Tolerance of a cosmetic product: how is it evaluated?

It is essential that a cosmetic product poses no risk to the consumer under normal usage conditions or under unusual but foreseeable usage conditions. Safety tests exist to ensure this and are carried out by experts (doctor, toxicologist or holder of one of the degrees set by regulation).

It is important to understand that the ANSM (National Agency for the Safety of Medicines and Health Products) can order the withdrawal of any product from the market at any time if it is deemed dangerous to human health.

Here are several safety tests typically conducted before a cosmetic product is launched on the market. As a reminder, the conduct of animal testing within the territory of the European Union is prohibited for cosmetic products since September 2004 and for cosmetic ingredients since March 2009.

• The Skin Irritation Test or Patch Test

  Before a skincare product is launched on the market, at the stage of the finished product, patch tests on human volunteers are carried out. These involve a single application of the cosmetic product, for 24 or 48 hours on several volunteers, under occlusive or semi-occlusive patches on the arm or back. The presence of any potential skin reactions upon removal of the patch is then assessed (under medical or dermatological supervision).

• The Eye Irritation Test

  As the name suggests, this involves the study of ocular tolerance, which typically employs in vitro techniques (alternative methods to animal experimentation) such as HET-CAM (Hen's Egg Test - Chorioallantoic Membrane). The ocular tolerance test is performed on formulas intended for application around the eye contour and/or eyelashes. It is also recommended for treatments that may potentially come into contact with the eyes. Facial cleansers, shampoos, or face masks are among the various cosmetic treatments that are relevant to this study.

• The "use test"

  This pertains to the study of tolerance to repeated applications under normal conditions of cosmetic product use (2 to 3 weeks, 10 to 20 volunteers, sometimes tested in the crook of the elbow).

• The Sensitisation Test

  These sensitivity tests are known as HRIPT (Human Repeat Insult Patch Test) or RIPT (Repeat Insult Patch Test). They are typically conducted on a panel of 50, 100 or 200 volunteers who repeatedly apply patches containing the product in question to the skin on their back over a period of 6 weeks. If any reactions occur, they are observed, recorded and interpreted by a dermatologist to confirm or deny the allergenic nature of the product. These tests also determine whether or not the term "hypoallergenic" can be used on a skincare product.

• The Phototoxicity Test

  This test involves treating cells in vitro with the cosmetic product, then comparing the responses obtained after exposure or non-exposure to UVA light.

The results from these various tests must be included in the file related to each cosmetic product that accompanies its market launch. This file is called the DIP for Product Information File and includes a section titled "Report on the Safety of the Cosmetic Product".

To ensure the durability and protection of the skincare product over time, the formula must undergo a challenge test coupled with a stability test.

1. The challenge test involves the assessment of the performance of the preservative agent or agents contained in the skincare product. A certain concentration of germs is injected into the formula. The estimation is based on their rate of decrease over a defined period, in order to evaluate the effectiveness of the preservative system present in the cosmetic formula.

2. The stability test focuses on thestudy of the product's durability over time. The formula is subjected to accelerated ageing and an evaluation of its condition during storage or after transport. It is kept in an incubator at a specific temperature (usually 40°C) for several months. Subsequently, samples are taken to monitor various parameters: the development or absence of bacteria, changes in pH, viscosity, odour, colour etc.