You're safer to eat your lunch off a toilet seat than the average office desk - and be careful how you handle the taps on the way out: they're filthy.

Germ-busting microbiologist Dr Charles Gerba, of Arizona University in the United States, advises not to eat in either place and to regularly sanitise hands and disinfect surfaces.

He has been brought to New Zealand by a cleaning company to advise employers on simple steps to reduce staff sick days. He says regularly sanitising surfaces with disinfecting wipes has been shown to reduce absenteeism of office workers by up to 30 per cent and of schoolchildren by more than 50 per cent.

His research has found that dishcloths at home typically harbour more E. coli - bacteria that indicate faecal contamination - than the toilet.

"There's more faecal bacteria in your kitchen sink than in your toilet after you flush it. People nuke their bathrooms, but not their kitchens," Dr Gerba said yesterday.

"There are 200 times more E. coli on the cutting board than on a toilet seat. It's safer to make a sandwich on a toilet seat than on a cutting board in the average home."

This is because many home cooks fail to properly sanitise the board after cutting up raw meat, or do not have separate boards for raw meat and ready-to-eat foods.

But things only get worse at work.

The phone and the desktop are the "germiest" items in the office. The number of bacteria per square centimetre on a desk top is typically 400 times greater than on a toilet seat.

"The computer keyboard and mouse are next worst, then the drawers."

On your way into the office toilet, consider that the door handle on the way in will be loaded with bad bugs, as will the underside of the toilet seat and especially the taps. But the door handle on the way out won't be so bad, because most people have washed their hands.

Dr Gerba said schools and daycare centres were the most unhygienic workplaces in his research, because children were less likely than adults to wash their hands and they picked up lots of germs from playgrounds.

Germs were easily transferred from our hands into our noses, mouths and eyes because we touched our faces so much - 80 times an hour for children and 16 times for adults.

He urged frequent use of hand sanitiser and regularly cleaning desks, phones, keyboards and computer mice with disinfectant wipes.

Least Hygienic Workplaces

Among white-collar workers, the highest concentrations of harmful bacteria and viruses were found on surfaces used by:

1. Schoolteachers

2. Bankers

3. Accountants

4. Media workers

5. Doctors

- Source: Arizona University research