Owners of watches and fitness trackers might want to look away now: a new study has revealed that 95 percent of 20 different smartwatch wristbands tested were contaminated with bacteria capable of causing disease.

The research team, from Florida Atlantic University, tested for the potentially pathogenic species of Staphylococcus, Enterobacteria (like Escherichia coli), and Pseudomonas, which can all cause infections under certain conditions.

There were variations in the type of wristband used, however: rubber and plastic bands had the most bacteria on them, while the metal bands tested (especially gold and silver) were virtually free from bacteria.

"Plastic and rubber wristbands may provide a more appropriate environment for bacterial growth as porous and static surfaces tend to attract and be colonized by bacteria," says biological scientist Nwadiuto Esiobu from Florida Atlantic University.

While research has shown wristwatches and the like can be potential sources of infection in hospital settings, few investigations have dug into the details of how different materials harbor opportunistic microbes in the general community.

The bacteria tested for in this study are among the more common ones found on the body and in the environment. In the right (or rather wrong) conditions, they can lead to diseases such as abscesses, pneumonia, and salmonella.

There were no noticeable differences between male and female participants in the study, though the activities engaged in did have an effect – wristbands from gym goers had the highest levels of staphylococcal bacteria.

The study points out something of an anomaly in our usual sanitation routines: while watches and other wearables are worn for most or all of the day, we rarely think about cleaning them (though credit to you if you do).

"The quantity and taxonomy of bacteria we found on the wristbands show that there is a need for regular sanitation of these surfaces," says Esiobu. "Even at relatively low numbers these pathogens are of public health significance."

"Importantly, the ability of many of these bacteria to significantly affect the health of immunocompromised hosts indicates a special need for health care workers and others in hospital environments to regularly sanitize these surfaces."

The researchers also tested a few different cleaning substances to see which was most effective: a Lysol-branded disinfectant spray, a 70 percent ethanol mix (of the sort often used in hospitals), and apple cider vinegar, a more natural mixture.

In terms of bacteria bashing, the Lysol spray and ethanol mix killed off 99.9 percent of bacteria within 30 seconds across all materials, though the apple cider vinegar wasn't quite as potent against all bacteria types, and needed longer to work.

The researchers are keen that their work raises awareness of the need to give our wearables an occasional scrub down – and that applies to all the other gadgets that regularly come into contact with our skin every day.

"Other potential forms of bacterial transmission and facilitation of infection, such as earbuds or cell phones, should be similarly studied," says Esiobu.

The research has been published in Advances in Infectious Diseases.