What a pleasant thing it is to take a bubble bath in winter.

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There was one not long ago? Is bath milk afraid of inducing breast cancer? The rumor was widely circulated in the WeChat circle of friends, and it was proved that there was no scientific basis afterwards. But the controversy surrounding shower gel is far from over. There has been another rumor recently. In an article entitled "Six Things Never to Do in the Bathroom" (or "Six Carcinogenic Bad Habits Committed by Everyone in the Bathroom"), the shower gel was named again. In the so-called? Six bad habits? Among them, bubble bath topped the list.

? Many young women prefer to lie in the bathtub and take a bubble bath instead of taking a bath with soap. Most substances in soap are derived from natural substances. But the foaming agent used in bubble bath is not very fragrant, but this fragrance may cause skin inflammation and dizziness; Lying in the bathtub for a long time makes your body contact with foaming agent, which contains harmful chemicals? Foam stabilizer? It will penetrate into the skin and breathe into the lungs. Expert tip: try to take a bubble bath and use less shower gel as far as possible. Vegetable oil soap is a good choice. ?

This rumor spread on the Internet as early as 20 1 1, and it has been widely circulated in recent years because of the lack of authoritative rumors. Although it is vague, what are the two chemicals it mentions? Smell? And then what? Foam stabilizer? It seems serious.

To find out the truth of the rumor, we must first find out how the shower gel is made.

Shower gel belongs to daily chemical products. As the name implies, its production is inseparable from chemical preparations and chemical processing. The simplest formula of shower gel is composed of water, surfactant, foaming agent, foam stabilizer, preservative, thickener, essence and pigment. Sometimes solubilizer (transparent) or pearlescent paste (opaque) is added according to product requirements. In order to make it feel better, some functional substances such as softener should be added. Most detergents on the market are produced in this way, such as shampoo, detergent and even soap that we may think is more natural.

We often produce three kinds of dirt: oily dirt, solid dirt and water-soluble dirt. Detergent can remove dirt, because its components interact with the dirt attached to it, thus restoring the original appearance of the object.

Simply put, it is like this:

Fabric? Dirt+detergent? Fabric+dirt? wash

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There are many factors that affect decontamination, and the following are the main factors:

1. surfactant structure

2. Hardness of water

3. Mechanical action

4. Fabric type

5. Temperature

6. Foam

Among them, the main decontamination function is surfactant (surfactant refers to a substance that can significantly reduce the surface tension of the solution and change the interface state of the system when added in a small amount). )

In detergents, surfactants are generally used as washing ingredients, but they are also used as auxiliary raw materials in some formulations, which have the functions of emulsification, wetting, solubilization, moisturizing, lubrication, sterilization, softening, antistatic, foaming and defoaming.

Because it can affect the properties of the two-phase interface, it also shows various excellent properties in practical applications, such as emulsification, washing, dispersion, wetting, penetration, foaming, defoaming, solubilization, decontamination, softness, antistatic and so on. Including the rumors mentioned in the article? Foam stabilizer? Function.

Interrupt: most people think that the quality of a washing liquid depends on its foaming effect, but it is not. There is no direct correspondence between the two. In the washing process, low foaming detergent's effect is not bad. But it doesn't mean that foam has no effect in washing. In some cases, foam still helps to remove oil stains. For example, the foam formed by washing liquid can take away the oil droplets washed off the glass surface; Foam helps to take away dust and dirt when scrubbing carpets. In addition, rich foam can give people a comfortable feeling of lubrication and softness during washing. This is also the reason why foam stabilizers are often added to facial cleanser, shampoo and shower gel. Moreover, sometimes the presence of foam can also be used to judge whether the washing liquid is still effective, because fatty oil stains often inhibit the foaming power of the detergent.

After understanding the important role of bubbles, let's take a look at common surfactants.

According to the types of ions: those that can ionize in water to produce ions are called ionic surfactants; Those that cannot be ionized are called nonionic surfactants. Among ionic surfactants, the hydrophilic group with negative charge is called anion surfactant; Hydrophilic groups with positive charges are called cationic surfactants. Amphoteric surfactants are those that decompose into anions or cations according to the pH value of the solution.

Cationic surfactants are rarely used for cleaning. It is mainly used as antistatic agent and fabric softener, and can also be used for mildew prevention and sterilization. Amphoteric surfactants basically do not irritate skin and eyes, mainly betaine derivatives and amino acid derivatives.

Because cationic surfactants are rarely used and amphoteric surfactants are mild, we will focus on the safety of anionic surfactants and nonionic surfactants.

List of common ingredients in shower gel

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The following are the most common representatives of these two categories:

lauryl sodium sulfate

Anionic surfactant is a typical representative of sulfate surfactant, also known AS As, K 12, sodium coconut alcohol sulfate and sodium lauryl alcohol sulfate (are these two names familiar? ), foaming agent, the commodity sold in the market is usually white to yellowish crystalline powder, which is nontoxic, slightly soluble in alcohol, insoluble in chloroform and ether, easily soluble in water, good compatibility with anions and nonionic, good emulsification, foaming, penetration, decontamination and dispersion, rich foam and rapid biodegradation, but its water solubility is not as good as that of sodium polyoxyethylene fatty alcohol ether sulfate (AES for short).

