As per the study, squeeze-top bottles are the cleanest of the three styles tested. (Unsplash/Rep pic)
A new study has found that reusable bottles can harbour around 40,000 times more bacteria than the average toilet seat.
A team of researchers from US-based waterfilterguru.com swabbed different parts of water bottles including the spout lid, screw-top lid, stray lid and squeeze-top lid, three times each, and found two types of bacteria present - gram-negative rods and bacillus, HuffPost reported.
"They are objects that can't betray us," Australian Catholic University clinical psychologist and hoarding disorder expert, Associate Professor Keong Yap, said, comparing the phenomenon with objects children use to soothe anxiety (like stuffed toys). "They are reliable and predictable, unlike people who can hurt us," Mr Yap added.
In their study, the researchers explained that while gram-negative bacteria can cause infections that are increasingly resistant to antibiotics, certain types of bacillus can result in gastrointestinal issues. They compared the cleanliness of the bottles to household objects and stated that they contain twice as many germs as the kitchen sink, can harbour four times the amount of bacteria as a computer mouse and 14 times more than a pet's drinking bowl.
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"The human mouth is home to a large number and range of different bacteria," Imperial College London molecular microbiologist, Dr Andrew Edwards, said, as per New York Post. "So it's not surprising that drinking vessels are covered in microbes," he added.
However, even though bottles may serve as a breeding ground for high numbers of bacteria, a microbiologist at the University of Reading, Dr Simon Clarke, said that it is not necessarily dangerous. "I've never heard of someone getting sick from a water bottle. Similarly, taps are clearly not a problem: when did you last hear of someone getting ill from pouring a glass of water from a tap? Water bottles are likely to be contaminated with the bacteria that are already in people's mouths," Mr Clarke said.
Further, the study revealed that squeeze-top bottles are the cleanest of the three styles tested, with a tenth of the amount of bacteria as one with a screw-top or straw-fitted lid. The researchers recommended washing reusable bottle at least once a day with hot soapy water, and sanitizing it at least once a week.