Leopards, snakes, lions: these are the creatures most feared by contestants on I'm A Celebrity Get Me Out Of Here! But Paul Chivers, the program's safety chief, is more concerned about a hippopotamus he saw lurking near the set.

Many assume these cute-looking herbivores are friendly; in fact, their bite is stronger than a lion's and they're aggressively territorial. (Often, tourists learn this the hard way.)

No wonder they're Africa's deadliest large land mammal, killing an estimated 500 people each year.

Last year, production was halted when a hippo took a stroll during finale preparations. More recently, one was spotted in a clearing where trials were being filmed.

"We've had everything thrown at us, from hippos to cyclones," says Chivers, known as "Risky" to the 450 crew working from the show's remote South African location. "In a typical day, we might have 30 things to deal with."

To keep the celebrities safe, Chivers spends a lot of time pondering how they might die. Could Fiona O'Loughlin could tumble into a ravine? Might Kerry Armstrong be trampled by a wildebeest? Could Josh Gibson could fall ill from ingesting maggots? 

"The chance of such catastrophic things happening is low, but my job is to explore how these things might happen," Chivers says.

"My job is about balancing great TV with not injuring someone."

In all his years working in television, including a stint on The Amazing Race, Chivers has never knocked back a stunt idea from a producer. Rather, he considers how to make the stunt safe – then puts a price tag on it. 

"If someone wants to jump off a mountain, I'll say, 'No problem.' Then I'll come back and say, 'It'll cost us half a million to do this safely.' That's where [stunt ideas get canned]."

It's much cheaper to arrange the disgusting food challenges. These stunts are relatively safe: the cockroaches celebrities must eat are grown in sterile labs, for instance, while fish eyeballs and pig brains are cleaned and tested for bacteria. 

Not that hosts Julia Morris and Chris Brown make a point of this to contestants; they're too busy trying to gross them out with graphic menu descriptions. (Which is why we saw Gibson gagging over a hairy ostrich anus on the plate in front of him. "It could be worse," fellow contestant O'Loughlin told him. "Think of the poor ostrich.")

"Perception is everything," Chivers says. 

"You want the audience to look at a challenge and go, 'This is crazy.' The excitement comes when the celebrities feel like they're in danger."

I'm A Celebrity Get Me Out Of Here! airs 7.30pm, Sunday to Thursday on Channel Ten.
The journalist travelled to South Africa courtesy of Ten.