and lowered IQ.