POTENTIALLY HAZARDOUS BACTERIA ARE EVERYWHERE . In the air, in the soil, in the water, and on any surface we touch, including our own body. These are single-celled organisms that can reproduce on their own. And then there are viruses – genetic material in a protein coat that can reproduce only through attachment to host cells (therefore, antibiotics targeting certain structures in bacterial cells do not kill them). Our first line of defense against all this friendly, but not very fun company is soap. We figure out how to use it correctly.
How did the soap appear
While soap is now associated with cleanliness, it hasn’t always been that way. The ancient inhabitants of Mesopotamia were probably the first to produce something like soap from the fat of slaughtered cows, sheep or goats and alkali obtained from wood ash. Soap is mentioned in Pliny the Elder’s Natural History, dated 77 AD. e. He described the soap as a beef tallow lipstick that men applied to their hair.
But our ancestors did not use soap for hygiene, and in mainly for cleansing tissues. Even fans of public baths, the Greeks and Romans, did not use soap to cleanse their bodies, preferring to first relax in hot water and then actively rub themselves with fragrant oils.
In the Middle Ages, soap was already more like what we know it now. It was soft because it contained natural oils, smelled good, and was popular with privileged people. When Aleppo soap to olive oil were brought to Europe from Syria, mylovar here is taken to adopt the technology. Castilian soap has become one of the most popular variations on the theme .
Despite all this, soap was still used with care and was mainly used to wash laundry, not yourself. The situation did not change even after the appearance of large soap factories: Colgate in 1807 and Procter & Gamble in 1837 . But it changed after the Civil War, during which regular washing with water and soap was promoted as a sanitary measure (which it actually was). The first P&G perfumed toilet soap appeared in 1879 , and already in 1898 Palmolive soap was released based on palm and olive oil, which by the early 1900s had become one of the best-selling in the world.
How soap is made
When marketers tell us that soap is made with millennia of technology, they may not even be lying. Recipe of soap, and the truth is not changed , it is used today for all those same fats or oils in combination with alkali and water (various nice additions in the composition is not in the score). When these components are combined together, they go through a chemical saponification process. And, in fact, they turn into soap.
There are two ways to make soap: cold and hot. In the first case, an alkaline solution at room temperature is mixed with animal or vegetable fat, then it is heated as a result of a chemical reaction, and then the soap must be allowed to stand for several weeks to remove excess water. In the second case, everything is a little simpler and faster: the ingredients are heated as they are mixed using an external heat source, after which the soap is poured into molds and hardens after a while.
Why soap washes and cleans
Regardless of which product we use, several factors must combine for cleansing to occur. And hands or something else is already the tenth thing. So, chemical energy is useful (it is provided just by soap or any detergent), mechanical energy (hand movements or a washing machine, for example) and thermal energy (hot water, which washes away dirt better, which is true, however, more likely for clothes).
Water has a high surface tension, so it tends to form a “ball” on different surfaces without interacting with them. To remove dirt from hands or to wipe off a stain on a fabric, there is no way without it, so here surface-active substances (surfactants) come into play. Just like a magnet has two ends, one end of a surfactant is hydrophilic in nature and is attracted to water molecules, and the other is hydrophobic in nature and repels from them.
When a surfactant gets into water, it self-organizes into a sphere with hydrophilic ends on the outside and hydrophobic ends on the inside, which is well known to us as a micelle from micellar water. Water with dirt enters the micelle, but can no longer get out, because the hydrophobic part of the sphere keeps it inside. And then we just wash it all off – it’s done.
Curiously, hand washing became compulsory in medicine quite late – only in the mid-1800s. This happened when a young Hungarian physician Ignaz Semmelweis conducted an important study at the Vienna General Hospital. Disappointed with the study of law, Semmelweis moved on to the study of medicine, graduating from the University of Vienna in 1844 with a medical degree. Denied pathology, he turned to obstetrics, a relatively new field for doctors. And then, of course, he did not yet know that it was here that the finest hour was waiting for him .
The main cause of maternal death in Europe at the time was fever fever , an infection now known to be caused by the bacterium streptococcus. Until 1823 , about one in a hundred women died in childbirth at the Vienna Hospital. But after a policy change that instructed medical students and obstetricians to perform autopsies in addition to their other responsibilities, mortality among young mothers suddenly jumped. Vienna Hospital opened a second branch, staffed only by women, midwives, mortality which in the end turned out to be much lower. The only significant difference between the departments was that male doctors and medical students delivered in the first department and women in the second. As a result, the doctors of the first department, including Semmelweis, were accused of incompetence and fired.
But the research continued. The secret was revealed by Ignaz Semmelweis after the death of his friend and colleague, a pathologist, who cut himself with a scalpel during an autopsy of the patient. The analysis of the pathological picture showed that it is identical to that which was recorded in mothers and babies who died from childbirth fever . So it became obvious that the reason is in the cadaveric particles that are transmitted to women from doctors who are not used to washing their hands after a morgue. After hand washing and bleaching of instruments became mandatory, morbidity and mortality among female patients dropped dramatically.
Do we know how to wash our hands
An analysis of studies around the world promoting soap and hand washing has shown that such campaigns have resulted in a 30 % reduction in diarrhea and respiratory diseases . Sounds good, right? The only thing is that we do not seem to be very good at washing our hands.
This is hinted at, for example, in a 2018 study in which adults over 60 were observed with a camera while cooking. It was found that only 30 % of people washed and dried their hands properly before preparing food. At the same time, almost 90 % of participants were unable to wash and dry their hands properly after interacting with raw chicken, 62 % did not bother to wash the space between their fingers, and 47 % did not use soap.
Can an antiseptic replace soap?
In a pandemic, we are used to carrying antiseptics everywhere , but are they as effective as soap? Scientists give an unambiguous answer: no. Soap and water are better at killing all kinds of microbes, including cryptosporidium and norovirus. And while hand sanitizers, when used correctly, can also neutralize many strains, the problem is that we often do not use them enough or treat our hands completely.
In addition, it is important to consider that antiseptics can work well on slightly dirty hands, but not when hands are very dirty or greasy . At the same time, it is always worth choosing disinfectants with an alcohol concentration of 60 to 95 %, because products in which there is less alcohol do not do the job well in general and rather reduce the growth of bacteria, but do not destroy them.