Reptile Shells Uncover Nuclear Contamination History: Tortoises and Turtles as Environmental Timekeepers


Tortoises and turtles have emerged as unlikely environmental timekeepers, revealing insights into historical nuclear contamination. Research published in PNAS Nexus demonstrates that the layers of shells from these reptiles can serve as a chronological marker for periods marked by nuclear fallout. Comparable to tree rings and ice cores offering climate and temperature data, the layers of these shells contain records of their surroundings.

By analyzing chelonians, the reptilian order including tortoises and turtles, researchers investigated uranium accumulation in their scutes – the outer bony shells made of keratin. Each shell layer corresponds to a year of the creature’s life, providing a historical record. Sea turtles from Enewetak Atoll, which experienced 67 nuclear tests, displayed uranium contamination even two decades after testing ended. Likewise, an eastern box turtle from Oak Ridge, Tennessee, site of a nuclear facility since 1943, exhibited signs of uranium accumulation potentially linked to the area’s uranium waste products.

The study highlights that these reptiles can accumulate human-made radionuclides both through direct exposure and environmental factors. Their lengthy lifespans make them effective natural record-keepers, documenting human activities and nuclear landscapes over extended periods.


This novel approach underscores the intersection of wildlife and science, demonstrating how seemingly unrelated creatures can provide crucial historical insights into environmental impacts. The research suggests that merging analyses of historical and current specimens could significantly enhance ongoing nuclear contamination investigations, expanding our understanding of the consequences of nuclear activities on ecosystems.