For kids with a sensory processing disorder, a tumble in a pit full of plastic coloured balls can be more than a bit of fun. It can often be an important tool for diagnosis and treatment.
Research suggests it might also leave some with more than improved body awareness. A swab of the balls in therapy pits last year found a bunch of microbes commonly responsible for some rather nasty infections.
You might be as surprised as we were to learn there isn't a US national standard for cleaning ball pit enclosures.
We're not just talking about that dank corner in the playground of the local fast food joint either. Even the kinds of pits young children on the autism spectrum might paddle through for therapy also don't legally require frequent disinfecting.
Researchers from the University of North Georgia in the US wanted to know if this oversight poses a problem.
"Accordingly, clinics may go days or even weeks between cleanings, which may allow time for microorganisms to accumulate and grow to levels capable of transmission and infection," they write in their report.
Tiny humans aren't always the cleanest members of society. (No offence to any toddlers reading this.)
Previous research conducted more than 20 years ago in the US state of Virginia revealed ball pits to be full of the kinds of garden variety microflora we find on our bodies and in our outside environment.
A quick and dirty survey conducted several years ago in the UK claimed just one in a thousand pits might be free of the kinds of bodily fluids our precious little microbe factories churn out on a daily basis.
Whether or not you think it's a credible statistic, one might hope that therapy ball pits commonly used to help kids with serious sensory conditions would have a high standard of clinical level hygiene.
To test this, the researchers visited half a dozen ball pits attached to inpatient physical therapy clinics or outpatient clinics across the state of Georgia and randomly borrowed nine to 15 balls taken from various depths.
After a quick swab and a 24 hour wait for the cultured plates to bloom, they went about identifying the kinds of microorganisms clinging to each plastic sphere, and coming up with a rough estimate on their prevalence.
All up they were able to identify 31 bacterial species, as well as a single species of potentially pathogenic yeast. In some cases the number of cells per ball counted into the thousands.
While we know that the presence of microbes doesn't always mean danger, in this case the team did find a few bad boys capable of causing life-threatening problems, should they happen to find an opportunity to cause an infection.
Enterococcus faecalis, for example, is often responsible for urinary tract infections, especially in a hospital setting. Then there's Acinetobacter lwofii, a hardy microbe that's gaining a nefarious reputation as a pathogen in neonatal intensive care units.
These results aren't necessarily a cause for significant levels of concern. The world belongs to the microbe, after all, and unless a child is immunocompromised, they will usually cope just fine swimming through a bug sea.
But the fact some facilities were less pristine than others should ring alarm bells.
"We found considerable variation in the number of microorganisms between the different ball pit samples," says physical therapist Mary Ellen Oesterle.
"This suggests that clinics utilise different protocols for cleaning and maintenance, potentially representing a broader need to clarify and establish standards that reduce the risk of transmission."
In light of the rising threat of superbugs transforming relatively common microflora into nightmares of infection, top quality sanitation should be considered more than a courtesy. It should be mandatory, especially for utilities attached to health facilities.
When it comes to your average backwater ball pit, it's fair to say jump at your own risk.
But for kids who are invited to play for their health, picking up a bad case of gastro – or worse – just shouldn't be part of the plan.
This research was published in the American Journal of Infection Control.