Method of prognosis or diagnosis of acne-prone skin

Abstract

Method for prognosis or diagnosis of acne-prone skin The present invention relates to a method for prognosis or diagnosis of acne-prone skin, in particular linked to pollution. The present invention relates to a method, in particular in vitro, for prognosis or diagnosis of acne-prone skin of a subject, preferably linked to chronic exposure to pollution, comprising a step (a) of determining, in a sample of one or more hairs of said subject, the level of at least one marker chosen from the group consisting of polycyclic aromatic hydrocarbons.

Description

Title of the invention: Method for prognosis or diagnosis of acne-prone skin

[0001] The present invention relates to a method of prognosis or diagnosis of acne-prone skin, in particular linked to pollution.

[0002] Certain urban environments are regularly subject to pollution peaks. The individual in his daily environment and particularly in urban areas, can be subjected to multiple attacks on keratinous materials, and in particular the skin, by different air pollutants.

[0003] Among the known pollutants, we will first mention exhaust gases which have become a major issue in large cities, heavy metals but also fine particles which contain molecules such as polycyclic aromatic hydrocarbons such as benzo-a-pyrene or benzoanthracene.

[0004] These pollutants will in particular cause the deposition of particles on the surface of the epidermis in the skin, and among other consequences, induce premature aging of the skin marked by the presence of wrinkles and / or fine lines, extensive macules, lentigo simplex, redness, and / or a dull and / or uneven appearance of the complexion.

[0005] The present inventors have shown that prolonged systemic exposure to atmospheric pollution, in particular to certain pollutants such as PAHs, demonstrated by the detection of these pollutants in hair samples from the subjects studied, is associated with the development of acne-prone skin.

[0006] Identifying exposure to pollution as a factor responsible for the development of acne-prone skin could make it possible to prevent and / or treat them more effectively by specifically targeting these pollutants.

[0007] There is therefore a significant need for a new method of prognosis or diagnosis of acne-prone skin, particularly linked to pollution.

[0008] The present invention meets this need.

[0009] The present invention results from the unexpected discovery by the inventors that the detection of high levels of pollutants and in particular of certain PAHs, in subjects exposed to chronic systemic pollution, highlighted by the detection of these pollutants in hair samples from the subjects studied, is correlated with the development of acne-prone skin.

[0010] The present invention thus relates to a method, in particular in vitro, for prognosis or diagnosis of acne-prone skin in a subject, preferably linked to chronic exposure to pollution, comprising a step (a) of determination, in a sample of one or more hair(s) of said subject, of the level of at least one marker chosen from the group consisting of polycyclic aromatic hydrocarbons. Detailed description

[0011] Prognostic / diagnostic method

[0012] The subject of the present invention is a method, in particular in vitro, for prognosis or diagnosis of acne-prone skin in a subject, preferably linked to chronic exposure to pollution, comprising a step (a) of determining, in a sample of one or more hairs, the level of at least one marker chosen from the group consisting of polycyclic aromatic hydrocarbons.

[0013] By “in vitro method for diagnosing acne-prone skin” is meant here a method for determining whether a subject has acne-prone skin.

[0014] By "in vitro method for prognosis of acne-prone skin" is meant here a method for determining whether a subject is at risk of developing acne-prone skin.

[0015] By "developing acne-prone skin" or "developing acne-prone skin" is meant the appearance or occurrence of acne-prone skin.

[0016] By "pollution" is meant here exposure to particulate matter, in particular polycyclic aromatic hydrocarbons (PAHs).

[0017] Chronic exposure to pollution is advantageously chronic exposure to systemic type pollution.

[0018] By “PAH” or “polycyclic aromatic hydrocarbons” we mean both the parent PAHs and their metabolites.

[0019] By “subject” is meant here a human being, preferably aged between 25 and 45 years.

[0020] Preferably, the subject is a woman.

[0021] Preferably, the subject is of Asian type.

[0022] By "sample of one or more hairs" is meant one hair or one or more lock(s) of hair taken non-invasively, from said subject having in particular a length of approximately 12 cm from the root of the hair(s).

[0023] Preferably, the pollution is PAH pollution.

[0024] As is well known to those skilled in the art, PAHs are a subfamily of aromatic hydrocarbons whose structure comprises at least 2 condensed aromatic rings. They are produced by the incomplete combustion of organic matter (coal, oil, gas, waste and biomass) and released as environmental contaminants.

