Q17: Could I absorb toxic substances through the soles of my feet?

The short answer is no, as that is highly unlikely to happen.

Skin has several purposes, but the main one is to protect the body from outside elements that may do us harm. The skin of the soles of the feet is especially tough and designed to withstand practically anything that we may step on, such as the ordinary dirt and filth on a city street, whatever might be on the floor of a public restroom, or whatever may be on any surface we’re walking on.

Merely touching or stepping on potentially “toxic” substances is not going to cause them to absorb into the body, any more than touching or stepping on anything at all will cause it to enter our bodies. Otherwise, there’s no way we could even exist in this world as humans beings; we’d basically be sponges.

It’s also important to differentiate between something absorbing into the skin (only) and something absorbing through the skin and INTO our bloodstream.

Most liquids will absorb into the outer layer of the skin (epidermis), but usually that’s as far as they will go (moisturizers, Epsom salt soaks, etc., even water). Those and similar substances will not penetrate farther and get into the bloodstream.

The composition of any chemical exposed to skin determines its possibility of entering the skin or going farther, into the bloodstream. This refers primarily to the molecule size and solubility of the chemical. For example, transdermal medical patches work because (1) they are specially formulated by chemical engineering to contain molecules that are soluble in skin as well as small enough to penetrate and absorb into the body, and (2) they must remain on the skin constantly over a long period of time. Hardly conditions to which barefooters’ feet are normally exposed, regardless of where they walk. In addition, medicinal patches need to be placed in the areas of the skin that are most likely able to absorb the medication. The soles of the feet, even disregarding the obvious practical problems of such placement, could never be an effective area to absorb medication through the skin and into the bloodstream.

An internet search for potential skin or bloodstream absorbable chemicals or other substances will reveal results that range all over the place. These range from claims that practically anything that touches our skin will end up in our bloodstream to more reasoned findings that some chemicals and other substances could absorb and penetrate into the bloodstream given certain specific conditions (quantity of the chemical, total time or frequency of exposure, area of the skin, etc.), with the unlikelihood of many other chemicals being able to ever dermally penetrate into the blood stream.

Most claims of various chemical or other substance absorbability into the bloodstream through the skin are based for the most part only on hypotheses, as there are little to no actual scientific studies for those conditions in human beings, and very few involving animals.

Even certain chemicals and other substances with well known toxicity levels that may be harmful to human health if inhaled or ingested (pesticides, chemical fertilizers, etc.) have never been shown to be capable of entering the bloodstream by only skin contact.

The most likely substances that a barefooter’s feet may occasionally come into contact with are trace amounts of leakage from motor vehicles, such as oil, gasoline, etc.; bodily fluids from humans or animals, such as spit, urine, feces, etc.; or dropped or discarded food particles, etc. None of those substances has ever been found to absorb into the bloodstream through skin penetration.

So, absorbing toxic substances through the feet when walking around barefoot is highly unlikely and not something barefooters need to be concerned about.