INTRODUCTION:

In general, skin types are classified into three types according to an individual’s subjective judgment, as: oily, normal, or dry facial skin types. Another skin type has been added to these skin types, the combination skin type, which means that the individual shows regional differences in type (1–3). There are two types of glands housed within the skin oil glands and sweat glands. The duct of each oil gland usually opens into one hair follicle, but in some locations, there maybe more oil glands per follicle, resulting in greater oil (sebum) secretion in that area. Sebaceous glands occur in the skin of every part of the body except on the palms and soles. Sebum is slightly acidic (pH between 4.2 and 5.6). In both sexes the sebaceous glands are strongly influenced by male hormones, and are most sensitive to these at puberty, particularly on the face and trunk (the acne areas).

The oily appearance of skin results from an excess of sebum excretion and spreading over the body surface and its interaction with the skin surface (4). Oily skin (sometimes called seborrhoeic skin) generally appears at puberty although in a few people it starts much earlier, from the age of six upwards. It is rare after the age of 35. It involves only the upper part of the body, where greater numbers of sebaceous glands are found. This type of skin is particularly common in

adolescents and young adults. At this age there is in both sexes a dramatic increase in sebum production under the influence of the male sex hormones. The extra sebum gives the skin a shiny appearance, especially on the nose and forehead. Sebum secretions vary individually according to age, sex, inherited traits, and topographical variations of the skin (1). The amount of facial sebum secretion is an important consideration in facial skin care. Both excessive sebum secretion and reduced sebum secretion are cosmetically undesirable. Increased sebum production stimulated by androgens is nearly always the first listed pathogenic factor promoting acne. Acne is a disease of the pilosebaceous unit. The major pathogenic factors promoting acne are increased sebum production caused by androgen action, ductal hypercornification, colonization by Propionibacterium acnes, and inflammation (5-6). Until now most of the studies has been carried out to define only facial skin type on the basis of sebum secretion. Skin is not only a part of face it covers all our body organs and we need to maintain it healthy by means of various cosmetics products. Most of the people totally unaware about their exact skin type because of that they are unable to choose right cosmetic products to maintain their skin healthy. However, an individual’s feelings on the topic of sebum secretion are too subjective, and significant discrepancies exist between such subjective descriptions of skin type and objective measurements (1). Skin type and acne problem varies from community to community, due to different climatic condition, genetic build up and other factors. Present work has been carried out on Indians males and females using the non invasive photometric method (Sebumeter) to: (a) Investigate the anatomical variations of sebum secretion among them (b) Evaluate their skin type of different anatomical region as per sebum secretion (c) Define their final skin type may be different from facial skin (d) Evaluate whether the Subjective skin type description correlates with Sebumeter measurement values (e) Investigate the occurrence of acne at highest sebum secretion anatomical area.

MATERIALS AND METHODS:

Study population

Forty three healthy volunteers (aged 22-35years) were included in the study, after undertaking proper consent. As all studies carried in India so all participated volunteers were Indian. The inclusion criteria used were that subjects were healthy, without any dermatological problems and had no previous treatment history of moderate or severe acne.

Sebum secretion measurements

Sebum secretions were measured using a Sebumeter (SM815, C-K electronics, Cologne, Germany). Seven different anatomical sites of the body were selected; forehead, nose, left and right cheeks, chin, neck and right arm. The Sebumeter SM 815 was calibrated to zero with an unused tape section prior to each measurement. Sebum was collected from each site on a plastic strip using a constant pressure of 10 N for 30 s. Volunteers were asked not to use any cosmetics and not to wash within 4 hr of measurements. All procedures were performed by the same investigator in a room at constant temperature (22°C) and humidity (42%) from July to October 2008, at Institute of Pharmacy, Pt. Ravishankar Shukla University, Raipur, Chhattisgarh (C.G.), India. Study on volunteers carried out according to the Helenski standard guidelines and after taking prior permission from Institutional Ethical Committee.

