Here is a useful lexicon to better understand the vocabulary of cosmetics.
Active cosmetic ingredient: Ingredient present in a cosmetic product responsible for the product's effectiveness by performing a specific action on the skin.
Alpha-hydroxy acid (A.H.A.): Family of molecules often used in cosmetics as a soft peeling. It has a surface action by gently peeling dead and dehydrated cells from the skin's surface that can clog pores. AHA's can be of synthetic or natural origin (also known as fruit acids). The most commonly used are glycolic acid (sugar cane, beet, grape), lactic acid (milk), citric acid (lemon), malic acid (apple) and tartaric acid (wine).
Acne: Chronic inflammatory skin disease of the pilosebaceous canal that evolves in flare-ups. It appears when three things are simultaneously involved: hyperkeratinization, hyperseborrhea and bacterial proliferation. The lesions associated with acne can be of two types: retentional (comedones or microcysts) or inflammatory (papules, pustules or nodules). The most common form is juvenile acne, which is generally located on the face, but also, in the most violent cases, on the neckline or upper back.
Agence Nationale de Sécurité du Médicament et des Produits de Santé (A.N.S.M.): This is a public institution affiliated with the Ministry of Health. Consisting of experts, it works to ensure the safety of drugs, medical devices, biological products but also cosmetics intended for human beings.
Alopecia: Scattered or localized, acute or chronic, partial or total loss of either head hair or body hair. This hair loss can have several origins: heredity, stress, dietary deficiency, unsuitable shampoo, etc... The ultimate stage of alopecia is baldness.
Androgen: Male sex hormone secreted by the testicles and adrenal glands located above each kidney. Testosterone is the most active androgen. Women also secrete androgens in small amounts from the ovaries. It stimulates or controls the development and maintenance of male characteristics, such as the development of hair and the male genitalia, the growth and normal functioning of the prostate, etc. On the skin, androgens stimulate the secretion of sebum.
Anti-fungal: Ability to destroy fungi or to prevent their development.
Antiseptic: A product used to oppose the multiplication of microorganisms such as bacteria, viruses or fungi, thus preventing skin and mucous membrane infections.
Antioxidant: Substance that slows down or prevents the oxidation process by neutralizing the free radicals that attack the body's cells. Antioxidants therefore help fight skin aging and dullness, and protect cells from oxidation damage.
Astringent: The ability to tighten tissues and thus make the pores of the skin less visible. This also limits the secretion of sebum.
Atopy: A genetic predisposition to develop hypersensitivity reactions due to a disproportionate immune response. Atopy manifests itself in different forms: eczema, asthma, atopic dermatitis, hay fever, etc…
Atopic dermatitis or eczema: Chronic inflammatory disease of the skin, characterized by a cutaneous dryness accompanied by redness, prurits, scales, crusts etc.
Bacteria: Single-celled microorganism without a nucleus (prokaryote). In the skin, some bacteria are responsible for diseases (pathogenic bacteria), but most are harmless or even in symbiosis with our body (bacterial flora).
Beta-hydroxy acid (BHA): A family of active ingredients with a more in-depth action. In fact, they are used to deeply clean the pores of the skin, where there is an accumulation of sebum, dead skin and pollutants. The most commonly used is salicylic acid (willow).
Balsam: Face and body care with a very rich texture with a consistency that is more oily and thicker than a cream. It is notably composed of oils, waters but also of butters or vegetable waxes. The balsam makes it possible to nourish the skin in-depth thanks to the many lipids which it brings and takes part in the regeneration of the hydrolipidic film.
Bio/Organic: Term relating to a product resulting from the organic agriculture, and which consequently does not use any chemical component of synthesis like the pesticides, the chemical herbicides, the artificial fertilizers, the GMO, or the hormones of growth. It is therefore part of a global vision of sustainable development in respect of the environment. The presence of labels on the product (AB, Cosmebio, Ecocert, etc...) guarantees that the product is organic.
Blush: Colored substance that is applied to the cheekbone to enhance the skin tone. It is found in different forms: powder, cream, gel or liquid.
Brown spot: Pigmentation condition causing the appearance of dark areas of varying size on the skin. These spots are related to an abnormal overproduction of melanin and its uneven distribution. They are mainly caused by frequent or intense exposure to the sun's UV rays. However, hormonal changes, resulting from e.g pregnancy , can also be responsible for this phenomenon. Similarly, the risk of hyperpigmentation also increases with cell aging and is generally visible on the areas most exposed to the sun over time (face, hands, neck, shoulders, neckline, men's skull, etc.).
Bronzing powder or bronzer: A makeup product that is used to enhance the complexion, to give a healthy glow, to imitate the effect that the sun causes on the skin by creating the illusion of a luminous and natural tan on the face. In addition to giving a light tan, it will allow to recreate the natural reliefs (shadows and volumes) of the face.
Cell: Basic functional and structural element of all tissues and organs of the human body. Its core contains the genetic material of the human being. Each cell operates independently but in harmony with all the others.
Cellulite: Local accumulation of subcutaneous fat in certain areas of the body. The skin has a padded appearance, called "orange peel". It occurs almost exclusively in women.
Cellular renewal: The dynamic process of natural regeneration of the skin. It consists of the production of new cells to replace those that have died and been shed in the form of flakes. The normal cycle is 28 days, which is the time required between the creation of a cell and its migration to the horny layer. However, this time increases with age.
Ceramides: Lipidic compounds naturally present in the intercellular cement of the skin. They account for 50% of the skin's composition. Ceramides maintain the cohesion between cells and form a protective layer, preventing water from evaporating and irritating substances from penetrating the skin.
Carcinogenic, Mutagenic or Reprotoxic (C.M.R.): A term derived from the regulations on the prevention of chemical risks for substances that have various harmful effects on human health in the mid to long term through inhalation, ingestion or skin penetration. Thus, some of them can be :
Carcinogenic: Dangerous chemical substance. This substance, alone or in a mixture, can cause cancer or increase its risk (e.g. asbest, benzene, etc.);
Mutagenic or genotoxic: A chemical substance that can induce genetic alterations or increase their risk;
Reprotoxic (toxic to reproduction): A chemical substance (e.g. lead) that can impair reproductive functions or capacities and cause adverse effects on one's offspring (spontaneous miscarriage, malformation, etc...).
Due to the dangers they present, these substances are subject to restrictive regulations.
Cleanser: Care that cleanses the skin and removes impurities attached to the surface: makeup pigments, traces of pollution, toxins released by the skin and dust.
Collagen: Protein naturally present in all structures of the body: skin, cartilage, tendons, ligaments and connective tissues. It is the most abundant protein in the human body. In fact, it represents 30 to 35% of the body's total proteins. Produced by the fibroblasts of the dermis, collagen plays a structural role for the skin and provides firmness, elasticity and suppleness to the skin. However, with age, its production deteriorates.
