Cosmetics are used extensively on skin and hair to keep them clean and healthy. Regularly, an average human uses a minimum of 2 to 3 kinds of cosmetics products.
This is important to understand because the safety of cosmetic or makeup products is one of the most important things for any manufacturer of cosmetic products. There should be an ethical usage of drug policy and proper regulation on the raw materials used.
What is the basic concept of cosmetic safety?
There are several ingredients used in cosmetics these days, and most of them are documented for their safety features and how to use them properly.
But as technology is growing, there are new ingredients introduced in the market with different claims altogether. Also, these new ingredients are not listed in a reference book. These have been created because of clinical testing of several raw materials and might be used by specific organizations.
Here, we will have to understand the meaning of Reasonably Estimated As Safe (REAS);
Substances reasonably estimated as safe were accepted for ingredients that have been used for a long time, similar to generally recognized as safe (GRAS).
GRAS; Substances generally recognized by experts as safe, for food additives.
However, concerns about safety or health problems are changing with time. Therefore, it has become even more necessary to reconsider the scientific evaluation of cosmetic ingredients as reported in Cosmetic Ingredient Review (CIR) established in 1976.
The need for safety testing is based on the concept that cosmetics are beneficial to human skin only if their safety is confirmed in proper usage. Therefore, the basic strategy for the safety assessment of cosmetics is the same as for medical drugs or other chemical substances.
What are different safety evaluation methods in cosmetics?
As we have already understood the concept behind testing the safety of cosmetic products, now we will try and understand how cosmetic products are tested for different evaluation parameters;
1. Skin Irritation: While checking the safety of cosmetic products, it is important to check if the raw materials used in cosmetics are irritative to the skin or not.
There should not be any rash when applied to the skin. The cause of contact dermatitis (rash) is not always due to cosmetic ingredients. Even if the safety of cosmetics is verified, it is known that environmental conditions such as temperature and humidity when the cosmetic is used, misuse by the consumer, and the user's constitution and physical condition may all cause contact dermatitis.
Skin irritation is caused by the direct toxicity of chemicals on cells or blood vessels in the skin and is different from contact allergy caused by the immune response described later. This type of response is observed in many people when exposed to strong acids or alkalis.
Animals like Rabbits and Guinea Pigs have long been used for testing due to their similar response to that of humans and their high responsiveness.
The Draize Primary Skin Irritation Test is often conducted on rabbits.
Guinea pigs are also used for skin irritation tests since they are easily handled. In the case of guinea pigs, the back or the flank is clipped free of hair, and the test material is applied once or repeatedly to the skin without a patch test plaster.
2. Sensitization (allergenicity): Allergy can occur when the body is continuously is exposed to the chemicals with sensitizing potential. If the chemicals are administered through the skin, it is called contact sensitization.
Sensitization response is different from irritation, which is localized, but sensitization might have a full-blown effect on the body.
Contact Sensitization is also classified as a delayed-type hypersensitivity because the inflammatory reaction is often delayed. It is an important test for the evaluation of the safety of cosmetics products.
Process of Sensitization Evaluation:
Although the maximization test has high sensitivity, it is occasionally criticized because it is sometimes not easy to emulsify the test material with FCA, especially final products, and intradermal injection may not represent the risk of real use.
In this case, the adjuvant and patch test method is used, which retains high sensitivity.
There are some non-FCA methods, such as Buehler's method, and the open epicutaneous test, which are also popular.
3. Phototoxicity: Some chemicals may cause a skin irritation response only in the presence of light, and hence they are termed phototoxic ingredients.
For Example, Bergapten (5-methoxy psoralen) is found in bergamot oil, a fragrance material, which causes Berlock dermatitis.
In screening these types of materials, it is best to use sunlight as the light source, but in actuality, sunlight varies greatly in energy and wavelength distributions depending on the season and time of day.
Consequently, phototoxicity testing often uses a xenon arc lamp or a commercial black lamp. Since the wavelength band causing the inflammation response varies with the material, it is important to select the appropriate light source. Generally, materials that have an absorption band in the UV region are tested. Therefore, long-wavelength UV light (UVA) or mid-wavelength UV light (UVB) at a non-erythema dose rate is generally used.
Both guinea pigs and rabbits are used as test animals. The test material is applied to the clipped back skin of the animal and the phototoxicity is evaluated as the difference between the response of the part with light exposure and that without light exposure.
4. Photosensitization (photoallergenicity): Photosensitization is an allergic response observed only in the presence of light. Photoallergencity has been reported for several types of materials including UV absorbents, bactericides, and fragrances. It is most important to verify that neither cosmetic products nor their ingredients are photoallergic since cosmetic products on the skin are commonly exposed to sunlight in daily life. In particular, it is essential to evaluate the photoallergenicity of sunscreen products and UV absorbents which are usually used in the presence of strong UV light.
Although the response mechanism of photosensitization is not clearly understood, it is believed that the process involves;
Mice and Guinea pigs are often used as test animals.
5. Eye Irritation: Cosmetics, especially those used on the face and around the eyes such as eye-shadows or mascaras, and hair-care products like shampoos, etc, may enter the eyes during use.
Consequently, it is essential to confirm their safety concerning eye irritation potential. The Drazie method has long been used for this purpose.
The test material is applied on one eye of a test rabbit and the response of cornea, iris, and conjunctiva is observed over a certain time.
6. Toxicity:
7. Mutagenicity: This type of testing is used to investigate materials-inducing mutations. Such materials may conceivably affect the incidence of inheritable diseases in man. It has been confirmed that many materials that cause cancer have mutagenic activity and many of the mutagenicity tests investigate materials for both mutagenic and carcinogenic activity.
8. Reproductive toxicity: This type of testing is used to evaluate whether or not the chemicals have toxic effects on reproduction, for example on the in utero fetus, to examine the dangers of the test material to the reproductive process. In animal experiments, the period from preconception to the end of lactation is divided into three parts, and the test is carried out for each period. Test materials are administered,
In most cases, rodents and rabbits are used as test animals. However, cosmetic materials are not commonly subjected to this test.
9. Absorption, distribution, metabolism, excretion: Cosmetics and their ingredients are defined as materials that have only a mild action on the human body. Nevertheless, it is important to know the possible effect of cosmetic ingredients on the body after percutaneous absorption to understand the mechanism of irritation or toxicity as well as to obtain information regarding evaluation and prediction of the safety of ingredients.
The distribution in each organ of the body is examined using radiolabeled compounds on test animals. Also, the concentrations in the blood and urine are measured, and the metabolites are analyzed. To test the percutaneous absorption by a simple method, a small sheet of skin excised from a test animal mounted on a diffusion cell is generally used.
10. Testing on humans (patch test, usage test): This is again important, as it doesn't matter how much you complete testing on animals, there are some basic differences, which may cause differences in the results when testing is done on humans.
What are various Animal Test Alternatives?
A variety of animals and test methods are used in testing the safety of cosmetics for humans but in recent years such testing has become the focus of some criticism. Therefore, there have been several efforts to get some alternatives to animal testing.
Sometimes, there is shortening the test time on animals and sometimes there has been some refinement in the testing process itself.
Several countries have started making efforts to develop alternatives to animal testing. The Foundation for the Replacement of Animals in Medical Experiments (FRAME) was established in the UK in 1973.
At present, validation, which is carried out to confirm whether previously reported in-vitro testing methods can be applied to practical use, is gaining ground.