Sebum secretion amounts were recorded and mean facial sebum excretions (MFSE) (1) were calculated. Measurement areas were classified as follows; high sebum-secreting zone (Tzone; forehead, nose, and chin) and low sebum-secreting zone (Uzone; both cheeks), lowest sebum secreting areas (Lpart; neck and arm) and average of sebum secretion of seven anatomical regions (AVE).

The skin types at individual seven anatomical sites selected for study were determined using the sebum secretion guidelines (manual) supplied with the Sebumeter. However, because these guidelines mentioned as listing the reference values of each measured locations only, they could not be directly applied to the skin types of the Tzone, Uzone, Lpart, average of all (AVE), and whole face (MFSE). Thus, we prepared new sebum secretion reference values for the combined Tzone, Uzone, Lpart, AVE and whole face (MFSE) by calculating the mean value at each location. The reference values used to evaluate the skin types at individual zones are listed in table 1.

Table 1: Reference value for the assessment of skin type by sebum secretion measured with Sebumeter (µg/cm²)

Type	MFSE	Tzone	Uzone	Lpart	AVE
DRY	<88	<100	<70	<28	<60
NORMAL	88-204	100-220	70-180	28-70	60-135
OILY	>204	>220	>180	>70	>135

MFSE (mean facial sebum excretion) = Forehead+chin+nose+left cheek+right cheek/5;

Tzone = Forehead+chin+nose/3;

Uzone= left cheek+right cheek/2;

Lpart(lower part) = neck+arm/2;

AVE (average) = Forehead+chin+nose+left cheek+right cheek +neck+arm/7

Subjective skin type

Before measuring their sebum casual levels, a questionnaire was given to each of the subjects for documenting their subjective skin type. Subjects were asked, ‘‘what do you think your skin type is?’’ and they chose an answer from four choices (dry, normal, oily, and combined). While the questionnaire was being answered, no explanations regarding skin types were provided in order to exclude any influence from the investigators.

Acne observations

Only oily anatomical areas of each volunteer, which were detected after sebum measurement, were observed for occurrence of acne (inflammatory or non-inflammatory) by means of taking photographs using digital camera. Acne lesions were marked with circle and counted down. Digital photographs images were modified using software: Microsoft picture manager version 11.0.

Statistical analysis

The differences of mean sebum casual levels among the seven sites in each population were tested using the ANOVA, after testing for normality using STATS software. The data were considered significant if P < 0.05, unless otherwise noted.

RESULTS:

Topographical variation in sebum secretion

Significant anatomical variations in sebum secretion were observed among all volunteers. Mean amount of regional sebum secretion decreases from chin 126.70±107.73µg/cm², forehead 124.76±63.05µg/cm², nose 118.82±91.93µg/cm², right cheek 116.35±116.98 µg/cm², left cheek 110.64±68.97µg/cm², neck 91.41±71.80µg/cm², to arm 36.47±66.23µg/cm² (Figure 1). The mean and standard deviation of sebum casual levels of the seven studied site as well as the P- values between two sites are listed in table 2. Mean sebum secretion between two sites found to be statistical significance if P<0.05.

Fig. 1 Differences in skin (mean±SD) sebum secretion at various anatomical region

Fig. 2 Mean sebum secretion of volunteers at different zone

There were differences in mean sebum secretion of MFSE, Tzone, Uzone and Lpart (Figure 2). Tzone comprise of highest sebum secreting zone. Tables 3 represent the list of volunteers who possess oily skin at respective anatomical region as per sebum secretion. Volunteer’s anatomical regions comprise either of normal/dry/oily skin, vary from individual to individual. Chin is the anatomical region which was found to be oily between maximum numbers of volunteers (Table 3).