Comedogenic: Term referring to a product that tends to cause the formation of blackhead-type imperfections by clogging the skin's pores. Sebum accumulates, bacteria proliferate and imperfections appear.
Comedo: Small cluster of sebaceous material that is either whitish (closed comedo) or black (open comedo). When in contact with the air, it oxidizes and blackens at the level of the skin's pore. It appears as a result of an excessive accumulation of sebum that clogs the opening of the pilosebaceous ducts. When it persists or worsens (bacterial infection), it can develop into acne.
Compact powder: Make-up product generally colored which brings a certain coverage. It is the equivalent to foundation but as a "solid" powder. It allows to hide dilated pores, to blur imperfections, redness and dark circles for a smooth and unified result.
Complexion: Coloration, appearance, shade and radiance of the face.
Contouring: A makeup technique for redesigning the face by playing on dark/light optical effects. Thus, it allows to correct, attenuate, remodel and sculpt certain facial features by creating shadowy areas with a bronzing powder and light areas obtained with an illuminator. The principle of contouring is to conceal certain small flaws, to refine parts of the face that are considered unflattering (double chin, forehead too wide, size of the nose, face too round, etc.), while enhancing other parts that are not considered imposing enough.
Cortex: This is the middle and thickest layer of the hair shaft, responsible for pigmentation and most of the physical properties of hair (strength, flexibility, elasticity and direction of growth). The cortex is composed of keratinocytes rich in keratin and also containing the pigments that provides your hair with color (melanin). The cortex is protected by the cuticle.
Cosmetic: "All non-medicated substances or mixtures intended to be placed in contact with the superficial parts of the human body (skin, hair, nails, lips and external genitalia) or with the teeth and oral mucous membranes, with a view, exclusively or principally, to cleaning them, perfuming them, modifying their appearance, protecting them, maintaining them in good condition or correcting body odors", according to the European Cosmetic Regulation n°1223/2009.
Cosmetic allergen: Substance likely to induce a reaction known as sensitization in an individual. An allergen presents a risk to sensitized individuals. The hypersensitivity reaction then results in an inappropriate immune response leading to redness, swelling, itching, etc. Allergenic molecules originate from perfume, essential oils and/or plant extracts. The European Cosmetics Regulation requires 26 of them to be declared in the product's list of ingredients, as soon as they are present at more than 0.01% in rinse-off products and at more than 0.001% in leave-on products.
Cosmetology: Science studying the preparation and use of cosmetic products.
Cosmetovigilance: A strict monitoring and recording system of adverse or serious events (redness, burning, rash, etc...) attributable to the use of cosmetic products imposed by Regulation 1223/2009. This consists of :
Collecting information about the adverse reaction;
Evaluate whether this effect is attributable to the product;
Managing and preventing the occurrence of other adverse reactions.
This activity is mandatory and allows us to ensure the safety of cosmetic products after they are placed on the market.
Cutaneous microcirculation: The blood and lymphatic network structure of capillaries, arterioles and venules, located at the level of the dermis and the hypodermis. It is involved in skin homeostasis (transport of gasses, nutrients, waste), thermoregulation, as well as in the maintenance of blood pressure and inflammatory response. However, skin microcirculation is modified during skin aging, where a progressive decrease in the formation of new vessels can be observed, leading to skin paleness, alopecia, skin ischemia, etc...
Corneal layer or stratum corneum: The outermost layer of the epidermis consisting of dead cells (corneocytes) resulting from the process of differentiation of the majority cell type in the epidermis: the keratinocytes. It is thus in direct contact with the surrounding environment. The thickness of the stratum corneum varies according to the location; for example, it is very thick on the soles of the feet.
Couperose: Permanent redness located on the center of the face (cheeks, nose, chin and forehead). It is linked to the dilation of blood vessels.
Cream: Cosmetic product that moisturizes the skin and prevents its dehydration by reconstituting the hydrolipidic film.
Dark circles: Modification of the skin tone under the eye. Often due to a lack of sleep, dark circles give the eyes a tired and aged appearance. This phenomenon can be accentuated by a depression of the area: we then call it "hollow rings".
Dandruff: Clusters of dead skin that detach from the surface of the scalp and spread through the hair. In some cases, dandruff can be accompanied by itching and irritation of the scalp. There are two types of dandruff:
Dry dandruff, which is fine, whitish, sometimes associated with itching, and falls on the shoulders.
Thicker, stickier, yellowish dandruff, associated with an oily scalp and hair (overproduction of sebum by the sebaceous glands), accompanied by inflammation and itching of the scalp, and which can cause hair loss over time.
In these two situations, these scales are correlated to certain factors, leading to an accelerated renewal of epidermal cells, such as the excessive proliferation of a fungus on the scalp called Malassezia, a hypersecretion of sebum, as well as external factors (stress, fatigue, pollution, certain illnesses, certain medications).
Deodorant: A cosmetic product that is intended to limit or mask unpleasant body odors related to perspiration, as well as to eliminate the bacteria naturally present on the skin's surface that cause them.
Dermabrasion: Intervention consisting in mechanically "wearing down" the upper layer of the epidermis. It is used to remove scars, medium-deep wrinkles, pigment spots or blotches.
Dermatosis: Designation of all affections of the skin and the mucous membranes.
Dermis: One of the three layers forming the structure of the skin, located between the epidermis on the surface and the hypodermis in depth. It is a connective tissue that is mainly composed of an extracellular matrix produced by fibroblasts, the main dermal cell population and responsible for the synthesis of the skin's structural proteins (collagen and elastin fibers). It has an average thickness of 1 to 2 mm: it is thicker on the palms of the hands and soles of the feet (3 to 4 mm) and thinner on the eyelids (0.6 mm). The dermis contains pilosebaceous follicles, eccrine and apocrine sweat glands, nerves, nerve endings, blood and lymphatic vessels, and immune system cells (macrophages, mast cells, etc.).
Desquamation: Phenomenon of spontaneous elimination of the superficial layers of the skin or scalp. The cells are detached in the form of scales, more or less large, often invisible to the naked eye. This mechanism is correlated to the permanent renewal process of the skin. In excess, it can be pathological.
Dilution: Operation allowing to obtain a solution of lower concentration than the initial one by adding a solvent.
Distillation: Separation process which allows to extract essential oil and hydrolat by steam. The idea is to bring the water containing a part of the plant (leaves, flowers, etc...) to a boil. The water then evaporates and carries with it the aromatic compounds of the plant, the steam is then condensed into liquid. One then obtains 2 parts: one aqueous (the hydrolat) and the other qualified as "oily" (the essential oil).
Dull: A criterion used to define a face that no longer reflects light, lacks radiance, freshness and uniformity, and is often grayish.
