After a walk, we already notice with the naked eye that shoes can bring dirt into the house: dust, soilsome leaves and, in the worst case scenario, animal feces. And this in itself could be a good reason to take off your shoes before entering the house. But the real problem is what exists at a microscopic level: they are found on the soles of shoes colonies of pathogenic bacteria, as Staphylococcus aureus, Escherichia coli, Clostridium difficileas well as traces of pollutants (such as pesticides and heavy metals) that we unconsciously carry into the home. There is no need to be alarmist, but let’s find out better what is on the soles of our shoes.
What’s under our shoes?
Despite the importance of knowing what we bring into the home, there are few studies and even fewer are independent and published in peer-reviewed journals. But what does this little information we have tell us?
First of all, all shoes are the same: pumps, boots, boots and sneakers, collect bacteria, dust and pollutants in the same way. It just seems like the more knurling the sole has, the more external material it can pick up.
Strains of Enterococcus faecalissign of fecal contamination coming from animal faeces present on pavements.
39.7% of the samples tested positive for Clostridium difficilea bacterium that causes diarrhea, fever, colitis and abdominal pain. Between 40 and 80 percent of the shoes analyzed in a second study bore traces of Listeria monocytogenesresponsible for gastroenteritis due to food poisoning, but which can also cause serious systemic infections, such as meningitis.
In an interesting study conducted in Alaska, participants equipped with sterilized shoes they crossed a short stretch of sidewalk, which ended with a section of linoleum (a type of flooring), simulating the floor of a house. After the walk, the 70% of the boots were found to be contaminated with Coliform bacteria, specifically for 40% of them it was Escherichia coli.
THE’E. coli is a bacterium normally present in the gastrointestinal tract, but some strains are pathogenic and responsible for abdominal cramps, vomiting, diarrhea and if it reaches other districts, urinary infections, pneumonia and systemic infections. To confirm the transfer of these pathogens to the floor, 50% of Coliforms were also found on the linoleum section, 10% of which E. coli.
They were also found on the soles Salmonellacause of food poisoning from ingestion of infected food, infections especially of the gastrointestinal tract, which can worsen and also affect other areas; And strains resistant to antibiotics of Staphylococcus aureusresponsible not only for skin infections, but also for pneumonia and heart infections.
We don’t just carry pathogenic bacteria
The Australian citizen science initiative DustSafe, which involves citizens in collecting samples, found the presence of dust bags sent in by citizens. allergensespecially in the spring season where pollen is at its highest.
There are also heavy metals, pesticides, microplastics and endocrine disruptors, which arrive in our homes mainly from outside. That of lead (even found up to 364 mg/kg) and other heavy metals is traced back to the use of this metal in particular in exterior paintings of the oldest buildings.
How much should we worry about possible risks?
The danger of becoming infected or ill with something on our soles is relatively low. Most of these bacteria cause infections for ingestion of contaminated food or contact with infected feces and on average an adult does not spend much time on the floor. However, it should be considered that a gust of wind or the movement of objects can raise dust from the floors and bring these bacteria back into aerosolwhich could land on food.
Particular attention must be paid if there are people in the house immunosuppressedmore susceptible to pathogen attacks o children who crawl and who, unlike adults, can come into greater contact with these bacteria sedimented on the floors.
This could be a factor to consider hospitals or in structures healthcarewhere hospital infections can complicate already serious clinical cases. According to an analysis, pathogenic bacteria are present on 88% of shoes used outdoors and in particular, at least one pathogenic bacteria was found even in shoes used in the operating room.
As anticipated, other and larger studies are needed to decide whether or not it is a healthy habit, although for now the data points towards this answer. In any case, taking off and having your guests take off their shoes is often a personal choice that is starting to spread in Italy too, or linked to culture of originespecially the Asian one (as all those who grew up with Japanese cartoons will have noticed) and Northern European.
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