Table 4: Classification of skin type according to the sebum secretion at individual region

Volunteers

Fhead

Chin

Nose

Lcheek

Rcheek

Neck

Arm

AVE

MFSE

Tzone

Uzone

Lpart

Final type

V10

V11

V12

V13

V14

V15

V16

V17

V18

V19

V20

V21

V22

V23

V24

V25

V26

V27

V28

V29

V30

V31

V32

V33

V34

V35

V36

V37

V38

V39

V40

V41

V42

V43

Normal, D = Dry, O = oily, C = Combined, F head = Forehead, Lcheek = left cheek, Rcheek = right cheek

Table 5: Number of volunteers found to be dry, normal and oily skin at different anatomical parts of body

Type	Fhead	Chin	Nose	Lcheek	Rcheek	Neck	Arm
Dry	19	9	19	12	21	16	25
Normal	21	19	20	25	20	20	18
Oily	3	15	14	6	3	7	0
n	43	43	43	43	43	43	43

n = Number of volunteers

Based on MFSE data; 42% of volunteers were found to be dry skin and 58% were found to be normal skin (Table 6). Mean sebum secretion data of Tzone; revealed that 33% of volunteers belongs to dry skin, 56% to normal skin, and 11% to oily skin (Table 6). As per the mean sebum secretion of Uzone and Lower part of the body; 35% and 28% of volunteers hold dry skin respectively, 58% and 67% of volunteers possess normal skin respectively; 7% and 5% of volunteers were found to be oily skin respectively (Table 6). Above data revealed that maximum volunteers belongs to normal type of skin, then dry skin followed by oily skin.

Overall skin type was found to be different as compare to skin type of anatomical region and zones (Table 3 and 4). Out of all volunteers, 54% of them hold normal skin, 10% dry skin and 10% combined skin. Volunteer number seven (V7) was found to possess best skin as only this volunteer share common type of skin (Normal skin) at every anatomical region and zone of the body (Table 4).

Final skin type as per Sebumeter and Subjective analysis

As per the subjective analysis it has been found that out of 43 volunteers, 12 of the volunteers regard their skin as dry type, 8 of them regard their skin as combined type, 15 of them as oily type and 8 of them as normal type. But final type of skin according to datas of quantitative analysis of sebum secretion, out of 43 volunteers, 10 of the volunteers hold dry skin, 23 and 10 of the volunteers were found to possess normal and combined skin respectively. None of the volunteers were found to be oily skin by objective analysis (Table 7). Figure 3 represents the correlation between the subjective and objective skin type evaluation. Comparing final objective (Sebumeter reading) skin type with subjectively described skin type of each volunteer, only 4 (9%) volunteers (V4,V5,V16, V38) shown complete coincidence.

Fig 3 Correlation between subjective and objective skin type

Table 7: Final skin type the basis of objective (Sebumeter) and subjective analysis

Volunteers	Final skin type
Volunteers	Objective	Subjective
V1	N	D
V2	N	D
V3	N	D
V4	C	C
V5	C	C
V6	C	O
V7	N	D
V8	C	O
V9	N	O
V10	D	N
V11	C	O
V12	N	O
V13	D	C
V14	N	O
V15	N	O
V16	N	N
V17	N	C
V18	N	D
V19	N	C
V20	N	D
V21	D	O
V22	C	D
V23	D	N
V24	D	O
V25	N	C
V26	N	O
V27	C	N
V28	N	C
V29	D	N
V30	C	O
V31	N	D
V32	N	N
V33	D	N
V34	D	D
V35	C	O
V36	N	O
V37	N	D
V38	N	N
V39	D	O
V40	C	D
V41	D	D
V42	N	O
V43	N	C

N= Normal, D = Dry, O = Oily, C = Combined

Occurrence of acne

Number of acne lesions had been observed oily in the oily anatomical regions of volunteers. No acne lesions were observed at anatomical regions which found to be dry and normal. Chin is the region where maximum numbers of acne were observed as compare to all other oily regions [Figure 4], all volunteers who hold oily skin at chin part suffers from acne problem. Significant relation were found between mean sebum secretion and mean acne lesions of the chin, however, the correlations (R² = 0.3744) were not strong enough solely to explain the cause of acne associated with the sebum secretion. Modified photographs of some volunteers suffering from acne are shown in figure 5a-5f.

