4 reasons wearing shoes inside is bad for your health, from 'forever chemicals' to hidden poop germs

• Environmental health researchers say leaving your shoes at the door may protect your health.
• Shoes can carry a variety of pathogens, including E. coli borne on hidden particles of poop.

Wearing your shoes indoors may accidentally welcome some health hazards into your home, according to a pair of environmental scientists writing for The Conversation.

Germs, as well as "forever chemicals" that can linger in your body or home for years, can sneak inside via the soles of your shoes, so leaving them at the door may protect your health, they wrote.

To help minimize your exposure to pesticides, lead-contaminated soil, and disease-causing bacteria like E. coli, take off your shoes when you get home, experts say.

Disease-causing poop pathogens can lurk on your sneakers

The soles of your shoes can serve as a vehicle for a variety of infectious diseases, according to data.

Pathogens on your shoes range from Salmonella and Listeria, which are both linked to food poisoning, to Staphylococcus, the bacteria behind Staph infections, and many more, according to a 2016 study.

The study found that up to 80% of shoes could be carrying various pathogens, depending on the type of bacteria and the wearer's profession (with doctors and animal care workers being especially prone to contaminated shoes).

Another study suggests up to 96% of shoe bottoms carry E. coli, which means your shoes have come into contact with sneaky feces, even if you can't see it, since that's how E. coli spreads.

There's also some evidence that dust and other filth can allow bacteria to swap genes that help them develop resistance to antibiotics, contributing to so-called "superbugs" that are difficult to treat, New Scientist reported.

You can track in pesticides or lead from the lawn, playground, or garden

Even a well-manicured lawn or fancy playground may not protect your shoes from filth, since outdoor environments can expose your shoes to various chemical toxicants, research suggests.

Weed killer and pesticides can be tracked into the home even a week after the chemicals are applied, one 1999 study found, which can cause health risks like rashes and dermatitis.

Soil can also harbor particles of lead, one of the most well-established environmental health risks, linked to cognitive impairment and neurological damage.

The EPA recommends removing your shoes at the door to prevent lead-laden dirt from making its way into your home.

But sticking to pavement may not help, either — research suggests exposure to asphalt residue either through the skin or via inhalation can be carcinogenic, too.

Shoes are also a source of tiny fragments of plastic that can be absorbed into your body

Microplastics are super small bits of plastic floating around in the environment. New research has found microplastics can be lodged inside the lungs of living humans, although it's not fully clear what the health risks might be.

And shoes are a well-established source of microplastics, which can track the particles not only into your home but also into the natural environment.

"Forever chemicals" can cling to outdoor footwear

Another environmental contaminant that might hitch a ride on your shoes is PFAs, short for per- and polyfluoroalkyl substances. Known as "forever chemicals" because they can linger in the environment and in your body, PFAs exposure is linked to higher risk of some cancers. They're found in some consumer products as well as in air, water, and soil.

PFAs might even be present in your shoes or boots themselves since stain-resistant or waterproof gear is a common sources of PFAs.

It's not clear how dangerous exposure to PFAs through clothing might be, although experts say exposure should be avoided whenever possible.