Unless you would like a date with the porcelain, put your lunch in the fridge.
That's the advice from the Food Safety Information Council, which warns that many Australians fail to follow simple instructions to avoid food poisoning.
But employers appear to need to help out - a recent council survey found that many of the office workers who don't use the fridge for their lunch believe that it's more an incubator for food disasters than a way to keep food clean and cool.
The annual survey of about 1200 people found that three-quarters of office workers take their lunch to work, but 10 per cent of that number fail to put their lunch in the fridge.
The results were worse for school lunches: more than one-quarter of parents fail to put a frozen drink or ice block with their child's lunch - up 8 per cent on the survey in 2011.
"Food poisoning can have horrific long-term consequences, including reactive arthritis," Michael Eyles, council chair, said.
The council warns that food poisoning costs Australia an estimated $1.25 billion each year, including 2.1 million days lost at work and 1.2 million visits to the doctor.
The figures are calculated by microbiologists at the federal government entity OzFoodNet.
Dr Eyles warned that lunchboxes needed to be washed and dried daily and should be replaced if cracked, split or shattered
"Bugs will grow in any cracks," he said. "Avoid risky foods such as soft cheeses, sprouts and pate."
As for the workplace, employers should keep the fridges in good working order and make sure that they do not become overcrowded.
"Rather than avoid it, become friends with that fridge at work that no one seems to own," Dr Eyles said. "Make sure it is clean and not packed with ageing food."
And it's always good etiquette to ensure that if you open the fridge, you also close it properly.