Content

Introduction

Among cosmetic products, hair dyes are nowadays used by more than 60% of women and by percentages between 5 and 10% of the male population with a clear tendency to increase. The average frequency of use is at least 6 -8 times a year. And not just to cover gray hair: these products, in fact, help you feel younger and more attractive, contributing to the psychological well-being of the individual. More and more frequently, especially in young people, in fact, it is possible to observe multicolored heads with colors that only a few years ago would have seemed impossible.

The habit of dyeing one's hair has ancient roots: the discovery in the pyramids of a powder obtained from the leaves of lawsonia inermis, known as henna, and the discovery of red hair in some mummies testify that the women of ancient Egypt already used them; in Greece the dyes were the same used for fabrics while in ancient Rome natural ingredients were mixed, including chamomile and lupine flowers, egg yolks, cypress leaves, with other dyes, such as black antimony and lead, without think about possible negative health effects.

Europe is a world leader for the cosmetics industry and also the largest exporter: the hair dyes market in the European Union represents about 8% of the total value of production by the cosmetic industries. European Commission has implemented a comprehensive strategy for the safety of hair dyes in Europe.

Like other cosmetic products, hair dyes are regulated by specific European legislation (Regulation (EC) No. 1223/2009) which, which entered into force in Italy in July 2013, has among its main purposes that of guarantee the protection of health and consumer information; it also provides for the evaluation of the safety of products when they are applied under normal conditions of use, imposing a total ban on experiments on animals to demonstrate it.
The manufacturing companies, for each ingredient they intend to use, must prepare technical dossiers, to be submitted to the evaluation of a European committee of experts (Scientific Committee for Consumer Safety - SCCS), which demonstrate the safety of the substances before the finished product is marketed.

Hair dyes are among the substances most frequently analyzed by the SCCS. The coloring substances that cannot be used without causing damage to the health of the consumer, or whose use cannot exceed a specific quantity, are present in two lists, known as Annex II and III of the Regulation, which are continuously updated.
The Regulation also prohibits the use of substances classified as carcinogenic, capable of inducing mutations in genes (mutagenic) or toxic for reproduction (also indicated with the initials CMR), except in exceptional cases in which it is possible to identify a level ( threshold) below which no harmful effects on health occur.

The hair and the different dyes

Hair is made up of proteins with a structural function (keratin), dye (melanin) and water, lipids, pigments and trace elements. They grow on average at a rate of about 0.3 millimeters (mm) per day; this value, however, can change a lot from person to person.
The hair has a variable growth cycle between 2 and 6 years after which it falls out and is replaced by another hair.

There are three main types of tinctures:

  • temporary
  • semi-permanent
  • permanent

The temporary dyes and the semi-permanent are progressively released (in common parlance it is said that disassemble ) with hair washing: one or two washes for temporary dyes, 6 to 10 for semi-permanent ones.

The temporary colorings they cover only the outer surface of the hair without penetrating its structure. They are generally used to change the color tone or give a new shade to the natural hair color without changing it. For this reason, they are often also called reflective. Generally, they are ready-to-use products (it is not necessary to mix them with other products before use) in the form of shampoos, masks or mousse.

The semi-permanent dyes as well as the external surface they are able to reach the superficial layers of the hair (cortex). Like temporary dyes, they do not allow you to change color but allow a limited coverage of gray hair over time.

The permanent dyes they are also called oxidative: they penetrate deeply and alter the natural pigment of the hair (melanin). They are used to cover gray hair or change the color in a radical way. Oxidation is a chemical process which almost always consists in the combination of a substance with oxygen.It is one of the most common reactions even in living beings and generally produces energy (also in the form of heat): it is in fact an oxidation the reaction that through breathing allows the oxygen of the atmosphere to be transformed into energy for the cells and is always a oxidation the reaction that causes some foods to change color such as meat, potatoes (read the Buffalo), bananas or artichokes exposed to air (and therefore to oxygen).

Hair dyes consist of products that must be mixed immediately before use: one, said alkaline agent, makes the outer layer of the hair permeable, thus making the substances with an oxidizing and bleaching action penetrate deeply (which lighten the melanin pigments, for example hydrogen peroxide that decolourates and releases oxygen) and the coloring agent generally consisting of a substance colorless which only after oxidation transforms into a real permanent light-stable dye. The effect is long lasting and cannot be removed with washing. The choice of the concentration of hydrogen peroxide depends on the type of coloring: at low concentration (10-20% v / v) when you want to cover gray hair, or at a higher concentration (30-40% v / v) when you want to lighten color.

Dark hair dyes (such as black tones) use higher concentrations of dye than lighter tones and therefore exposure to these substances can be greater.

New generation dyes more and more often (about 70-80% of the European market) do not contain ammonia as an alkaline agent.

