Antipyretics, preservatives, sunscreens, fluoride toothpaste, surfactants, plastics…
“So what product should I use?”

Professor Kim Beom-jun, author of "The Physics of the World," recommended by science communicator EXO.
A book exploring chemistry closely related to everyday life by mother scientist Yoon Jeong-in.

As soon as I open my eyes in the morning, I ventilate the room, brush my teeth, and wash my face.
I think I have a low fever, so I'm taking some fever reducer.
I put on makeup, get dressed, and leave the house.
Elevators are always fitted with copper antibacterial film.
As soon as I arrive at work, I rub my hands with hand sanitizer and drink a cup of coffee.
In this way, everything we eat, apply, and wear every day is chemistry.
There was a time when there was a craze for 'chemophobia', but after COVID-19, the chemical products we encounter on a daily basis have become much more diverse, from medicines such as antipyretics, painkillers, and vaccines to household items such as disinfectants, detergents, and soaps.
It's hard to imagine living without chemicals these days.


"Chemistry Stories for Worried Adults" is a practical chemistry exploration book that guides adults who experience constant doubt, anxiety, and worry whenever they use chemical products to use them with greater peace of mind and convenience.
Author Jeong-in Yoon, a scientist and mother, wrote this book by gathering the most up-to-date information and chemical knowledge about the most frequently asked questions, the most frequently discussed topics in university classes every year, and the products we use in our daily lives.
From the principles of chemistry to how to use chemical products safely, this book contains essential scientific knowledge for our daily lives. It is a friendly guide to protecting not only your own life but also the lives of your loved ones.

For that reason, it is important to remember that the different types of drugs in antipyretics are acetaminophen vs. ibuprofen (dexibuprofen).
Dexibuprofen is an upgraded version of ibuprofen, so if you give your child ibuprofen and dexibuprofen together, saying that you are taking them interchangeably, your child may suffer from side effects called gastrointestinal side effects such as indigestion, vomiting, ulcer bleeding, and inability to urinate, which could lead to a tragic disaster that requires a trip to the hospital.

--- p.29

There are more things we need to check when purchasing hand sanitizer.
The first is the ingredients.
Currently, the three active ingredients in hand sanitizers are ethanol, isopropanol, and benzalkonium chloride. You should check whether one of these three ingredients is listed as an active ingredient on the back.
This means that one of the three ingredients must be present.
Any other ingredients are not suitable for human use.

--- p.46

We now know that eradicating microbes isn't the best solution.
We now know that excessive antibiotic use has made microbes resistant to antibiotics and is damaging the beneficial gut microbes that already live alongside humans.
Advances in science have made it possible to distinguish between microorganisms that cause disease and those that do not.

--- p.51

In fact, the air quality in enclosed spaces, whether in a laboratory or at home, is not good.
Because humans are breathing animals.
We breathe in oxygen from the air and exhale carbon dioxide.
If you are in a closed space for a long time, you will continue to inhale the oxygen that was present in that space and continue to exhale carbon dioxide.
That is, the concentration of oxygen in that space decreases and the concentration of carbon dioxide increases.
When the concentration of carbon dioxide increases, it can cause drowsiness, and in severe cases, vomiting and headaches.
This is why you feel drowsy when driving for a long time in a moving car without ventilation.

--- pp.61~62

In the past, skin damage caused by sunlight was limited to people living in certain regions or countries and those in occupations with high exposure to sunlight, but now things are different.
In the past, due to the destruction of the ozone layer, and more recently, due to the reduction of atmospheric particles and clouds, much more ultraviolet rays are reaching the earth than in the past.
Therefore, no country on Earth is safe from UV rays anymore.

--- p.73

You may have heard of the terms "weaponless car" and "organic car."
It has been frequently featured in sunscreen advertisements for a while.
Inorganic sunscreens refer to inorganic UV blockers, and organic sunscreens refer to organic UV blockers.
It is classified according to the active ingredients contained in sunscreens. Inorganic sunscreens are made of inorganic compounds that do not contain carbon, and organic sunscreens are made of organic compounds that contain carbon.
These two differ in how they block UV rays.

--- p.75

What is "immunity"? While the word "immunity" is actually found in the Korean dictionary, it doesn't exist in the realm of experts.
The English word 'immunity' is simply translated into Korean as 'immunity'.

--- p.89

This immune system either directly kills pathogens that have invaded our bodies or eliminates infected zombie cells.
Viruses cannot invade the body and reproduce on their own (increase the number of cells).
It can only multiply by parasitizing on someone, and to do this, it infects cells and turns them into zombies. When these infected cells die, the virus inside them is released.

