Lecture
Surfactants (SAS) are among the most important
components of cosmetic products (shampoos, shower or bath products,
shaving foams, toothpastes, etc.). It is known that surfactants are divided into anionic, cationic and nonionic .
Surfactants are capable of causing toxic effects in
humans. They are often allergens. In addition, they interact with the cytoplasmic membrane of cells, depolarizing it. This leads to a change in
membrane permeability for certain substances and its destruction. Let us note,
that the use of the same surfactants in cosmetic products and household chemicals is not permitted. Oral intake of synthetic surfactants (as part of toothpastes, elixirs,
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etc.) and their penetration into the human body even through intact
skin is possible. The rate at which surfactants enter the body depends on their physicochemical properties, concentration and duration of skin contact with them.
It should be noted that under everyday conditions, when using synthetic
detergents, personal hygiene products and perfumery-cosmetic substances, the human body may experience the complex harmful effects of surfactants.
In addition, practically all surfactants used in household chemical compositions are usually able to remove from the surface
of the body all fat-like products, in particular the thin protective film formed by the sebaceous and sweat glands of the hair and skin. This was presented in data
from the Henkel company (Table 4.1) .
Table 4.1 – Dermatological characteristics of some surfactants
Surfactant Degree of skin irritation, rel. units
Sodium lauryl sulfate 68
Disodium laureth sulfosuccinate 5
Fatty alcohol alkyl sulfate 4
Sodium myristyl sulfate 9
Cocobetaine 30
Cocamidopropyl betaine 7
Surfactants affect the structural and functional state of the blood (hemoglobin, erythrocyte and leukocyte counts,
changes in the leukocyte formula). It has been shown that the greatest hemolytic activity toward rat erythrocytes is characteristic of surfactants having
a single polyoxyethylene glycol chain with 16-18 carbon atoms. It has been shown that surfactants also affect metabolic processes
and the activity of a number of enzymes in the animal body. Anionic phosphorus-containing
surfactants suppress the synthesis of certain hormones and enhance the processes of peroxide oxidation of lipids of biological membranes.
Sodium lauryl sulfate (a synthetic surfactant) – is a classic product
that formed the basis of the first shampoos. It has a high irritant effect.
Sodium lauryl sulfate promotes foam formation and is included in almost
all toothpastes and cosmetic cleansing products (mousses, gels, soaps,
shampoos, etc.).
Sodium lauryl sulfate easily penetrates the skin. Traces of it have been found in the heart, liver, lungs and brain of humans, especially in children. It changes the
protein composition of cells, disrupting the structure of the hair follicle, and promotes
hair loss; accumulating in the tissues of the eye, it leads to impaired vision, and also dries the skin, making it rough and promoting the appearance of cracks.
Detergents based on alkyl sulfates and sulfanol have a sensitizing and irritating effect on the human body.
Some of the dangerous surfactants included in
cosmetic products are water-soluble derivatives of ammonia. Indeed, dietha-
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nolamine (4.1) and triethanolamine are practically always present in bath foams,
body wash products, shampoos, soaps and cosmetic cleansing agents .
They are used as thickening, wetting, surface-active and alkalizing agents. They cannot be considered toxic substances. Nevertheless, they readily react with any nitrite and form
carcinogenic nitrosamines, for example, N-nitrosodiethanolamine. For example,
diethanolamine can react with other components in cosmetic products to form nitroso-diethanolamine. Nitrosodiethanolamine is easily absorbed by the skin and causes liver and bladder cancer.
A similar effect arises as a result of the action of cocamide diethanolamine,
diethanolamine lauryl sulfate, lauramide diethanolamine, linoleamide diethanolamine, oleamide diethanolamine, triethanolamine.
Long-term use of most cosmetic
products increases the risk of carcinogen formation. There is data that about 42%
of all cosmetics in the USA, especially shampoos, contain significant amounts of N-
nitrosodiethanolamine. In Europe, the use of secondary
amines in cosmetic products is prohibited.
Industrial methods, namely the addition of ascorbic acid, sodium
hydrogen sulfite, butylated hydroxyanisole, butylated hydroxytoluene, sodium ascorbate and tocopherol to prevent the formation of
nitrosamines in cosmetics, are of little effectiveness.
In addition, it has been established that dimethylaminoethanol (4.2), used in the production of anti-wrinkle creams and other cosmetic products, causes pathological processes in skin cells.
It is believed that under the action of dimethylaminoethanol, some of the skin cells (fibroblasts) increase in size due to the expansion of intracellular cavities – vacuoles. It is precisely this property of dimethylaminoethanol, according to the developers of cosmetic products, that accounts for the wrinkle- and fold-smoothing effect. It is known that dimethylaminoethanol leads to a temporary increase in the size of fibroblasts,
but its action is not limited to this. Over the course of the next several hours,
there is a sharp slowdown in the metabolism and rate of division
of fibroblasts, followed by the death of a significant portion of them.
It has been established that at concentrations of dimethylaminoethanol similar to the concentrations of this substance in cosmetic creams, when applied
to the skin, during the first 24 hours, up to 25% of
cells die in model systems .
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