[0025] PAHs typically include acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo-b-fluoranthene, benzo-k-fluoranthene, benzo[a]pyrene, indcno| 1,2,3-« / pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, preferably acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene. These PAHs are especially called parent PAHs.

[0026] In addition, PAHs typically include 1-hydroxy-naphthalene, 2-hydroxy-naphthalene, 9-hydroxy-flurorene, 3-hydroxy-flurorene, 2-hydroxy-flurorene, 4-hydroxy-phenanthrene, 9-hydroxy-phenanthrene, 1-hydroxy-anthracene, 3-hydroxy-phenanthrene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 3-hydroxy-fluroanthene, 1-hydroxy-pyrene, 2-hydroxy-benzo[c]phenanthrene, 1-hydroxy-benz[a]anthracene, 4-hydroxy-chrysene, 6-hydroxy-chrysene, 11-hydroxy-benz[a]anthracene, 2-hydroxy-benz[a]anthracene, 3-hydroxy-benzo[c]phenanthrene, 8-hydroxy-benz[a]anthracene, 5-hydroxy-benz[a]anthracene, 3-hydroxy-chrysene, 1-hydroxy-chrysene, 4-hydroxy-benz[a]anthracene, 3,9-hydroxy-benz[a]anthracene, 2-hydroxy-chrysene, 8-hydroxy-benzo-b-fluoranthene, 1,7-hydroxy-benzo-b-fluoranthene, 12-hydroxy-benzo-b-fluoranthene, 8-hydroxy-benzo-k-fluoranthene, 9-hydroxy-benzo-k-fluoranthene, 7-hydroxy-benzo[a]pyrene,9-hydroxy-benzo[a]pyrene, 6-hydroxy-indeno[l,2,3-cd]pyrene, 1-hydroxy-indeno[l,2,3-cd]pyrene, 8-hydroxy-indeno[l,2,3-cd]pyrene, preferably 1-hydroxy-naphthalene, 2-hydroxy-naphthalene, 9-hydroxy-fluorene, 3-hydroxy-fluorene, 2-hydroxy-fluorene, 4-hydroxy-phenanthrene, 9-hydroxy-phenanthrene, 3-hydroxy-phenanthrene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 3-hydroxy-fluoranthene, 1-hydroxy-pyrene, 3-hydroxy-chrysene, 3,9-hydroxy-benz[a]anthracene, 2-hydroxy-chrysene. These PAHs are especially called PAH metabolites.

[0027] In a preferred embodiment, the PAHs are selected from acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene and benzo[a]pyrene.

[0028] By "chronic exposure" is meant here regular exposure, in particular daily, for a given period, preferably a period of more than one year, in particular a period of twelve months (typically corresponding to a growth of 12 cm of hair), possibly interrupted on one or more occasions for short periods, typically periods of less than one month, preferably less than one week.

[0029] The prognostic or diagnostic method according to the invention comprises a step (a) of determining, in a sample of one or more hair(s) of said subject, in par in particular a sample of a hair or lock(s) of hair of said subject, of the level of at least one marker chosen from the group consisting of polycyclic aromatic hydrocarbons.

[0030] Preferably, the level of said at least one marker in the sample is the mass concentration of said at least one marker in the sample.

[0031] The level of said at least one marker can be determined by any suitable technique.

[0032] The level of said at least one marker is determined using any analytical method suitable for the characterization or quantification of said polycyclic aromatic hydrocarbons, for example high performance liquid chromatography (HPLC), liquid chromatography coupled with mass spectrometry (LC-MS), gas chromatography coupled with mass spectrometry (GC-MS).

[0033] Preferably, the level of said at least one marker is measured by gas chromatography coupled with mass spectrometry (GC-MS), in particular according to the methods described in Appenzeller BMR, Mathon C, Schummer C, Alkerwi A, and Lair ML. Simultaneous determination of nicotine and PAH metabolites in human hair specimen: a potential methodology to assess tobacco smoke contribution in PAH exposure. Toxicol Lett. 2012;210(2):211-9 or Grova N, Salquebre G, and Appenzeller BMR. Gas chromatography-tandem mass spectrometry analysis of 52 monohy-droxylated metabolites of polycyclic aromatic hydrocarbons in hairs of rats after controlled exposure. Anal Bioanal Chem. 2013;Sep 7:PMID: 24013637.