--- p.90

True immunity has a special and very important ability.
It is the ability to accurately distinguish between the allies you must protect and the enemies you must attack.
Because we can accurately distinguish between friend and foe, when pathogens such as bacteria or viruses invade our bodies, we can recognize the enemy and immediately attack and kill them.
The alarm system that is activated at this time corresponds to the immune system.

--- p.91

You can easily find the LD50 table by searching on the Internet.
When looking at this chart, what we should pay attention to are the animals and routes of exposure that were confirmed to be toxic, as well as the intake per kilogram. Since the LD50 represents the amount that would kill an individual if ingested at once, a higher intake per kilogram means a safer intake for the same amount.
According to this table, water is the safest substance, and the most threatening substance to humans is botulinum toxin, which can cause death even in very small amounts, such as 1 ng (nanogram).

--- p.101

First, let's find out what heavy metals are.
Heavy metal means heavy metal.
Among these heavy metals, there are those such as zinc, manganese, and iron that play various roles in the human body, but on the other hand, there are also harmful heavy metals such as lead, cadmium, mercury, chromium, and arsenic that can cause harm to the human body even in trace amounts.

--- pp.107~108

Heavy metals can be easily found in pigments that represent color among art materials.
Early pigments were made by grinding various colored rocks into powder.
In a word, it is like stone dust.
Among the representative colors, there is ultramarine.
It is a mineral called lapis lazuli and has a blue color.
Early paints were made from ground up these minerals, and later oils were used, evolving into modern oil paints.
If you mix it with water, it is watercolor paint, and if you mix it with oil, it is oil paint.

--- p.108

The reason heavy metals are dangerous is that when they enter the body through various routes such as air, water, and food, they are not easily excreted from the body and eventually accumulate in the body.
Representative hazardous heavy metals designated and managed by the Ministry of Food and Drug Safety include lead, cadmium, mercury, and arsenic.
Unfortunately, metals designated as hazardous heavy metals are used in many industries.
Lead is used in automobile batteries, cadmium in paints, and chromium in automobile and portable parts to increase the strength of iron products and to give them a glossy finish.
You can sometimes see metal surfaces being plated with chrome to prevent them from rusting.

--- pp.111~112

These polymers, or plastics, have different properties and are called by different names depending on the type of carbon molecules that are combined.
PE, PP, PVC, as we know them.
Whenever there is an article about the detection of phthalate plasticizers in products used by children, such as children's play mats, toys, bags, and carriers, the polymer that is dragged out and criticized is PVC (polyvinyl chloride).

--- pp.119~120

This fun slime is a representative compound among children's toys that has been controversial for its harmful properties.
Since the issue was first raised in 2018, various media outlets have been enthusiastically portraying slime as a chemical mass, a toxic substance. They've been blaming DIY products, commercially available products, and so on. But when children want to play with slime, the question arises: is it really safe to play with it?
--- p.129

The same goes for fluoride.
There is no need to worry too much when using just the right amount for human benefit.
The fluoride we are exposed to is at very low concentrations, and even in the case of toothpaste, we rinse it with water and spit it out, so the possibility of ingesting it is very low.

--- p.145

The problem is that we've missed the point we should be concerned about.
The focus of concern is on Teflon frying pans, not on the persistent organic compound PFOA.
The toxic substance is not Teflon, but PFOA, a perfluorinated compound.

--- p.151

When you go around to buy daily necessities, you will see phrases that particularly emphasize 'natural'.
You may also see phrases like “from nature,” “100% natural,” “naturally derived,” and “safe because it’s natural.”
Or, even if it doesn't directly say it's safe, there are times when the nuance of safety is already strongly conveyed through phrases like "Contains natural ingredients instead of dangerous chemical ingredients."

--- p.169

When promoting detergents, cleaning products, and cosmetics, the word 'natural' is usually put at the forefront.
Since the recent controversy over sanitary pad toxicity, sanitary pads that claim to use only natural ingredients are also gaining attention.
So, are all natural ingredients safe? I believe the unconditional belief that all natural ingredients are safe is dangerous.
Because not all natural substances are necessarily beneficial to humans.
--- p.170

Some natural products are truly beneficial.
This is because there have been cases where medicines derived from natural products have saved all of humanity.
For those studying natural medicines, the name of this drug, which has great historical significance, is penicillin.

