Letting your children play with a rubber duck while in the tub may seem like the most harmless of activities and a way to make bath time more fun. But the seemingly harmless toys are actually a breeding ground for mould and bacteria, and could be putting children's health at risk. Mouldy insides Rubber ducks are a novelty many people may allow their children to play with during bath time, but once the toys become wet, they begin to accumulate mould over time. As the mould gathers on the inside of the toy, parents are unknowingly exposing their children to potentially harmful bacteria. To assess the extent of mould damage, we put some household toys to the test and the shocking results in our video will likely turn the stomach of any parents watching. Each of the bath toys were approximately two years old and were used in the bath on most evenings. After use, they would always be squeezed out to get rid of any excess water and would be stored in a dry basket at the side of the tub. The outside of the toys were also regularly cleaned. But when they were cut open, each of the toys were found to be riddled with mould, with the rubber duck in particular found to be the worst affected. As well as some discolouration around the hole at its base, the inside of the toy was completely lined with a slimy black layer of mould and contained some water residue, helping the bacteria to spread. Father of two Steven Chisholm, a JPi Media journalist, decided to conduct the experiment after noticing some of the toys had become discoloured: "I spotted some black residue round the hole in the bottom of the rubber duck and when I held some of the other toys up to the light I could see shadows through the plastic. "Now that I've seen the insides, there's no way I'll be letting my kids play with this kind of toy again. No matter how low the risk is. The smell and sight of the mould turned my stomach." Mould produces a number of allergens, irritants and toxic substances which can affect your health, particularly babies and children (Photo: Shutterstock) What health risks do bath toys pose? Despite the bacteria being hidden on the inside of bath toys, allowing children to play with them could potentially be harmful to their health. Mould produces a number of allergens, irritants and toxic substances which can affect your health, particularly babies and children, according to the NHS. Inhaling or touching mould spores could cause an allergic reaction, such as sneezing, a runny nose, red eyes and skin rashes, or in more severe cases, an asthma attack. Lucy Brown, infection prevention lead at Bupa UK, explained, "As bath toys are kept in a wet environment – and especially as many will be made out of carbon-based plastics - they can provide an ideal breeding ground for bacteria, mould and fungi. "The risk to health is small and certain amounts of bacteria can help to strengthen an immune system. "However, babies and children can be especially sensitive to mould and fungi. "They can harbour potentially pathogenic bacteria which could include Legionella, E. coli, Listeria and Pseudomonas aeruginosa. "As well as this, touching the spores that moulds and fungi produce could result in an allergic reaction or asthma attacks for some children." Inhaling or touching mould spores could cause an allergic reaction, such as sneezing, a runny nose, red eyes and skin rashes (Photo: Shutterstock) How to keep your children safe While the risk to health is small, there are measures parents can take to help keep their youngsters safe if they like to play with bath toys, including regular cleaning with antibacterial soap. Brown advised, "Make sure to shake excess water from bath toys once used, then set them aside to fully dry before storing away. "In addition, regular cleaning of bath toys will help to keep any mould and fungi at bay. "Soak them overnight with antibacterial soap, rinse them well and then allow them to air-dry." This article originally appeared on our sister site, The Sheffield Star