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Clay mineral facial masks are used to treat some dermatological diseases, just for cleansing or reduce the amount of oil secreted by sebaceous glands. There are several types of clays, which vary in mineralogical and chemical composition, color and origin. However, the literature lacks studies involving clay facial masks, in particular regarding their influence on skin´s biomechanical properties. Thus, this work aimed to characterize colored clays and evaluate its influence on skin firmness and elasticity by a short-term clinical study. Different clays (named in this study magnesium aluminum silicate - MAS, white, pink and green) were chemically characterized, and facial mask formulations were prepared. The short-term clinical study was performed through the application of formulations on the skin. The skin firmness and elasticity were assessed before treatment and after mask removal. The statistical analysis showed no significant influence of time or formulations in those parameters, although volunteers reported the sensation of mechanical tension after the removal of the clay facial masks. Thus, the composition of the different clays did not affect the skin viscoelasticity behavior in the short-term clinical study, and a long-term use of this type of formulation must be indicated to observe all the expected benefits.
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Revista de Ciências
Farmacêuticas
Básica e Aplicada
Journal of Basic and Applied Pharmaceutical Sciences Rev Ciênc Farm Básica Apl., 2016;37(1)
ISSN 1808-4532
Autor correspondente: Michelli F. Dario, Department of Pharmacy, School
of Pharmaceutical Sciences of University of São Paulo, São Paulo-SP, Brazil.
E-mail: michelli.dario@usp.br
Characterization and Short-Term clinical study of clay
facial mask
Maria Valéria R. Velasco1; Vivian Zague1; Michelli F. Dario*1; Deborah O. Nishikawa1; Claudinéia A.S.O. Pinto1; Mariana
M. Almeida1; Gustavo Henrique Goulart Trossini1; Antonio Carlos Vieira Coelho2; André Rolim Baby1
1Department of Pharmacy, School of Pharmaceutical Sciences of University of São Paulo, São Paulo-SP, Brazil;
2Department of Metallurgical and Materials Engineering, Escola Politécnica, University of São Paulo, São Paulo-SP, Brazil.
ABSTRACT
Clay mineral facial masks are used to treat some
dermatological diseases, just for cleansing or reduce
the amount of oil secreted by sebaceous glands. There
are several types of clays, which vary in mineralogical
and chemical composition, color and origin. However,
the literature lacks studies involving clay facial masks,
in particular regarding their inuence on skin´s
biomechanical properties. Thus, this work aimed to
characterize colored clays and evaluate its inuence
on skin rmness and elasticity by a short-term clinical
study. Dierent clays (named in this study magnesium
aluminum silicate - MAS, white, pink and green) were
chemically characterized, and facial mask formulations
were prepared. The short-term clinical study was
performed through the application of formulations
on the skin. The skin rmness and elasticity were
assessed before treatment and after mask removal.
The statistical analysis showed no signicant inuence
of time or formulations in those parameters, although
volunteers reported the sensation of mechanical tension
after the removal of the clay facial masks. Thus, the
composition of the dierent clays did not aect the skin
viscoelasticity behavior in the short-term clinical study,
and a long-term use of this type of formulation must be
indicated to observe all the expected benets.
Keywords: Clay. Biomechanical properties. Chemical
characterization. Facial mask. Clinical study.
INTRODUCTION
Clay minerals are used by pharmaceutical or
cosmetic industries for several proposes like excipients,
due to its rheological properties, or as substances with
interesting biological activity in function of its chemical
composition (Lopez-Galindo et al., 2007; Viseras et al.,
2007; Zague et al., 2007). Among all possibilities, clays
are necessary for the cosmetic industry since they present
interesting characteristics such as easiness of application
and removal, reduced time for drying and hardening, and
dermatological innocuousness (Carretero, 2002; Toedt et
al., 2005).