Ecocert: Independent certification organisation that evaluates the conformity of a product according to environmental and social requirements in a set of specifications. They were the first to develop a standard for "Ecological and Organic Cosmetics".
Elasticity: Physical ability of a body to return to its original shape after being deformed. It is ensured by a network of fibrous tissues that cross the dermis.
Elastin: An essential protein of the extracellular matrix of the dermis responsible for tissue elasticity. Like collagen, it is produced by fibroblasts.
Emollient: Formula which has the particularity of moisturizing, relaxing the biological tissues and softening the skin.
Extracellular matrix (ECM) or intercellular cement: A highly organized network of protein and carbohydrate macromolecules (collagen, proteoglycans, elastin and glycoproteins) that bind cells together and organize them into tissue. In fact, this complex structure surrounds the cells that synthesize it and in turn determines their phenotype. The extracellular matrix thus plays a role in structural support, adhesion, movement and regulation of cells.
Emulsion: Heterogeneous mixture of two fluids that are normally non-mixable. The addition of an active ingredient (emulsifier) causes them to blend together. For example, a cream is an emulsion because it is the result of a mixture of water and oil bound by a surfactant.
Emulsifier: A substance used to mix two immiscible liquids.
Endocrine disruptor: An exogenous substance or mixture possessing properties capable of deregulating the hormonal system of living organisms (thyroid, pituitary, testicles, ovaries, pancreas, etc...), thus causing harmful effects on health. In most cases, they act by mimicking certain hormones such as estrogens. These compounds potentially affect many functions, including reproduction and thus affect fertility or disrupt the development of the fetus, the nervous system, metabolism, etc. .... In cosmetics, these are parabens, phthalates, alkylphenols, phenoxyethanols, etc...
Epidermis: Part of the skin, located above the dermis and hypodermis. Keratinocytes make up 90-95% of the epidermal population, but other cells are also present such as melanocytes, Langerhans cells and Merkel cells. It contains no blood vessels or lymphatic vessels, but has many free nerve endings. The primary function of the epidermis is to produce the stratum corneum which forms a semi-permeable protective layer on the surface of the skin, preventing water loss, constituting the first defense against external aggressions and maintaining a satisfactory hydration of the skin. The epidermis is organized into several cellular layers: the basal layer (stratum basale), the spiny layer (stratum spinosum), the granular layer (stratum granulosum) and the corneal layer (stratum corneum). In fact, the keratinocytes proliferate in the basal layer and then gradually differentiate to form these different epidermal layers by migrating from the depths to the surface where they shed. This differentiation cycle takes 28 days.
Epilation: Controlled, temporary or permanent destruction of hair. It can be done using various conventional methods: tweezers, razor, electric epilator, traditional oriental hair removal, depilatory cream, waxing, etc...
Erythema: A common dermatological lesion that manifests itself as a congestive redness of the skin, diffuse or localized, more or less intense, which fades with vitropression.
Eye contour: The thinnest, most sensitive and most fragile area of the face around the eye (mobile eyelid, corner and under the eye) that needs specific care.
Essential oil or plant essence: A hydrophobic liquid concentrated in odoriferous compounds, usually extracted from an aromatic plant (flower, root, leaf, etc...), after separation of the aqueous phase by physical processes: either by steam distillation, dry distillation, or by a suitable mechanical process without heating. These methods of extraction make it possible to concentrate the aromatic molecules of the plant insoluble in water and its active principles. In other words, it is a complex mixture of various molecules such as terpenes, phenols, ketones, esters, aldehydes, etc....
Excipient: Designation of any neutral substance, other than the active ingredient, in a cosmetic or medicine to serve as a carrier or support. Indeed, its addition is intended to allow the active ingredient to reach where it is supposed to act. It is also what gives the product a particular consistency (galenic) or other specific physical characteristics (taste, color, etc...), while avoiding any interaction, particularly chemical, with the active ingredient. In cosmetics, the excipient is the ingredient or combination of ingredients that is the most important by volume in relation to the active ingredient, and is generally at the top of the I.N.C.I. list. The most commonly used are water, floral waters, vegetable oils, synthetic oils (mineral) and alcohol.
Exfoliant: Something that removes dead cells from the epidermis. A substance that removes dead skin cells from the epidermis. The process of exfoliation can be mechanical (scrubbing) or chemical, in which case it is called a peel.
Eyeliner: A very precise tool used to underline and define the eyes.
Eyeshadow: Cosmetic product that allows to sculpt, to give depth, to intensify or on the contrary to soften the look. However, this makeup requires a well-defined application technique and procedure. It can be applied as a powder, pencil or cream.
Fibroblast: Star-shaped cell of the dermis responsible for producing the components of the extracellular matrix, notably collagen, elastin and hyaluronic acid.
Filmogenic: Refers to a substance that forms a film on the skin, hair or nails. Unlike occlusive agents, they allow the skin to "breathe" and are less effective over time. Among the film-forming agents, we have beeswax, collagen, hyaluronic acid, etc...
Filter (chemical or organic): A synthetic molecule that must be absorbed by the skin to be active and protect against UV rays by absorbing their energy. It becomes operational, 20 to 30 minutes after application. There are 25 chemical filters authorized on the market.
Filter (mineral or physical): Microscopic particles of natural origin that form a protective layer on the surface of the skin to reflect the sun's rays. There are currently two types: titanium dioxide and zinc oxide. Unlike chemical filters, mineral filters are immediately active upon application.
Foundation: A colored makeup product intended to even out skin tone and camouflage imperfections. It can be matte, powdered, satin or liquid. Contrary to a tinted cream, the foundation does not make it possible to hydrate the skin.
Foam: Dispersion of a compressed gas in a liquid in the presence of an emulsifier and a foam stabilizer. In fact, the whole mixture is stabilized by a surfactant which is placed at the interface between the gas and the liquid.
Free radical or reactive oxygen species (R.O.S.): Particularly unstable and very reactive chemical species. A free radical or reactive oxygen species has one or more unpaired electrons on its outer layer and will therefore try to "oxidize" other molecules by subtracting an electron from them in order to stabilize itself, thus making the other molecules unstable in return (oxidation reaction). These species are beneficial for the body, because they are for example useful to defend against infections. However, in case of high production, they can become harmful for the body, because they alter the proper functioning of cells and thus cause tissue damage. In the skin, free radicals destroy skin cells, which leads to skin aging. Various biotic and abiotic cellular stresses can considerably increase their production: pollution, unbalanced diet, tobacco, sun, pathogen attacks, etc... However, they can be neutralized by antioxidant molecules, thus protecting cells from free radical damage.
Fluff: Very fine, short, non-pigmented or slightly pigmented hair, less than 40 micrometers in diameter.
