As disgusting as it might sound, according to experts you could be eating your poo without realising it and it all has to do with where you place your toothbrush.

Hygiene expert Paul Mangold warns that keeping your toothbrush close to your toilet could cause bouts of severe gastrointestinal illness.

“Every time you flush your toilet, poo particles are flung into the air,” he says. “These bio-aerosols can be extremely harmful and the airborne water droplets are often contaminated with viruses and bacteria.

“Previous scientific studies have shown how E. coli, Clostridium difficile and norovirus can all be transmitted in this way – and if you keep your toothbrush near your toilet, these potentially deadly bugs can land on the bristles before you put them straight into your mouth, twice a day.

“Toothbrushes themselves are the perfect breeding ground for germs. Bacteria love moist areas where they can grow and multiply, and toothbrushes are usually damp. And what’s more, research has shown that harmful particles can linger in the air for at least 30 minutes after each flush – and that they can disperse as far away as three metres from the toilet itself.”

A US team from the University of Iowa led by Dr Matthew Nonnenmann recently used a sophisticated particle-collecting machine, placed one metre away from a toilet, to measure the airborne matter both pre and post flush.

They found that flushing ‘significantly increased’ the number of harmful particles sent airborne.

More worrying still, these bio-aerosols were still present in the air even when an empty toilet was being flushed – as ‘residual’ matter from previous toilet users was flung up into the room.

And there was also no difference in particle concentrations over the course of the 30 minute sampling time – which suggests the matter could linger for far longer.

Dr Matthew Nonnenmann, who led the study, says: “Flushing significantly increased the number of particles and bioaerosol concentrations. Our study detected bioaerosols produced from toilets that were flushed containing no waste, suggesting bacteria remain in the toilet from previous toilet use.

“When flushed, the agitation of the water could loosen bacteria attached to the wall and be released into the air.”

Paul says many bathrooms in Australia will feature toothbrushes lined-up on a shelf above, or in close proximity to, the lavatory.

“I think a lot of people are simply unaware of the dangers,” he says. “Because bacteria from the toilet spread to other areas of the room, it’s really important to clean all bathroom surfaces regularly to stop the spread of pathogens.

“And make sure you replace your toothbrush every three months, too, in order to minimise the risks.”

One of the most detailed pieces of research into flushes and infectious poo particles came in 2013, by the University of Oklahoma Health Science Center.

Scientists found that the more powerful the flush on your toilet, the more pathogen particles were thrown into the air.

Lead author David Johnson says: “The number of droplets appeared to increase with increasing flush energy, with statistically significant differences in droplet production across toilets.

“These results provide additional support for concerns that flush toilets could play a role in airborne transmission of infectious disease via droplet nuclei bioaerosols.”