Effects on Health

The same considerations valid for all other cosmetic products apply to the dyes contained in hair dyes: the scalp on which they are applied must be free from severe irritation or cuts (Video).It is however possible that in some predisposed people, even if all the precautions indicated on the label have been followed, contact dermatitis of allergic origin may appear after the use of hair dyes.

Tinctures produced before 1980 contained some known or suspected carcinogenic agents; it was therefore hypothesized, on the basis of animal studies, that they entail a greater risk of developing tumors, especially of the blood (leukemia and lymphomas) and of the bladder. Over time these ingredients with suspected carcinogenic action have been replaced with more dyes safe. Furthermore, some epidemiological studies suggested that hairdressers and barbers (using these substances daily for work, as opposed to the consumer in whom exposure is sporadic), could have a higher incidence of bladder tumors. However, these data have not been confirmed: an equally large number of studies, especially those conducted in Europe, have given negative results and recent analyzes of all available data (meta-analyzes) have indicated the absence of correlation between the use of dyes and There is a study released in 2020 (in which about 117,000 women were followed for about 30 years) whose results indicated that personal use of hair dyes is not associated with an increased risk of cancer or mortality. authors found some positive correlations, which they themselves associate with specific characteristics of the women under examination and consider as data to be confirmed. It should be noted that the study was conducted by Austrian researchers but with women residing in the USA, where the regulations on chemical components and the safety of the dyes are less restrictive than in Europe. At the moment, therefore, there is no scientific data to support the news published on the internet on the relationship between hair dyes and cancer.Even the IARC (International Agency for Research on Cancer) has not classified personal use of hair dyes as a carcinogen.

If, following the use of hair dyes, undesirable effects occur such as, for example, dermatitis, it is a good idea that the person himself, or professional users (hairdressers or barbers), report them directly to the Ministry of Health. If the citizen is directly responsible for the report, it is advisable to attach a medical certificate showing the disturbance. The availability of these reports can, in fact, be of great help for a better control and evaluation of cosmetic products on the market.

Prevention and control

Since 2003, the European Commission has paid close attention to the safety of hair dyes. Since then, following the assessments carried out by the Scientific Committee for Consumer Safety (SCCS), about 180 ingredients have been banned from the market both because they were assessed as unsafe based on the available data, and due to the lack of sufficient data to carry out the assessment. These substances are listed as unauthorized ingredients (or subject to specific limitations and restrictions) in the specific annexes of the European regulation for the safety of cosmetics. There are about 100 ingredients that have been considered safe and compliant with the requirements of consumer safety legislation. The Regulation also requires producers to indicate specific warnings on the label if the product contains substances that can cause allergies and sensitization. cutaneous, so that the consumer is informed (Video).

The safety assessment carried out in Europe, therefore, is particularly stringent, but this is not the case for other producing countries.This is why it is good to check the origin of the products you use and also ask your trusted hairdresser which products you use.

Therefore, there seems to be no reason to eliminate the use of tinctures on an individual level, even if a possible reduction in frequency can only be healthy. As for patients undergoing chemotherapy and in the following six months, the tendency is to advise against its use for fear of dermatological effects (allergies, hair loss problems).

If you use products at home for a do-it-yourself coloring, with permanent dyes it is necessary to strictly follow the instructions on laying times and pay particular attention to the alkaline agent when mixing, protecting your hands with plastic gloves. It should also not be forgotten that allergic reactions are often characterized by specific responses of each individual, so it is advisable to test (test) the product in small quantities on an arm before applying it to the scalp. hair before applying the dye so as not to remove the protective film of grease from the scalp and hair.

Supervisory activities

The Ministry of Health, which collects and verifies any reports of undesirable effects, is in charge of the supervision of cosmetic products on the market (cosmetovigilance), including hair dyes. The surveillance activities carried out on the territory by the Ministry of Health and the Regions concern controls to counter the sale and distribution of irregular cosmetic products (for example, ingredients present in greater quantities than permitted or non-regulatory labels or packaging) or entirely counterfeit.The fight against counterfeiting is particularly important because these are products manufactured illegally, and of unknown origin, which may contain prohibited and potentially dangerous ingredients for health and, therefore, the safety of which is not guaranteed.

Bibliography

Regulation (EC) n. 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products. (Official Journal of the European Union of 22 December 2009)

Ministry of Health. Cosmetics

Competition and Market Authority (AGCM). Legislative Decree 206 of 6 September 2005. Consumer Code

I tested E. The rainbow on your head. How safe is it to dye your hair? Newsletter of the "Istituto Superiore di Sanità". 2017; 30: 16-19

Italian Association for Cancer Research (AIRC). Are hair dyes cancerous?

In-depth link

European Commission. Scientific Committee on Consumer Safety (SCCS)

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