Galenic form: Condition under which the active ingredients and excipients (inactive materials) are put to form a cosmetic or pharmaceutical product, i.e. the physical appearance and texture of a final cosmetic product. In addition, each type of cosmetic galenic has one or more actions that are specific to it. In cosmetology, there are many galenic forms that we can group into three main categories:
Dispersions: emulsions (moisturizing cream, cleansing milk), foams, aerosols (thermal water, deodorant), suspensions (nail polish, foundation);
Anhydrous forms: balms, powders (eye shadow), oils, ointments;
Aqueous forms: gels, colloidal solutions (serum, micellar water), true solutions (lotion, floral water).
Hair: Long hair of variable color originating from a hair follicle on the skull and composed of keratin. The diameter of a hair varies, depending on age and genetic factors, from 40 to 100 micrometers.
Hair bulb: A rounded structure at the base of the hair follicles under the scalp. It is at this level that the hair is made. It grows from the root about 1 cm per month.
Highlighter: A makeup accessory used to highlight certain areas of the face to make them appear brighter. Thus, to capture and fix the light, it is advisable to apply the highlighter on the top of the cheekbones for a natural glow effect, the bridge of the nose to refine the nose, the arch of the eyebrow for a more defined impression of eyebrows, in the inner corner of the eye to enlarge the look and the cupid's bow to simulate full lips. This product comes in different forms: cream, powder, stick, gel, liquid.
Hormone: A active chemical substance produced by the endocrine system in response to stimulation and capable of acting at very low doses. The hormone is distributed throughout the body by blood or lymphatic routes, and is intended to act remotely on specific receptors of one or more target cells in order to modify their function. It therefore acts as a chemical messenger within the body by transmitting information from one organ to another. The messenger molecule is involved in many processes, including growth, reproduction, sexual function, sleep, hunger, cell differentiation, mood and metabolism.
Humectant: Substance capable of attracting water to the skin. Among humectants, we find hyaluronic acid, glycerol, polyethylene glycol (P.E.G.), etc...
Hydrating: Refers to a substance with the ability to increase and maintain the water content of the epidermis. This phenomenon can be obtained through the use of humectants, film-forming agents, occlusive agents or emollients contained in cosmetic products.
Hydrocarbon: Organic compound made up exclusively of carbon (C) and hydrogen (H) atoms.
Hydrolat or hydrosol: Aqueous condensation extract obtained at the end of the distillation process of essential oils from raw plant materials. Unlike essential oils, hydrosol contains a very small quantity of aromatic compounds, most of which are insoluble in water, and is therefore milder. It is a good alternative for sensitive skin, pregnant women and children. Concentrated in water-soluble aromatic molecules, this water helps to purify, soothe and tone the skin.
Hydrophilic: Property of a compound that has an affinity for water and tends to dissolve in it.
Hydrolipidic film: A protective acid pH film that covers the entire surface of the skin, corresponding to an emulsion of water and fat. It is essentially composed of sweat, sebum, water from the deep layers of the skin and other lipids. Its role is to act as an external protective barrier against the development of micro-organisms and external aggressions. It also allows the epidermis to keep suppleness, radiance and hydration.
Hydrophobic: Characteristic of a molecule that is insoluble in water; a substance that is not affine to water.
Hydrosoluble: Characteristic of a molecule that is soluble in water or in an aqueous medium.
Hydrotrope: Ingredient capable of increasing the solubility of a substance that is originally poorly soluble in water, such as ammonium xylenesulfonate, dodecyldimethylamine oxide, etc...
Hygroscopic: Said of an active ingredient that tends to retain water by absorption or adsorption, of which the following are some examples: hyaluronic acid, glycerin, etc...
Hyperkeratosis or keratosis: Abnormal thickening of the corneal layer of the epidermis due to an accumulation of epithelial cells. It can appear in the case of warts, psoriasis or eczema for example.
Hyperpigmentation: Term used to describe the exaggerated development of more or less dark spots, localized on the whole body. It is linked to an excessive production of melanin by the skin. Exposure to the sun is the main cause, but hormonal variations, age, genetic predisposition or skin trauma (acne scars for example) can also trigger their appearance.
Hypopigmentation: Partial or complete loss of melanins within the skin, thus contributing to a decrease in pigmentation of the epidermis. Whether hereditary or not, there are many causes of skin hypopigmentation: vitiligo, albinism, Menkes' disease, depigmentation due to physical agents (UV, X-rays, burns, etc.), Bourneville's tuberous sclerosis, etc...
Hyperseborrhea: Refers to a condition in which sebum is produced in excess by the sebaceous glands making the skin oily.
Hypoallergenic: Refers to a product whose composition minimizes the risk of allergies.
Immediate Pigmentation Darkening (I.P.D.) Test to calculate the UVA protection index. It measures the pigmentary response immediately and up to 15 minutes after exposure to a dose of UVA irradiation. It is a transient pigmentation of the skin, which appears quickly after exposure to UVA. The UVA protection factor is calculated as the ratio of the radiation doses required to produce the pigmentation with and without sunscreen products applied to the skin. Sunscreen products must have a S.P.F./UVA index ratio of less than 3, ensuring effective and balanced UVA protection.
Immune system: A biological surveillance and defense system that is in constant operation. Its mission is to protect the body from external aggressions and internal dysfunctions.
I.N.C.I. List (abbreviation of "International Nomenclature of Cosmetic Ingredient") or list of ingredients: Official international nomenclature that lists all authorized ingredients used in cosmetic products with their legal name. Its presence on the packaging of each cosmetic is mandatory. This list details all the elements of the formula in Latin for natural ingredients or in English for chemical molecules. Nevertheless, the manufacturer is not obliged to indicate their concentration next to each of them because of the "manufacturing secret". However, these elements must be classified in descending order of their quantity for those dosed at more than 1%. On the other hand, below 1%, the manufacturer can make it appear in the order which he wishes.
Inflammation: First line immune defense mechanism of the human body in response to an aggression (wound, infection, burn, allergy, etc.), characterized by 5 clinical signs: pain, heat, swelling (edema), loss of function and redness. Its purpose is to isolate, destroy or inactivate and eliminate all foreign substances, and also to prepare the ground to allow the repair of the damaged tissue.
Inflammation: First line immune defense mechanism of the human body in response to an aggression (wound, infection, burn, allergy, etc...), characterized by 5 clinical signs: pain, heat, swelling (edema), loss of function and redness. Its purpose is to isolate, destroy or inactivate and eliminate all foreign substances, and also to prepare the ground to allow the repair of the damaged tissue.
Ingrown hair: Hair that twists and grows back under the skin because it fails to break through the skin barrier and emerge through the hair follicle opening, often causing redness and inflammation.
Insensible water loss (IWL) or insensible perspiration: A mixed phenomenon composed of passive water diffusion and perspiration, leading to the constant and imperceptible evaporation of water contained in the dermis on the skin's surface. This insensitive diffusion through the epidermis is essential to the normal functioning of the skin, since this physiological process favors the hydration of its superficial layers and also allows nutrients to rise from the dermis to the epidermis. During normal activity, this loss amounts to 300 - 400 mL per day. This evaporation, invisible to the eye, should not be confused with perspiration, which forms micro-droplets on the surface of the skin.
