Conservation scientists in South Africa are injecting rhino horns with radioactive isotopes. The doses are too weak to harm the animals, but strong enough to set off nuclear security system alarms at international border crossings.

A South African university has launched an anti-poaching campaign to inject the horns of rhinos with radioactive isotopes, which it says are harmless to the animals but can be tracked by authorities.

Scientists have developed a safe way to embed radioactive markers in rhino horns, making them detectable and help combat illegal poaching.