Radioactive Contamination in Feral Dogs in the Chernobyl Exclusion Zone: Population Body-Burden Survey and Implications for Human Radiation Exposure

Abstract

This report describes a two-year effort to survey the internal 137Cs and external β-emitter contamination present in the feral dog population near the Chernobyl nuclear power plant (ChNPP) site, and to quantify the potential for human radiation exposure from this contamination. This work was performed as an integral part of the radiation safety and control procedures of an animal welfare oriented trap-neuter-release (TNR) program. The measurement program employed handheld β-sensitive probes, and a simple whole-body counter to measure internal 137Cs burden during post-surgical observation and recovery. External β contamination surveys performed during intake showed that 21/288 animals had significant, removable external contamination. Measurements with the whole-body counter indicated internal 137Cs body burdens ranging from undetectable (minimum detection level ∼100 Bq/kg in 2017, ∼ 30 Bq/kg in 2018) to approximately 30,000 Bq/kg. A total of 33 animals had 137Cs body-burdens above 1 kBq/kg. We observe that internal contamination levels are positively correlated with capture locations within ChNPP boundaries. The large variation in the 137Cs concentration in these animals is not well-understood, could be due to prey selection, access to human food scraps, or extended residence in highly contaminated areas. These internally-contaminated animals are unlikely to pose an exposure hazard despite their large body-burdens due to their limited exposure to humans. However, the small minority of animals with external contamination may pose a contamination hazard to workers, tourists, and others interacting with the dogs, as evidenced by total quantity of removable activity and incidents of transfer to materials used in animal capture.