Invigorating: Giving energy, tone, invigorating.
Keratin: A fibrous, water-insoluble protein that is a component of the epidermis, nails, hair, tooth enamel and body hair. Manufactured by keratinocytes, it ensures the protection and impermeability of keratinocytes from external agents. This protein is also important for the cohesion and integrity of the epidermis.
Keratinization or keratogenesis: Continuous process of differentiation and migration of keratinocytes to give rise to the superficial cells of the skin, nails and hair.
Keratinocyte: Cell constituting the epidermis, responsible for the synthesis of keratin as well as lipids that make the skin impervious. The keratinocyte is born at the base of the epidermis, in the basal membrane, before joining the stratum corneum after having crossed several layers in the epidermis. It plays an essential role in protecting the skin against external aggressions, in particular against UV radiation. It also guarantees the impermeability of the body.
Keratolytic: Describes an agent that helps to soften the epidermis to promote its desquamation. It acts upon simple contact with the skin by interacting with the keratin. We have for example salicylic acid, A.H.A. (glycolic acid, malic acid, etc...), urea, etc...
Lipid: An amphipathic molecule, i.e. having at the same time a hydrophobic field and a hydrophilic field, made up of fatty acids. It is characterized by its insolubility in water and by its solubility in non-polar organic solvents. Within the body, the lipid has major roles: it participates in the structure and function of cell membranes and also provides various biological functions, including cell signaling, storage of metabolic energy, in the synthesis of hormones, in the absorption of fat-soluble vitamins or in thermal insulation.
Lipophilic: A term that characterizes the chemical affinity of a material for lipids.
Liposoluble: Description of a chemical body that has the property of being soluble in fats.
Lipstick: Make-up product enriched with pigments or pearlescent agents intended to emphasize the lips by coloring them or to give a shiny effect to the mouth.
Loose powder: A translucent or tinted, light and volatile makeup product that contains mostly mineral powders such as talc, and is used to mattify and fix makeup. It is ideal for combination to oily skin types and contains substances that absorb excess sebum, making it an excellent mattifying powder.
Lotion or tonic: Transparent or translucent liquid, consisting of a single phase with low viscosity, used to clean, purify, refresh and tone the skin. Indeed, in the beauty routine, the step of the lotion intervenes after the make-up removal and allows to perfect the cleaning of the skin. It also prepares the skin to receive the treatments applied afterwards for better penetration.
Lymph: Clear biological liquid, circulating in the lymphatic system. It plays an important role in the body's immunity by transporting immune cells (lymphocytes, macrophages, etc.) to enable the body to fight infections. Lymph also drains excess fluid and cellular waste, and transports dietary fats and fat-soluble vitamins (A, D, E and K).
Make-up remover: Refers to a beauty product designed to remove traces of makeup, dust, cellular debris, sweat and sebum from the skin surface. In the form of oil or emulsion, make-up removers contain lipids to capture lipophilic impurities and make-up residues.
Mascara: Cosmetic product used to make up the eyelashes by coloring them and giving them more length or apparent thickness in order to intensify the look.
Mask: A facial treatment with a concentrated formula that typically requires a few minutes of application time. While most cosmetic masks are rinsed off, others are left on overnight. It helps maintain the skin by providing all the elements and active ingredients it needs to deeply treat specific skin concerns and rebalance all skin types. This ritual care also acts as a complement to daily care to reinforce their effectiveness.
Matifying: Term qualifying a product or an active ingredient that has the property of reducing the shiny appearance of the skin, by absorbing excess sebum and controlling its production.
Melanin: A pigmentary substance that gives skin, hair, hair, and eyes their color. There are two chemically distinct types of melanin in epidermal cells:
Eumelanin, which is a black to brown polymer;
Pheomelanin, which is a red to yellow monomer.
The concentration and the type of melanin are the two main factors at the origin of the diversity of colors of the skin, the eyes and the hair. Their synthesis depends on several factors such as genetics, age, environment, hormones, etc... In addition, under the action of UV radiation, the production of melanin is stimulated: this is tanning, thus playing a role of natural sun shield.
Melanocyte: Cell located in the basal layer of the epidermis, responsible for the pigmentation of the skin by the secretion of melanin. These brown pigments are synthesized in melanosomes, intracellular organelles specific to melanocytes, which are then transferred to the surrounding keratinocytes to color them. Each melanocyte distributes its melanin to 36 keratinocytes. Although it is the cause of tanning, the melanocyte colors the skin to protect it from the harmful effects of UV rays and thus prevent the development of skin cancers.
Melasma or chloasma: A form of hyperpigmentation particularly common in women, especially during pregnancy. It appears as large, dark patches, mostly on the face, especially on the bridge of the nose, cheeks and forehead. Other parts of the body can also be affected such as the décolleté, the neck, etc... Melasma is caused by an increase in melanin synthesis. This overproduction generally occurs in reaction to hormonal changes, for example during pregnancy, following the use of a contraceptive pill or hormone replacement therapy, but also in case of prolonged exposure to the sun.
Micelle: Spherical aggregate made up of a bundle of amphiphilic molecules whose nonpolar faces are turned towards the interior of the micelle and the polar faces towards the outside in suspension in a liquid. Depending on the polarity of the solvent, we speak of:
The micelles are called "direct" when they are in an aqueous solution, such as water, and where the core is composed by the hydrophobic tails of the amphiphiles and the internal region is a crown containing the hydrophilic chains.
Micelles are called "reverse" when they are in an organic medium, such as oil, and whose assembly is made up of hydrophobic chains gathered at the heart of the micelle and the hydrophilic polar heads oriented towards the outside.
Milk: In cosmetics, a milk designates a fluid emulsion "oil in water", i.e. it is not very loaded with fatty substance with a share in water more important than in a cream. It has a rather liquid and very light texture, which penetrates very easily in the skin without leaving an oily film. This product makes it possible to nourish and hydrate the skin.
Mist: Water spray rich in active ingredients to refresh and gently moisturize the surface of the skin, the face or body. It also protects the epidermis from external aggressions.
Microbial contamination: Unwanted presence of an undesirable biological element (bacteria, toxin, fungus, etc...) in a cosmetic product. The risk of contamination increases with the percentage of water in the formula. Indeed, bacteria and molds proliferate in an aqueous environment.
Minimum durability date (M.D.D.): Date until which a cosmetic must show no signs of degradation and must continue to fully perform its function. It must either be introduced by a pictogram in the shape of an hourglass, or by the formula: "Best used before the end of...", and is expressed in month/year or day/month/year. It is only mandatory for cosmetic products whose minimum durability is less than 30 months before opening. For those which can "live" longer, only the indication of the period after opening (P.A.O.) is required. Beyond this date, and even if the product has not been opened, it may lose quality, stability and effectiveness.
