Poison to stop slaughter

Safe for animals but potentially fatal for humans, it can stop illicit trade.

The fight against rhino poaching just stepped up a gear: scientists have started injecting radioactive material into live rhino horns to make them easier to detect at border posts - but the material is hazardous to human health... something which may collapse the demand for horns.

South Africa is home to a large majority of the world's rhinos and is a hotspot for poaching-driven by demand from Asia, where horns are used in traditional medicine for their supposed therapeutic effect.

At the Limpopo rhino orphanage in the Waterberg area, a few of the thick-skinned herbivores grazed in the low savannah.

James Larkin, director of the University of the Witwatersrand's radiation and health physics unit who spearheaded the initiative, said he had put "two tiny little radioactive chips in the horn" as he administered the radioisotopes on one of the animals' horns.