Their use as a facial mask may be done directly on
the skin at room temperature (kaolinite or smectites mixed
with water). But, to treat dermatological diseases such as
blackheads, spots, acne and seborrhoea it is recommended
the application of a mixture comprised of clays and water
in a high temperature. The heat increases perspiration and
sebaceous secretions while it also opens the pilosebaceous
orices and activates the metabolic change and the
excretion of catabolites (Carretero, 2002).
Clay mineral used by the industry typically have
a natural origin, although several of these minerals may
also be obtained by synthesis. The synthetic clay minerals
available in the market has specic properties and uses and
has a higher cost compared to natural minerals (Carretero
& Pozo, 2009). They belong to the phyllosilicates family
of compounds consisting of aluminosilicates containing
considerable amounts of K, Mg, Ca, Na and Fe. Also
Ti, Mn or Li may be present in smaller quantity. The
family of phyllosilicates is divided into various groups
of minerals, each group containing several species. In all,
there are dozens of phyllosilicates, ranked according to
their crystalline structure, chemical (composition, surface
chemistry, and charge layer) and physical (morphology and
particle size) properties (Bergaya & Lagaly, 2006; Lopez-
Galindo et al., 2007).
In industrial applications some types of clays can be
distinguished: (i) white, (ii) bentonite, (iii) talc, (iv) brous
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Clay facial Mask: Clinical study
Rev Ciênc Farm Básica Apl., 2016;37(1)
clays (palygorskite and sepiolite), and (v) ‘common clays’
(largely used for traditional ceramic products) which often
contain kaolinite and illite/smectite mixed-layer minerals
(Bergaya & Lagaly, 2006; Lopez-Galindo et al., 2007).
Kaolin (also called ‘china clay’) is a soft clay that
is an essential component in the manufacture of porcelain.
Also, it is widely used in the industry of paper, rubber,
paint, pharmaceuticals, cosmetics and many other products.
Kaolinite is the most common mineral, so kaolin and
kaolinite are therefore frequently confused as synonymous
terms. Kaolins are usually white, but may also have light
shades of brown, cream, yellow, red or gray.
The term bentonite, which is very frequent in the
technical vocabulary as well as in dierent pharmacopeias,
is used to designate any plastic, colloidal, swelling clay,
basically consisting of a mineral of the smectite group
(montmorillonite, saponite or hectorite), with no regard
for its origin. Bentonites may have several colors (white,
yellow, brown, green, pink, red or black) according to
the ions in the smectite structures and according to the
associated minerals existing, both related to their origin.
Talc is a clay mineral that chemically is not an
aluminosilicate, but a mineral composed of a hydrated
magnesium silicate with a crystal structure similar to the
smectite structure, but with no layer charge. Talc is usually
white or near (greenish or grayish) white. Its particles
have a aky habit and are easily milled, becoming a bright
white, unctuous micronized powder. It is widely used in
the industries of polymeric and painting products as llers,
and in ne and technical ceramics, pharmaceuticals and
cosmetics.
Fibrous clays include two minerals: palygorskite
(also known as attapulgite) and sepiolite. Unlike other
clay minerals that have a at crystal habit, sepiolite and
palygorskite have a brous morphology. These clay
minerals occur as ne, white (or near white)-colored
particles that are composed of bundles of microscopic
bers. When those particles are micronized, the resulting
material is easily dispersed in water and other polar liquids,
forming a large volume network of interlaced bers that
traps all the dissolvent, leading to dispersions with high
viscosity.
‘Common clays’ are composed of mixtures of clay
minerals (which often contain kaolinite and illite/smectite
mixed-layer minerals) with a wide range of associated
minerals (quartz, oxides, and hydroxides of iron and
aluminum, calcium carbonate, among others). ‘Common
clays’ are largely used only for traditional ceramic products
as bricks and tiles (Bergaya & Lagaly, 2006; Lopez-Galindo
et al., 2007).