[0034] In a particular embodiment, the diagnostic method according to the invention further comprises the steps consisting of: (b) comparing the level of said at least one marker measured in step (a) with a control, and (c) based on the comparison in step (b), determining whether the subject, in particular the subject's skin, has or is likely to develop acne-prone skin.

[0035] Preferably, the control is a reference value.

[0036] Even more preferably, the reference value is determined by the average value of the level of said marker in a given population, for example a population in a given age group, and / or having a defined skin type.

[0037] Even better, the reference value is the average value of the level of said marker in a population of subjects, in particular subjects as defined below, living in a low-polluted city, in particular a city having an air quality index of less than 100 for less than 100 days, in particular less than 85 days, over a year.

[0038] In a particular embodiment, said at least one marker is chosen from the group consisting of polycyclic aromatic hydrocarbons, preferably: a. selected from group a) consisting of acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo-b-fluoranthene, benzo-k-fluoranthene, benzo[a]pyrene, indeno[ 1,2,3-« / ]pyrcnc, dibenz-ah-anthracene, benzo-ghi-perylene, preferably acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo-b-fluoranthene, benzo-k-fluoranthene, benzo[a]pyrene, indeno[ 1,2,3-[( / ]pyrene, dibenz-ah-anthracene, benzo-ghi-perylene; and / or b. selected from group b) consisting of 1-hydroxy-naphthalene, 2-hydroxy-naphthalene, 9-hydroxy-flurorene, 3-hydroxy-flurorene, 2-hydroxy-flurorene, 4-hydroxy-phenanthrene, 9-hydroxy-phenanthrene, 1-hydroxy-anthracene, 3-hydroxy-phenanthrene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 3-hydroxy-fluroanthene, 1-hydroxy-pyrene, 2-hydroxy-benzo[c]phenanthrene, 1-hydroxy-benz[a]anthracene, 4-hydroxy-chrysene, 6-hydroxy-chrysene, 11-hydroxy-benz[a]anthracene, 2-hydroxy-benz[a]anthracene, 3-hydroxy-benzo[c]phenanthrene, 8-hydroxy-benz[a]anthracene, 5-hydroxy-benz[a]anthracene, 3-hydroxy-chrysene, 1-hydroxy-chrysene, 4-hydroxy-benz[a]anthracene, 3,9-hydroxy-benz[a]anthracene, 2-hydroxy-chrysene, 8-hydroxy-benzo-b-fluoranthene, 1,7-hydroxy-benzo-b-fluoranthene, 12-hydroxy-benzo-b-fluoranthene, 8-hydroxy-benzo-k-fluoranthene, 9-hydroxy-benzo-k-fluoranthene, 7-hydroxy-benzo[a]pyrene,9-hydroxy-benzo[a]pyrene, 6-hydroxy-indeno[l,2,3-c( / ]pyrene, l-hydroxy-indeno[l,2,3-c( / ]pyrene, 8-hydroxy-indeno[l,2,3-c( / ]pyrene, preferably 1-hydroxy-naphthalene, 2-hydroxy-naphthalene, 9-hydroxy-flurorene, 3-hydroxy-flurorene, 2-hydroxy-flurorene, 4-hydroxy-phenanthrene, 9-hydroxy-phenanthrene, 3-hydroxy-phenanthrene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 3-hydroxy-fluroanthene, 1-hydroxy-pyrene, 3-hydroxy-chrysene, 3,9-hydroxy-benz[a]anthracene, 2-hydroxy-chrysene; , and the subject is diagnosed as having acne-prone skin or likely to develop acne-prone skin if the level of said at least one marker measured in step (a), in particular the mass concentration of said at least one marker, is higher, in particular significantly higher, than a control, the control level being ty determining the level of said marker, in particular the mass concentration of said marker, in a sample of one or more hairs of a subject living in a low-polluted city, in particular a city with an air quality index of less than 100 for less than 100 days, in particular less than 85 days, over a year, the level of the markers typically being determined by gas chromatography coupled with mass spectrometry (GC-MS) typically as described above.