Sodium dodecyl sulfate can be safely used in food. (12) sodium alkyl sulfate? Its content should not be less than 90%(FDA, 172.822,2000). At present, there is no evidence that it causes cancer. Although high dose may irritate the skin, when it is used as foaming agent in general bathroom products, its concentration is limited, and it conforms to the norms of all countries in the world, so you don't have to worry. [ 1]

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Coconut oil diethanolamide (650 1)

Non-ionic surfactant, also known as 650 1, is a yellowish to amber viscous liquid at room temperature, which has the properties of wetting, foaming, foam stabilization, osmotic decontamination, hard water resistance, cleaning and antistatic. Soluble in water, it can form opaque mist solution in water, completely transparent after stirring, completely soluble in different kinds of surfactants at a certain concentration, and completely soluble in low carbon and high carbon alcohols. In the formula of detergent, its main function is to thicken and stabilize foam, and at the same time, it also has the function of preventing suspended dirt from redeposition. Under the synergistic effect of the main active substances, its degreasing power (the ability to emulsify animal and vegetable oils and mineral oils) has been significantly improved.

In the daily chemical industry, 650 1 is widely used in the production of various cosmetics such as liquid detergent, liquid soap, shampoo, shampoo, cleanser and facial cleanser. It can be compatible with all kinds of surfactants. When used with soap, it can enhance the cleaning effect and has good hard water resistance. It can also be used as emulsion stabilizer for cream products. [ 1]

However, it should be noted that diethanolamine and diethanolamine have been proved to have carcinogenic activity. [2]

1997 65438+in February, the national toxicology project undertaken by the National Institutes of Health and the National Institute of Environmental Protection of the United States focused on studying the effects of diethanolamine and three diethanolamines on rats. The experimental results showed that diethanolamine increased the incidence of liver and lung tumors in male and female mice, and also increased the incidence of kidney tumors in male mice.

In the study of diethanolamide, oleic acid diethanolamide containing a small amount of diethanolamine has no carcinogenic signs, while lauric acid diethanolamide has certain carcinogenic activity to female mice, and coconut acid diethanolamide has obvious carcinogenic activity to rats. Because the carcinogenic activity of the product is directly proportional to the amount of unreacted diethanolamine, the project report points out that the carcinogenic activity is caused by the existence of free diethanolamine in the product.

In the United States, diethanolamine is not a corrosive substance specified by the Ministry of Communications, but its high concentration can still cause strong irritation to skin and eyes. Diethanolamine is less irritating to the skin than diethanolamine, and belongs to mild and moderate irritating substances. It is also less irritating to the eyes than diethanolamine, but sometimes it can cause serious irritation. If swallowed, it may cause nausea, abdominal cramps and diarrhea.

Diethanolamine can also react with nitrite or other nitrosating agents to produce nitrosodiethanolamine, which is a carcinogen. Therefore, diethanolamine should not be used in products containing nitrosants.

Although the conclusion of the project points out that diethanolamine and amide containing free diethanolamine have carcinogenic activity, the follow-up research is still going on because of many factors. However, after that, European countries issued cosmetics regulations to the whole world, which strictly stipulated the dosage, quality, formula and storage container of 650 1. [3]

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In order to avoid the carcinogenic problem caused by diethanolamine, are there any substitutes that can ensure safety and strong decontamination?

Daily chemical experts recommend the following three:

①? Monoethanolamide, similar to diethanolamide, is the product of reaction with fatty acids or esters. Coconut oleic acid monoethanolamide is the most commonly used one, and it is an excellent foam accelerator, which is superior to diethanolamide in the viscosity required by the product. But its melting point is as high as 65℃, and it is solid at room temperature, so it is difficult to get transparent products. Moreover, if the dosage is high, the product will be turbid or have a high cloud point;

②? Alkyl amide propyl betaine, such as coconut oil or lauramide betaine, is an excellent substitute for diethanolamide. They can all reach the viscosity required by product composition, and are also excellent foam synergists with low cloud point, easy processing and moderate conditioning effect.

③? Another technique to replace diethanolamide is the hydration colloid method. Hydroxyethyl cellulose and methyl cellulose are commonly used articles, and carbomer is also commonly used, which is an excellent suspending agent for solid particles.

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In addition to the above surfactants and foam stabilizers, other additives can also be added to the detergent to a greater or lesser extent. Such as enzymes, are nontoxic and completely biodegradable; Another example is tripolyphosphate (STTP) commonly used in traditional synthetic laundry detergents, which has been widely criticized for causing eutrophication of water bodies. Another example is fluorescent whitening agent, which is also controversial because of its potential harm to human body; Another example is the essence (that is, what is said in the rumor article? Smell? ), the essence content in the shower gel that meets the national standard is very low. The quality of essence added in detergent is generally less than 1%, so friends can rest assured.

Tadpole Jun talked for a long time and spent a lot of time explaining the ingredient list of detergent. He just wants to tell you that to discuss whether chemical additives such as foam stabilizer in shower gel are toxic, it is necessary to refine a certain kind of specific elements, and it is best to have corresponding Chinese and English names and molecular formulas, rather than simply generalizing.

Moreover, China has strict regulations on the labeling of cosmetic ingredients. Since June 10, skin care products, cosmetics, bath products, etc. , which belongs to the definition of cosmetics, needs to be clearly marked with the Chinese standard names of all the ingredients added in the product on the product packaging for sale in the Mainland. Therefore, consumers can carefully identify the ingredients they don't understand or worry about before buying.

Finally, Tadpole Jun reminds everyone again: For our health, we must buy washing products produced by regular manufacturers that meet the national standards. Shampoo and shower gel produced by regular domestic manufacturers will be marked with the approval of the Ministry of Health after passing the test? Who's wearing makeup? Number; Related products that pass the inspection and are allowed to be imported will be marked? Is the makeup ready for words? No, these can be found on the website of the Ministry of Health, or you can call the local health department for verification.

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References:

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Author: Tadpole Jun