Mineral oil: Synthetic oily material obtained by distillation and refining of fossil fuels (coal, petroleum or certain shales). This liquid is composed mainly of saturated hydrocarbons. Among the most popular, we have kerosene, silicone and petroleum. In cosmetics, mineral oils are used to fight against dryness, skin dehydration and bring suppleness to the skin. Indeed, it deposits an occlusive film on the surface of the skin, which will limit its natural losses in water and keep it artificially hydrated.
Mucous membrane: Tissue lining made up of epithelial cells lining the internal wall of hollow organs, including the oral cavity, the respiratory system, the digestive tract, the vaginal canal, etc... The specificity of the mucous membrane is to be permanently humidified. It produces mucus (a viscous and translucent secretion) to prevent the tissues from drying out and to protect the organ that is covered with it from foreign particles.
Nail: A hard, numb, keratinized layer of skin that covers the tops of the fingertips and toes in primates and humans.
Nanomaterial: Insoluble or bio-persistent material, intentionally manufactured, containing free particles in aggregate form, at least 50% of which have one or more external dimensions on the nanometric scale (1 nanometer corresponds to one billionth of a meter). Nanomaterials are used in particular to increase the effectiveness of cosmetic products, by encapsulating the ingredients. They can also be used to optimize texture characteristics. The use of nanomaterials in cosmetics is highly regulated in Europe. Since July 11, 20213, the European Cosmetic Regulation n°1223/2009 establishes that the presence of nanomaterial must be mentioned on the list of ingredients of cosmetic products. In addition, the mention [nano] on the label of the cosmetic product must follow the name of the nano-ingredient. The nanomaterials authorized in cosmetics are carbon black as a colorant, as well as 4 ingredients used as UV filters: titanium dioxide, zinc oxide, tris-biphenyl triazine and methyl bis-benzotriazolyl tetramethylbutylphenol.
Natural hydration factor (N.H.F.): Mixture of intracellular water-soluble and hygroscopic substances. These are mainly amino acids resulting from the proteolysis of filaggrin, pyrrolidone carboxylic acid (P.C.A.), lactic acid, carbohydrates and mineral ions (chloride, sodium and potassium). It has the capacity to fix and retain water molecules in the intracorneocyte matrix, and thus participates in the maintenance of the hydration of the corneal layer.
Nourishing: Said of a substance that will bring lipids to the skin. A nourishing product will then participate in the restoration of the hydrolipidic film and thus of the cutaneous barrier.
Occlusive: Said of a substance that forms an impermeable film on the surface of the epidermis. Among the occlusive agents, one finds in particular kerosene, petroleum jelly, wheat germ oil, etc... The disadvantage is that these substances can block the pores and therefore contribute to the appearance of blackheads.
Oily Macerate: Result of an extraction technique (maceration) of a part of a plant by infusing it in a vegetable oil. The oil then becomes the carrier of the active principles contained in the plant.
Oxidation: Chemical reaction, often caused by oxygen, consisting of a transfer of electrons between reactants, as for example the oxidation of iron which leads to rust. The chemical species that captures electrons is called an "oxidant", while the one that gives them up is called a "reducer".
Papule: A dry, solid skin lesion (without liquid or purulent content when pierced), more or less raised, less than 5 mm in diameter, pink to red in color, sometimes painful and may affect any area of the body. Various factors can be the cause of the appearance of papules on the skin: it can be an allergic reaction, skin irritation, infectious diseases (chicken pox, eczema, etc...), insect bites or wart. However, it can evolve into a pustule.
Peeling: Method of aesthetic medicine consisting of applying a chemical substance to the skin, such as HA, salicylic acid or homogenized TCA, in order to provoke a limited and controlled desquamation of the cells of the epidermis, or even the superficial layers of the dermis. There are 3 types of peels depending on the type and concentration of acid used: superficial/soft, medium and deep peels. The purpose of this procedure is to regenerate the skin and thus improve the quality of the skin in terms of radiance, texture or homogeneity. It can treat and erase a large number of visible skin defects: dullness, hyperpigmentation, dilated pores, acne and oily skin, acne scars and signs of skin aging (wrinkles, fine lines, loss of tone).
Period After Opening (P.A.O.): Recommendation of the maximum time a product can be used once it has been opened. It is symbolized on the packaging of the cosmetic by a small pictogram in the form of a number followed by the letter M (for "month") embedded in an open jar. The products with a P.A.O. are those that can be kept closed for more than 30 months, unlike the D.L.U. After this period of time, the product may lose quality, texture, color or microbiological safety.
Persistent Pigment Darkening (P.P.D.): In vivo method of measuring the level of protection against UVA. It evaluates the pigmentary response, following the photo-oxidation of melanins, 2 hours after exposure to UVA. The UVA protection factor is calculated as the ratio between the doses of radiation required to produce pigmentation with and without sunscreen products. Sunscreen products should have a S.P.F./UVA index ratio of less than 3, ensuring effective and balanced UVA protection.
Phanera: Any apparent epidermal formation characterized by intense keratinization. In humans, the main phanera are hair, teeth, nails and hair.
Pheromone: Chemical compound or mixture of substances produced by the exocrine glands of most animals and some plants, influencing the physiology and behavior (sexual, aggression, maternal, etc.) of individuals of the same species.
Pilosebaceous/piliferous follicle: Small pocket where the hair will arise and which crosses the epidermis and the dermis. It is made up of a hair, its sheaths, sebaceous glands that produce sebum, a muscle (to straighten the hair), and in certain areas of the body (armpits, around the anus and nipples) apocrine sweat glands that secrete sweat and pheromones. Their role is to elaborate the hair and to intervene in the production of sebum which increases the impermeability of the corneal layer. The pilosebaceous follicles are distributed over the entire surface of the skin, except for the palms, soles, navel, nipples and the sides of the fingers and toes.
Photosensitizer: Refers to a chemical or drug substance that makes the skin ultra-sensitive to solar radiation, resulting in a skin rash. Not to be confused with photosensitive.
Photosensitive: Refers to a substance that is sensitive to the sun and is therefore susceptible to degradation and ineffectiveness if exposed to UV light. Not to be confused with photosensitizer.
Phototype: Scale for classifying skin types into 6 categories, based on the skin's reaction to the sun. Phototype I corresponds to the very light skin type and therefore the most sensitive to the sun. Phototype VI corresponds to the darkest phototype and therefore has a better tolerance to UV rays.