[0039] By "significantly higher" for the purposes of the invention, we mean a statistically significant increase in the level of the marker compared to the control level.

[0040] According to a preferred embodiment, the prognostic or diagnostic method according to the invention comprises a step of taking a sample of one or more hairs of the subject, in particular a length of about 12 cm from the root of the hair or hairs of the subject. This step is performed in a non-invasive manner, and in particular does not require local anesthesia. According to a preferred embodiment, the step of taking the sample is typically performed by cutting one or more hairs at the root of the hair or hairs, typically using scissors.

[0041] As detailed above, chronic exposure to pollution is correlated with the presence or development of acne-prone skin.

[0042] Also, the present invention relates to a method for preventing and / or treating acne-prone skin, preferably induced by chronic exposure to pollution, in a subject, said method comprising the following steps: (a) prognosing or diagnosing the subject as being likely to develop acne-prone skin or as having acne-prone skin, by implementing the prognosis or diagnosis method according to the invention, (b) if the subject is predicted or diagnosed as likely to develop acne-prone skin or as having acne-prone skin, treating said subject with a cosmetic composition comprising at least one active agent for the prevention and / or treatment of acne-prone skin, or at least one anti-pollution active agent, or mixtures thereof. Acne-prone skin Acne vulgaris is a multifactorial disease (face, scapular region, arms and intertriginous regions). It is the main cause of the most common dermatoses. It is important not to trivialize this disease and to treat it correctly, because it can have disabling psychosocial consequences, particularly due to the formation of scars.

[0044] In the mildest form, it affects almost every human being. Its frequency is highest at the age of puberty, but it can manifest itself for the first time from the age of 7 to 9 years and up to ages exceeding 40 years. It is common to suffer acne even after the age of 25. Acne also affects both men and women. Acne is a disease of the sebaceous gland follicle. The following pathogenic factors play a determining role in the formation of acne: - genetic predisposition, - androgen, - abnormally increased keratinization (keratinization disorder) in the infundibular portion of the hair follicle. In fact, in the deepest parts of the infundibulum, a higher than normal quantity of keratinocytes is formed. These cells differentiate into horny cells that gradually obstruct the lumen of the follicular canal. The physiological process of continuous desquamation of the acroinfundibulum towards the surface is disrupted by the increased adhesion of the horny cells produced. A hyperkeratotic plug forms, constituting the comedo, the initial lesion of acne, - bacterial infections responsible for the hydrolysis of free fatty acids and inflammatory phenomena (papules and pustules).

[0046] The clinical manifestations are characterized by a polymorphic picture. We will focus here on the most frequent forms of acne, namely comedonal, papulopustular and / or nodular acne.

[0047] Retention lesions can be of the open or closed comedo type (microcyst, micro-comedo, white head). Inflammatory lesions derived from retention lesions can be of the papule, pustule type, with indurated nodules, abscesses, fistulas, scarring conditions.

[0048] For the purposes of the invention, the term "skin" is intended to denote the entire epidermis of the human body. More particularly, the skin considered in the present invention is preferably the skin of the face, the décolleté, the back, the scalp and preferably the skin of the face. Figures

[0049] [Fig. 1] Graph showing the prevalence of adult acne in a polluted city (Baoding) compared to a less polluted city (Dalian).

[0050] The present invention will be described in more detail by the examples below. Example

[0051] The example below shows the evidence of the association between chronic exposure to pollution (PAH) and the development of acne-prone skin in individuals exposed to chronic pollution (based on the detection of high levels of pollutants in samples of their hair).

[0052] Material and Method

[0053] Selection of study locations

[0054] Air Quality Index (AQI) data were evaluated for pairs of Chinese cities with the following similar characteristics: cities with similar industrial activity as determined by economic sector (high dependence on manufacturing), latitude (similar UV exposure), geographic area, climate, and population lifestyle (heating and cooking habits, assessed by questionnaire). These similarities allow differences in measured parameters between the two populations to be attributed as much as possible to air pollution. UV Index data for selected locations were also evaluated to determine similar exposure levels.

[0055] The two cities chosen were the most polluted city of Baoding and the least polluted city of Dalian.