--- p.173

Surfactants are compounds that have both hydrophilic and oil-loving properties.
Because they possess both properties, surfactants can bind to substances of both types.
The most representative characteristic of this substance is that it can mix two substances that seem to be absolutely incompatible.
So how are surfactants used as detergents?
--- p.182

For that reason, humans need to wash frequently.
And at this time, surfactants are absolutely necessary.
Water never washes away germs sufficiently.
To protect the skin, the skin surface is covered with various hydrophobic substances such as dead skin cells, sweat, and sebum.
And there may also be dead bacteria, which are the same hydrophobic substances.
These hydrophobic substances cannot be washed away by hydrophilic water.
There is a reason for that.

--- p.183

The chemical properties of surfactants are not limited to cleaning.
Our cells are surrounded by a thin membrane of phospholipid bilayer called the plasma membrane.
This is what we commonly call the cell membrane, and this cell membrane is in the form of hydrophilic-hydrophobic-hydrophobic-hydrophilic, and it creates a wall like this to prevent internal and external substances from mixing or external invaders from entering.

--- pp.185~186

The problem is that as companies disclose their ingredients, they advertise with no scientific basis whatsoever in an attempt to increase the value of the ingredients they use, or they package their products as if they were effective ingredients when they are not.
There are many cases where cosmetics are promoted as having the effects of medicines, even though they are just cosmetics and not medicines.
In this flood of advertisements, it is important for consumers to know what goes into cosmetics in order to make wise choices.

--- p.194

Medicines and cosmetics actually have the same starting point.
Whether it is an ingredient used in cosmetics or an ingredient used in medicine, they overlap in the large category of chemicals, and among the various chemicals that exist in the world, products that are effective, that is, highly effective, in a certain environment, such as for a specific disease or whitening, are developed as medicines, and if the effectiveness is low but safety is above all else, these are developed as cosmetics.

--- p.197

While Berthollet was conducting experiments to solve this problem, he discovered that when chlorine was passed through lye water, the chlorine dissolved and its toxicity disappeared, while its effect of cleaning the cloth was maintained.
The bleaching agent that Berthollet discovered at this time is a compound called potassium hypochlorite (KClO).
Later, Berthollet discovered that a bleaching substance could be produced by passing chlorine gas through a sodium carbonate solution, rather than lye, and he sold this substance under the name “Zavel water.”
The substance Berthollet created at this time was sodium hypochlorite, the active ingredient in modern bleach.

--- p.203

So where does the distinctive odor of bleach come from? When bleach's main ingredient, sodium hypochlorite, is diluted in water, it undergoes a slight change through a process called ionization.
When sodium hypochlorite with a pH of around 7 to 8 comes into contact with water, the sodium is ionized in the water and becomes hypochlorous acid.
At this point, Rocks really transforms into the role of true Rocks.
Simply using hypochlorous acid or sodium hypochlorite solution does not have an odor.
The distinctive bleach smell after cleaning is actually evidence that the bleach has done its job and killed the bacteria.

--- p.205

It is commonly thought that handmade soap is mild and factory-made soap is toxic.
However, the saponification reaction is a chemical reaction that occurs the same whether it is made in a factory or at home, and the movement of electrons that occurs within it is also the same, so it cannot be said that the mildness or toxicity of soap varies depending on the manufacturing environment.

--- p.212

Some people say that they clean the drain by adding sodium bicarbonate and citric acid together and pouring water into it.
This is incorrect usage.
Sodium bicarbonate and citric acid are a combination of a basic substance and an acidic substance, so when the two are combined, they become water.
The gas produced through the reaction between sodium bicarbonate and citric acid is carbon dioxide.
And this carbon dioxide is what creates the bubbling bubbles.

--- p.222

Although both the earthenware pot and silicone are useful products, they have the inconvenience of requiring more care when washing.
It's because of the residual detergent.
As accidents caused by chemical products occur frequently and are reported, we have inevitably become more concerned about chemicals.
The same goes for any remaining detergent.
Parents are particularly concerned about media reports that surfactants left on children's dishes in the kitchen can accumulate in the body and cause cancer.

--- pp.226~227

Of course, a more important principle is to periodically check for cracks while using it.
I always check the scratch situation after using the children's dishes.
I checked for scratches and replaced silicone or plastic products used by my child, such as baby bottles and eating utensils, periodically. I replaced baby bottles approximately every 6 months and baby eating utensils every year.
In my case, I replaced it because the scratches were visible to the naked eye after using it that much, but since each household's situation will be different, I recommend replacing it after referring to it.

--- pp.228~229

The kitchen is one of the most important places in the home.
We store food, cook food using that food, and consume that food to get energy.
Therefore, this space must be safe from germs and microorganisms.
However, we often overlook this point, which sometimes leads to problems.

--- p.233