Photo-aging: Premature aging of the skin caused by overexposure to the sun's UV rays or to artificial sources. UVA rays are the main cause of photoaging of the skin. Compared to UVB, they penetrate deeper into the dermis and trigger the formation of free radicals. These free radicals then cause damage to the DNA and alter the skin cells, especially the collagen and elastin fibers. Just like the sun, blue light emitted by the sun or by computer or cell phone screens is also responsible for premature skin aging, but to a lesser extent than UVA. Indeed, by infiltrating the dermis, blue light progressively reduces the capacity of skin cells to regenerate.
Pigment: A chemical coloring substance, natural or synthetic, of mineral or organic origin, which gives organic materials their color.
Plant oil: Oil from oil plants, in other words a plant whose seeds, nuts or fruits contain lipids. It is obtained by cold mechanical pressure (i.e. the raw material is not heated so as not to denature it). This so-called virgin oil, which has not been refined after pressing, is rich in essential unsaturated fatty acids (omega-3, 6 and 9), fat-soluble vitamins (A, D, E and K) and trace elements. When applied externally to the skin, plant oils are known to nourish, soften, soothe irritations, repair the skin (burns, cracks, stretch marks), protect the skin from dehydration by creating a lipidic film on the surface of the epidermis and boost cell regeneration.
Pouch: Swelling under the eyes due to poor blood and/or lymphatic circulation and sometimes to an accumulation of fat associated with sagging skin.
Pore: A small hole in the surface of the skin from which sweat and sebum are released.
PH (Hydrogen potential): A parameter used to measure the acid-base state of a medium as a result of its hydrogen ion concentration. The pH scale ranges from 0 to 14. A solution with a pH below 7 is acidic, if the pH is equal to 7 the solution is neutral, and if the pH is higher than 7 the solution is said to be alkaline or basic. The skin has a naturally acidic pH, which allows it to protect itself from certain pathogenic bacteria: this pH is called physiological pH.
Preservative: Chemical compound used to inhibit the proliferation of micro-organisms (bacteria, mould) in cosmetic products and thus prevent their decomposition in order to guarantee the safety of the product. It is particularly added to cosmetic preparations containing water because, unlike oil, the presence of water favors the development of microorganisms. To be used in a cosmetic product in Europe, a preservative must be on the list contained in the European Cosmetic Regulation No. 1223/2009, such as parabens, phenoxyethanol, etc. ...
Propionibacterium acnes or Cutibacterium acnes: Anaerobic germs, lipophilic, commensal of the skin and the mucous membranes. This bacterium is an integral part of the cutaneous microbiome participating in its balance, where it colonizes the hair follicles and sebaceous glands. It feeds mainly on fatty acids contained in sebum. Normally harmless, this micro-organism is suspected of being involved in the development of acne. In fact, research has shown that acne is associated with the proliferation of P. acnes that secretes pro-inflammatory substances.
Protein: Macromolecule, composed of amino acids. This is the basis of all living organisms. Indeed, protein ensures a multitude of functions within the living cell and in the tissues: enzymatic, structural role, in the configuration of the DNA, the regulation of the gene expression, the energy metabolism or the transmission of cellular signals.
Protection factor (P.F.): Measure of the level of effectiveness of a sunscreen against sunburn induced by UVB. It is also called "Sun Protection Factor (SPF)". In other words, this index translates the ratio between the time necessary to trigger an erythema on an area of the skin protected by a sun protection product and on the same area of the skin not protected.
Pruritus or itching: A feeling of irritation on the skin or scalp resulting in an urge to scratch.
Psoriasis: A non-contagious, systemic, chronic inflammatory skin disease caused by immune dysfunction. It manifests itself by red patches covered with white dandruff corresponding to deposits of dead keratinocytes. The usual locations are the elbows, knees, lower back, forearms, but also the scalp and nails, and sometimes the hands and feet.
Purifying: Refers to a care product that thoroughly cleanses the skin of impurities and thus removes anything that could cause imperfections. In fact, this type of cosmetic helps to eliminate excess sebum, and to unclog and tighten pores.
Pustule: Dermatological inflammatory lesion, less than 5 mm in diameter, characterized by an epidermal relief in a well-delineated and circumscribed area containing a whitish or yellowish purulent fluid. It is related to the aggravation of an already existing papule. Indeed, the pustule is in the majority of the cases due to infections.
Relipidating: Refers to a care product that restores the correct level of lipids to the skin, thus restoring the skin's barrier function and improving skin hydration.
Rosacea: Chronic skin condition, localized on the center of the face (cheeks, nose, forehead, chin), which manifests itself by redness, a sensation of heat, couperose, tingling and pimples, following its evolution over time. It is linked to a hyperreactivity of the blood vessels which dilate in an excessive way.
Saponification: Total chemical reaction between a fatty substance (vegetable oil, animal fat, vegetable butter, etc.) and a strong base, necessary for the manufacture of a soap: either with soda (sodium hydroxide) for solid soaps, or with potash (potassium hydroxide) for pasty or liquid soap.
Scar: Result of the regeneration of the tissue following a lesion of the dermis.
Surgras soap: Mild product and less irritating than the classic soap, enriched with nutritive agents surgraissants like vegetable oils, vegetable butters, glycerin, etc..., thus allowing to clean the skin without drying it out. It thus makes it possible to protect, to hydrate and to help with the restoration of the hydrolipidic film of the skin.
Sebum: Oily secretion, whitish and thick, elaborated by the sebaceous glands of the skin, rich in fatty acids, playing an important role in the protection of the skin (fungistatic and bactericidal action). In addition, by mixing with sweat, sebum forms the hydrolipidic film that protects the epidermis from external aggression and drying out.
Serious adverse reaction (S.A.R.): Adverse reaction resulting in temporary or permanent functional incapacity, disability, hospitalization, congenital anomalies, immediate vital risk or death, according to the European Cosmetic Regulation n°1223/2009.
Scalp: Skin covering the skull. It acts as a physical barrier and thermal insulator. The scalp can sometimes be the home of skin diseases such as psoriasis or alopecia.
Skin: Flexible and resistant organ that is both the largest and the heaviest in the human body and that covers the entire body. It is made up of 3 layers: the epidermis, which is constantly renewed, the dermis and the hypodermis, which provides the fibrous structure. It has several fundamental roles, including a protective barrier against chemical and physical agents (sun, pollution, infections, shocks, etc.. ). It is reinforced by the action of keratin and melanin. It regulates heat by dilating blood vessels and evaporating sweat, and synthesizes vitamin D following exposure to UV rays.
Skin aging: Natural and unavoidable physiological process that induces structural damage to the skin and alterations in skin functions. Two mechanisms are responsible for the visible aging of the skin:
Intrinsic/chronic aging, which is time dependent and genetically linked to changes in the structure and function of the skin (decreased activity of the sebaceous and sweat glands, loss of elasticity of the dermis, slowing of cell renewal, decreased number of melanocytes and defects in wound healing). The causes of chronic aging are oxidative stress, telomere shortening and variations in hormonal activity.