Fig 4 Mean acne lesions and mean sebum secretion at seven studied sites

Fig 5a

Fig 5b

Fig 5c

Fig 5d

Fig 5e

Fig 5f

Fig 5a- 5f Acne lesions observed in oily region of face,

5a) Right cheek of V7; 5b) Left cheek of V14; 5c) Forehead of V17; 5d) Chin of V15; 5e) Nose of V11; Fig 5f) Neck of V37

DISCUSSION:

Variations in sebum secretion have been known to be related with topographic differences, demographic profiles, inherited factors, and environmental factors (7-8). Since sebum secretion is related to the pathogenesis of acne (9) and is important for selecting skin-care cosmetics, several methods of measuring sebum secretion have been developed (4). Skin is major part of the body and choice of cosmetics products must be according to skin type for getting maximum benefit.

It is well known fact that the face has two different areas from the viewpoint of sebum secretion, these are called the T-zone (the high sebum-secreting zone) and the U-zone (the low sebum-secreting zone). Mean sebum secretion of different zones in our study, illustrate that Tzone was found to be the highest secreting zone between Indian people.

In many of the studies the central forehead and nose were considered to be high sebum secreting areas, and the chin and perioral area are also occasionally viewed as a high sebum secreting zone (10). In our study, the mean sebum secretion at chin showed highest levels of sebum secretion than the forehead and nose. Thus, we classified the chin as a high sebum-secreting anatomical region among people of Indian community. Sebum secretion of the forehead, nose and cheek were found to be higher than those of the neck and arm. Arm was the site of lowest sebum secretion. When we studied each individual we found that chin was not only the region for higher sebum secretion, highest sebum secretion areas varies person to person. In this study, sebum secretions showed definitive regional differences [Table 2]. This variability exists because of differences in genetic factor and hormone release and hence final type of skin for each volunteer came out to be different. According to sebum secretion one can posse’s oily/normal/dry skin at different anatomical region and different zones, but its over all type of skin can be either normal/dry/combined/oily (Table 2). Volunteer 7 is the only one who owns normal skin at every anatomical region of the body. Maximum number of volunteer enjoys normal skin, which may be due to the demographic profiles, inherited factors, and environmental factors.

The concept of skin type has formed by several distinct clues (11) because of that most of the people are not able to tell their exact skin type. That’s why we carried out the subjective (Questionnaire) and objective (Sebumeter measurement) analysis of skin. Volunteer number seven from so long treating its skin as dry but our study revealed the exact type of its skin (i.e Normal). Our results showed a greater variation between objective skin type and subjective skin type. Those who thought they are having dry skin actually they holds a normal skin and vice versa. Objective study revealed the exact skin type of volunteer on the basis of quantitative evaluation of sebum secretion. As in lack of knowledge about which skin they really posses they have been unable to use correct cosmetic product so long. Moreover, some of the volunteers regard their skin as oily as they experienced greasiness in their skin, but when Sebumeter reading revealed that the greasiness that they felt due to sebum secretion was in control amount not coming in the range of oily skin. So by our investigation we revealed that which anatomical region of their body is secreting highest sebum and comprising of which type of skin. Considering sebum secretion at selected anatomical region and mean sebum secretion of the different zone, we finally assessed the final skin type of volunteers [Table 3 and Table 4]. By this they can apply cosmetics according to their skin and enjoy maximum benefits.