[0056] The study locations have been previously described (Palazzi P, et al. Exposure to polycyclic aromatic hydrocarbons in women living in the Chinese cities of Baoding and Dalian revealed by hair analysis. Environ Int. 2018;121(Pt 2):1341-54.). The cities of Baoding (latitude 38.85°N) and Dalian (latitude 38.92°N), approximately 500 km apart in northern China, were selected as study locations. Between June 2014 and June 2015, AQI values ​​above 100 were recorded for 270 days in Baoding and for 83 days in Dalian. Analysis of UV index data for the past 15 years (2002-2017) indicated similar exposure levels for Baoding and Dalian, with typical peak levels from May to July. Dalian has a slightly more humid climate (relative humidity 50-90%) compared to Baoding (40-80%), likely influenced by its coastal location.The respective wind conditions differ slightly between the two cities, but precipitation levels in 2015 were found to be similar. Data evaluated for 2016 showed no other differences in meteorological parameters between the two cities. The populations of Baoding and Dalian are 11 million and 6 million, respectively. Both cities have their economic activities driven by the secondary sector, i.e., industry and construction as the main source of activity.

[0057] Subjects

[0058] Eligible subjects were healthy women, aged 25 to 45, who had resided for at least 15 years in their current city of residence (Baoding or Dalian), had an indoor occupation, were non-smokers or had quit smoking for more than 5 years previously, and who had natural hair. Excluded were women who had chemically treated hair (perm, coloring, straightening), were pregnant, or had skin conditions or prescription medications that might interfere with the study or the health of the subject in the opinion of the investigator.

[0059] Study protocol

[0060] The study was conducted over 2 consecutive weeks for each city to avoid seasonal effects, and outside the peak urban air pollution periods between October and November 2015. Subjects were asked to follow a 3-day wash-out period and received soap and associated instructions. Subjects were assessed with bare skin, i.e., free of cosmetic products, after 15 minutes of acclimatization in a controlled climate (temperature 22 ± 2°C and humidity approximately 50 ± 10%). The multiparametric investigation was carried out in situ by a dermatologist in both cities.

[0061] Skin assessments

[0062] The clinical parameter of acne was assessed on a 4-grade scale (not at all, slightly, moderately to very) by a dermatologist.

[0063] Current acne was measured, and when acne was present, the type of acne (retentional, inflammatory), severity (none at all, mildly, moderately to very severe), and the presence of acne scars (pigmented or not) were determined.

[0064] Standardized images were captured by Visia-CR™ for all women. Standard light with flash was used to better appreciate acne.

[0065] Detection of polycyclic aromatic hydrocarbons in hair

[0066] For each individual, only the first 12 cm (starting from the scalp) were used for analysis. Based on an average growth of 1 cm per month for human hair (Kintz P, Salomone A, and Vincenti M. Hair analysis in clinical and forensic toxicology. Academie Press, Elsevier; 2015), 12 cm corresponded to the 12 months preceding the hair sampling.