Extrinsic aging is influenced by environmental factors that accelerate natural aging, such as UV exposure, smoking, unhealthy lifestyle, air pollution, alcohol abuse, etc...
Thus, skin aging results in the appearance of wrinkles, sagging skin, a change in the appearance of the complexion and the appearance of surface abnormalities (pigment spots, redness, dilated vessels, etc.)
Skin flora: A group of bacterial and fungal species that live permanently on the surface of the skin in symbiosis with the human body. Adult skin is home to more than 500 different species, the main ones being Staphylococcus, Corynebacterium, Propionibacterium, Candida albicans and Malassezia furfur. This cutaneous microbiota participates in the defense of the skin against pathogenic germs and also constitutes a protection against the inflammation of the epidermis. However, an imbalance of this flora can lead to a pathological situation, for example the development of cutaneous mycoses.
Skin sensitization: Immunological skin reaction following repeated local contact, in small doses, after a more or less long period of time with a substance known as sensitizing.
Skin barrier: Physical barrier function of the epidermis that plays a role in protecting the organism from the external environment. The cutaneous barrier includes all the mechanisms of defense of the skin: cutaneous flora, hydrolipidic film and corneal layer (the most superficial layer of the epidermis). This barrier prevents water loss and reduces the penetration of toxic substances or pathogenic germs.
Serum: Cosmetic care with a fluid, light and penetrating texture, full of active ingredients. It is designed to treat various skin problems and thus provide a targeted response to the needs of the epidermis.
Solvent: A liquid component with the property of dissolving, diluting, suspending or extracting other substances to form a solution.
Soothing: Refers to a substance that helps reduce discomfort on the skin and/or scalp.
Surfactant: Chemical compound that modifies the surface tension between two surfaces. Surfactants are amphiphilic molecules with a lipophilic part (attracted to lipids) and a hydrophilic part (attracted to water). This amphiphilic structure gives them the ability to aggregate at the surfaces between water and other substances that are not very soluble in water, such as oil. They are therefore able to solubilize two immiscible phases. Surfactants are generally used for their foaming, washing or emulsifying effect, and thus enter the formulation of cosmetic products such as shampoo, shower gel, soap, etc... There are 4 types of surface-active compounds, more or less respectful of the epidermis: cationic, anionic, amphoteric and non-ionic. Anionics and cationics are known to be the most irritating, while amphoterics and non-ionics are the best tolerated by the epidermis. Among the surfactants, we can mention caprylyl/capryl glucoside, sodium laureth sulfate, sodium lauryl sulfate, sodium cocoyl isethionate, etc...
Squame: Fine and small flakes of dead skin, looking like flakes, which spontaneously detach from the epidermis.
Sweat: Colorless and odorless biological liquid, mostly composed of water with added mineral salts and lactic acid. However, sweat is not the same everywhere and differs according to its origin. In fact, it can be produced by two distinct types of sweat glands: the eccrine sweat glands and the apocrine sweat glands.
Thickener: Ingredient used to reduce the liquid character by increasing the viscosity of formulas.
Toxicologist: Scientific expert in charge of studying the harmful effects of products on human health (drugs, cosmetics, solvents, etc.).
Transpiration or sweating: Active phenomenon characterized by the release of sweat, secreted by the sweat glands, through the pores of the skin to regulate skin temperature.
Ultraviolet (UV): Electromagnetic radiation invisible to the naked eye that emits in the wavelength range of 100 to 400 nanometers (nm). Depending on its wavelength, it can penetrate the ozone layer and have different effects on health. The shorter the wavelength, the more harmful it is, but the less easily it penetrates the skin.
Undesirable effect: A reaction that is harmful to human health, attributable to the normal or reasonably foreseeable use of a cosmetic product, according to the European Cosmetic Regulation n°1223/2009.
Unsaponifiable: Elements of a fatty substance that are not transformed into soap during a saponification reaction. These include sterols, hydrocarbons (squalene, etc...), fatty alcohols (waxes, etc...), fat-soluble pigments, vitamins, polyphenols, minerals, etc. .... This unsaponifiable fraction allows to preserve all the properties and virtues of the fatty substance. In general, it represents only 0,5 to 2% of the cosmetic product, but can reach 15% for the shea butter, 20% in beeswax and reach 50% for jojoba oil.
UVA: Radiation originating from electromagnetic energy emitted by the sun. UVA represents 95% of the UV rays that manage to cross the ozone layer. They have a wavelength of 315 to 400 nm. UVA penetrates the skin very deeply and can cause long-term damage such as hyperpigmentation, skin aging, photosensitization reactions and the development of skin cancers. UVA is present all year round, in all latitudes and is able to penetrate clouds and windows.
UVB: Radiation emitted by the sun where only 5% reach the surface of the Earth. They have a wavelength of 280 to 315 nm. UVB penetrates less deeply into the skin and is mainly responsible for long-term tanning but also for sunburns, allergic reactions and most skin cancers. UVB is able to penetrate clouds, but is stopped by glass.
UVC: Fraction of ultraviolet radiation emitted by the sun with a wavelength of 100 to 280 nm. UVC is completely absorbed by the ozone layer of the atmosphere and therefore does not reach the surface of the Earth. Their short wavelength makes them extremely energetic and dangerous for all forms of life. They are artificially created and used in hospitals and biological laboratories for their germicidal function.
Vegan: Term defining someone or something that does not use/consume any animal products, and therefore does not contain any animal products/ingredients.
Viscosity: The viscosity is high if a liquid is sticky and low if a liquid is very fluid.
Vitamin: An organic substance with no energy value but essential to the proper functioning of the body. However, the human body does not know how to manufacture them, with the exception of vitamin D and K, and they must therefore be provided by the diet. A vitamin deficiency can lead to serious disorders. They are essential because they are involved in many functions of our body (growth, transformation and use of macro-nutrients, synthesis of hormones, immune system, vision, synthesis of collagen, manufacture of DNA, etc. ...). To date, there are 13 vitamins: 9 water-soluble vitamins (vitamin B1, vitamin B2, vitamin B3, vitamin B5, vitamin B6, vitamin B8, vitamin B9, vitamin B12, vitamin C) and 4 fat-soluble vitamins (vitamin A, vitamin D, vitamin E and vitamin K).
Waterproof: The ability to resist water.
Wrinkle: A fold that has formed on the surface of the epidermis, due to a progressive loss of firmness and elasticity of the skin related to aging. There is a difference between fine lines and wrinkles. Indeed, lines 0.2 to 1 mm deep are considered as fine lines, but when their depth exceeds 1 mm, they are considered as wrinkles.
Xerosis: State of dryness of the skin. It appears when the water content is much lower than normal. It can have different causes such as certain pathologies (eczema), deficiencies (especially in vitamin A) or external factors (contact with irritating substances or treatment with certain medications).