Steve Smit of Monkey Helpline said the stomach contents from the monkeys tested positive for a highly toxic substance.
“The first test didn’t detect anything, but the private laboratory used a different test which confirmed that it was endosulfan organochlorine insecticide, which has been banned since 2012,” Smit said.
He said the insecticide was similar to DDT (dichlorodiphenyltrichloroethane), and in South Africa it had led to the deaths of at least 13 children.
Smit said that after the poisoning, 22 monkeys were removed from eMdloti; after treatment, seven were returned to the troop and 13 died.
“Three monkeys died a few weeks after the poisoning, bringing the total to 16 monkeys that died,” he said.
Two monkeys were still in their care. An adult male that had neurological issues would be released today while the young female would remain at the Monkey Helpline sanctuary because it would take longer for her to recover.
“The monkeys that were released last month are doing better,” said Smit.
Police said the poisoning of the monkeys was still under investigation.
CropLife SA operations and stewardship manager Dr Gerhard Verdoorn confirmed that the insecticide was banned in South Africa.
“This is the second case of poisoning I have heard about in 12 years. The first was the poisoning of blue cranes,” Verdoorn said.
In 2012, then minister of Agriculture, Forestry and Fisheries Tina Joemat-Pettersson prohibited the acquisition, disposal, sale or use of an agricultural remedy containing endosulfan.
Coast to Coast Special Investigations private investigator Sean Pierce said the lab reports had been handed over to the police.