Scientists have clarified the mystery behind the striking blue colouring seen on dogs roaming within the Chernobyl exclusion zone—firmly ruling out radiation as the cause. The speculation began after images of the unusually coloured animals were shared on The Dogs of Chernobyl Facebook page, which regularly highlights the struggles faced by stray dogs inhabiting the contaminated area. The photographs quickly fuelled online conspiracy theories, with some social media users claiming the colour change was triggered by lingering radiation or represented a new evolutionary response to the environment.
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Experts, however, have now dismissed those claims. According to researchers, the dogs likely picked up the vivid blue dye from a toppled portable toilet, rolling in the waste inside—a behaviour many dog owners would recognise.
“The blue dye likely came from a tipped-over porta loo where the dogs were rolling about in the mess, as dogs are inclined to do,” explained Timothy Mousseau, a scientist at the University of South Carolina, in a Facebook post.
He stressed that the colouring has nothing to do with radiation. “Despite the social media hype, the blue dogs of Chornobyl do not reflect any form of mutation or evolutionary adaptation. It’s simply the result of the dogs’ unsanitary behaviour around a fallen portapotty.”
Chernobyl remains synonymous with the catastrophic 1986 nuclear disaster, when one of the plant’s reactors exploded, releasing radioactive material across vast regions and resulting in the deaths of 31 people. The long-term health consequences have affected tens of thousands of Ukrainians.
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Following the explosion, the Soviet authorities established a 30km exclusion zone around the plant and evacuated more than 120,000 residents from surrounding towns, initially telling them the relocation would last only three days. Pets were left behind and ultimately became strays.
Early efforts to eradicate stray dogs were halted after workers objected to the practice on humanitarian grounds. The Clean Futures Fund (CFF) eventually stepped in, leading monitoring and care efforts for the animals. By 2017, the CFF had launched the Dogs of Chernobyl programme, aimed at neutering, vaccinating and supporting the canine population that continues to inhabit the zone. Today, veterinarians, technicians, scientists, dog catchers and volunteers work together to care for an estimated 250 dogs living near the former power plant, ensuring they receive ongoing support despite the challenging environment.