[0067] After decontamination to remove particles and chemicals possibly deposited on the hair surface, hair samples were extracted and analyzed according to previously published methods (Appenzeller BMR, Mathon C, Schummer C, Alkerwi A, and Lair ML. Simultaneous determination of nicotine and PAH metabolites in human hair specimen: a potential methodology to assess tobacco smoke contribution in PAH exposure. Toxicol Lett. 2012;210(2):211-9, Grova N, Salquebre G, and Appenzeller BMR. Gas chromatography-tandem mass spectrometry analysis of 52 monohydroxylated metabolites of polycyclic aromatic hy-drocarbons in hairs of rats after controlled exposure. Anal Bioanal Chem. 2013;Sep 7:PMID: 24013637) based on gas chromatography-tandem mass spectrometry (GC-MS / MS).The finally detected biomarker concentration is therefore considered representative of the individual's internal dose, without limited bias due to external deposition. The method made it possible to analyze the parent PAHs (acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo- . b-fluoranthene, benzo-k-fluoranthene, benzo[a]pyrene, indcno| L2,3-[c]pyrcnc, dibenz-ah-anthracene, benzo-ghi-perylene), and monohydroxylated PAH metabolites (1-hydroxy-naphthalene, 2-hydroxy-naphthalene, 9-hydroxy-flurorene, 3-hydroxy-flurorene, 2-hydroxy-flurorene, 4-hydroxy-phenanthrene, 9-hydroxy-phenanthrene, 1-hydroxy-anthracene, 3-hydroxy-phenanthrene, 1-hydroxy-phenanthrene, 2-hydroxy-phenanthrene, 3-hydroxy-fluroanthene, 1-hydroxy-pyrene, 2-hydroxy-benzo[c]phenanthrene, l-hydroxy-benz[a]anthracene, 4-hydroxy-chrysene, 6-hydroxy-chrysene, 11-hydroxy-benz[a]anthracene, 2-hydroxy-benz[a]anthracene, 3-hydroxy-benzo[c]phenanthrene, 8-hydroxy-benz[a]anthracene, 5-hydroxy-benz[a]anthracene, 3-hydroxy-chrysene, 1-hydroxy-chrysene, 4-hydroxy-benz[a]anthracene, 3,9-hydroxy-benz[a]anthracene, 2-hydroxy-chrysene, 8-hydroxy-benzo-b-fluoranthene, 1,7-hydroxy-benzo-b-fluoranthene,12-hydroxy-benzo-b-fluoranthene, 8-hydroxy-benzo-k-fluoranthene, 9-hydroxy-benzo-k-fluoranthene, 7-hydroxy-benzo[a]pyrene, 9-hydroxy-benzo[a]pyrene, 6-hydroxy-indeno[l,2,3-C6?]pyrene, l-hydroxy-indeno| l,23-« / ]pyrenec, 8-hydroxy-indeno[l,2,3-ct / ]pyrene) plus nicotine and cotinine. For the parent PAH, the detection limit ranged from 0.01 pg / mg for benzo[a]pyrene to 4.2 pg / mg for phenanthrene. For PAH metabolites, the detection limit ranged from 0.014 pg / mg for 3OH-phenanthrene to 3.79 pg / mg for lOH-indeno[l,2,3-cd]pyrene.

[0068] Statistical analysis

[0069] The number of women in each city was determined based on the results of the Mexican study (Lefebvre MA, et al. Evaluation of the impact of urban pollution on the quality of skin: a multicentre study in Mexico. Int J Cosmet Sci. 2015;37(3):329-38). Consequently, a sample of 100 women per city was considered sufficient to achieve the objectives.

[0070] The PAH data were summarized by a score, the first principal component of a principal component analysis on the log-normalized PAH measurements. This score is the best summary of the PAHs, i.e., the variable most correlated with all PAHs.

[0071] Acne prevalence was compared based on PAH level (< median PAH score vs > median PAH score) using a Chi2 test.

[0072] A significantly higher prevalence of acne was observed in women with PAH levels above the median (64.7% vs 51.0%; p=0.047).

Claims

Claims

1. In vitro method for prognosis or diagnosis of acne-prone skin of a subject, linked to chronic exposure to pollution, comprising a step (a) of determining, in a sample of one or more hairs of said subject, the level of at least one marker chosen from the group consisting of polycyclic aromatic hydrocarbons, the level of said at least one marker in the sample is the mass concentration of said at least one marker in the sample.

2. A method according to claim 1, wherein the polycyclic aromatic hydrocarbons are selected from acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluo-ranthene, pyrene, benz[a]anthracene, chrysene, benzo-b-fluoranthene, benzo-k-fluoranthene, benzo[a]pyrene, indeno[l,2,3-cd]pyrene, dibenz-ah-anthracene, benzo-ghi-perylene.

3. A method according to any preceding claim, wherein the level of said at least one marker is measured by gas chromatography coupled with mass spectrometry (GC-MS).

4. Method according to any one of the preceding claims, wherein said sample of one or more hairs is one or more strands of hair taken non-invasively from said subject, in particular having a length of approximately 12 cm from the root of the hair(s).

5. A method according to any preceding claim, further comprising the steps of: (b) comparing the level of said at least one marker measured in step (a) with a control, and (c) based on the comparison of step (b), determining whether the subject, in particular the subject's skin, has or is likely to develop acne-prone skin.

6. Method according to the preceding claim, in which the control is a reference value, preferably determined by the average value of the level of said marker in a determined population, even better, the average value of the level of said marker in a population of subjects, in particular subjects, living in a lightly polluted city, in particular a city having an air quality index of less than 100 for less than 100 days, in particular less than 85 days, over a year.

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