Increased sebum production stimulated by androgens is nearly always the first listed pathogenic factor promoting acne. However, facial sebum secretion depends upon the topography of the face. In our investigation we were found that, those volunteers posses oily skin at anatomical region suffered from acne problem. Results revealed that dry and normal part of the skin were totally free from acne. Mean acne lesions and mean sebum secretion revealed that chin is the highest sebum secretion [126.70] anatomical area, where the occurrence rate of acne had been found highest [Figure 4]. But, present study revealed that acne lesions were associated with the oily areas (high sebum secretion) of the skin and not with the dry and normal areas of skin. Data of MFSE, obtained in our study revealed the dependency of acne occurrence upon the amount of sebum secretion at different anatomical region.

Over all study demonstrate that in Volunteers (Indians) chin is the high sebum secreting Tzone and maximally affected anatomical region by acne attack. Hence, among Indian community high sebum secretion considered to be a major component to cause acne. Therefore, quantitative evaluation of sebum secretion may aid the consumer to let know when the anti-acne cosmetic products are selected in subjects with acne, rather then solely depending on the subjective feelings of Consumer.

CONCLUSION:

While the state of skin, good or bad, has much to do with heredity, hormones and lifestyle, keeping it clean and protected plays a very important part in its surface condition and long-lasting looks. Nothing remains static on the skin front seems to vary from day to day, certainly from season to season, community to community, individual to individual. Most important is to maintain the skin healthy and beautiful by means of Cosmo-dermatological products. And it impossible until one is aware about its exact type of skin. Present work assist the consumer to opt either the same or different lotions/creams/gels for their facial and body skin according to their skin type. In conclusion this study shown that Subjective feeling is not a reliable method to judge about ones skin type, skin type should be define in a scientific way to provide an objective guideline to help people care for healthy skin. Quantitative estimation of sebum amount at the skin surface may well assist in the development of sebosuppressive cosmetic agents to help the reduction of the skin greasiness and improve acne.

ACKNOWLEDGMENTS:

The authors acknowledged University grant commission [F. No.32-133/2006(SR)], New Delhi for financial assistance. One of the authors show her gratitude towards the head of the cosmetic lab, institute of pharmacy, Pt, Ravishankar Shukla University, Raipur (C.G.) for providing facilities to carry out research work.

REFERENCES:

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3. Le Fur, I. et al, 1999. Comparison of cheek and forehead regions by bioengineering methods in women with different self reported ‘‘cosmetic skin types’’. Skin Res. Technol., 5: 182-188.

4. Pierard, G. E. et al, 2000. EEMCO Guidance for the in vivo Assessment of Skin Greasiness.
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Received on 23.12.2012 Accepted on 26.12.2012

Res. J. Topical and Cosmetic Sci. 3(1): July-Dec. 2012 page 48-55

Mean±SD (µg/cm²)	Fhead (124.76± 63.05)	Chin (126.70± 107.73)	Nose (118.82± 91.93)	Lcheek (110.64± 68.97)	Rcheek (116.35± 116.98)	Neck (91.41± 71.80)	Arm (36.47± 66.23)
Fhead		P <0.05	P <0.05	P >0.05	P <0.01	P >0.05	P >0.05
Chin			P >0.05	P <0.05	P >0.05	P <0.05	P <0.05
Nose				P >0.05	P >0.05	P >0.05	P >0.05
Lcheek					P <0.05	P >0.05	P >0.05
Rcheek						P <0.05	P =0.01
Neck							P >0.05

Skin type	Dry	Normal	Oily	Combined	Total volunteers
Facial skin as per MFSE	18(42%)	25(58%)	0(0%)	0(0%)	43(100%)
Skin type as per T zone	14(33%)	24(56%)	5(11%)	0(0%)	43(100%)
Skin type as per Uzone	15(35%)	25(58%)	3(7%)	0(0%)	43(100%)
Skin type as per Lpart	12(28%)	29(67%)	2(5%)	0(0%)	43(100%)
Final type of skin(Sebumeter)	10(23%)	23(54%)	0(0%)	10(23%)	43(100%)