Each clay with potential cosmetic applications has
a specic dermatological indication that could ideally be
related to the type of clay (chemical composition, crystal
structure, the presence of associated minerals) and its eect
on the skin. These clays are usually identied by their colors
by the market. However, information is rare regarding a
characterization of each of these colored clay allowing
a correlation with dermatological indications. What is
commonly found are useful but incomplete information
such as yellow clay is used against bacterial infections, red
for skin cleansing, blue is eective against acne, green used
to reduce the amount of oil secreted by sebaceous glands
while black may be indicated for general skin nourishment
(Mpuchane et al., 2010).
The interest in developing clay facial masks is
assigned to cleansing and lifting eects (Khanna &
Datta Gupta, 2002). However, the literature lacks studies
involving clay facial masks, in particular regarding their
inuence on skin´s biomechanical properties. This work
aimed to characterize colored clays and evaluate the
rmness and elasticity of the skin at dierent time intervals
after application of clay facial masks.
MATERIAL AND METHODS
Characterization of clay minerals
Chemical composition
The qualitative mineralogical composition of
commercially available clays (MAS, white, pink and
green), purchased from Terramater, was determined using
X-ray diraction (XRD). Clay diraction patterns were
obtained in X-ray diractometer Bruker AXS D5000. The
results were analyzed in software Dirac Plus version 7.1
and compared with diraction patterns compiled in the
database Powder Diraction File. A voltage of 40 kV and a
current of 40 mA using a CuKα radiation were used. Scans
were stepwise from 3° to 65° with a step of 0.05° (2θ) and
a step time of 1 s.
Chemical analysis was performed in X-ray
uorescence spectrometer Philips PW2400 XRF. 2.0 g of
each clay sample were rst dried in porcelain crucibles
at 105° C for at least 3 h. Then 10.0 g of 4:1 lithium
metaborate: lithium tetraborate commercial ux (Claisse
eutectic mixture of 20% lithium tetraborate and 80%
lithium metaborate), previously heated to 600° C, was
added (Mori et al., 1999) to prepare the glass disc used in
the analysis. The results were given in percentage for most
of the elements and in ppm for those below 1000 ppm.
pH values
The pH measurements of the clay dispersions were
obtained in pHmeter 8417 Hanna, at 22.0 ± 2.0° C. Each
clay was dispersed (1:10) in neutralized distilled water (pH
= 7.0) and then ltrated through a qualitative lter paper.
Clay facial masks composition
The quantitative composition (% w/w) of the
developed base formulation is described in Table 1. All
ingredients were pharmaceutical grade, used as received
from commercial sources, without any further purication.
The magnesium aluminum silicate clay (MAS) was used as
gelling, emulsifying and suspending of the formulations.
Thus, three dierent clays (white, pink and green) were
incorporated and tested, generating four formulas including
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Clay facial Mask: Clinical study
Rev Ciênc Farm Básica Apl., 2016;37(1)
the base. The pH of the formulations was adjusted to 5.5 to
6.5 with triethanolamine or citric acid 10% (w/v) according
to the need.
Skin viscoelasticity assessment
This study was held in open, control intra-individual,
complete block and approved by the Ethics Committee
(Process CEP 175-06).
Eight healthy Caucasian female volunteers ages
20–30 years (mean ± SD, 25 ± 4.4 years) participated in
the study after giving informed consent. Subjects with
dermatological abnormalities (e.g., rashes, wounds, scars)
in the test areas were excluded. The restrictions imposed
on volunteers were: no application of dierent products in
the experimental area, no allergen, anti-inammatory or
vitamin A acid and derivatives treatment during the study.
Also, the experimental area should not have contact with
clothes during the study or between the start and the end
of the measures. Subjects who were pregnant or taking
hormone replacement or corticosteroids therapy were also
excluded.
The subjects were asked to refrain from using
moisturizers on the test sites for 24 h before the study
and from applying water to the sites at least 3 h before
evaluations. Biophysical measurements were made while
volunteers were prone and at least 30 min after acclimation
to the room environment (20.0 ± 2.0º C and 40.0 ± 5.0%
relative humidity).
An amount of 3.0 g of each formulation were
applied randomly on the delimited area of 30 cm2 (5 x 6
cm) on the right or left forearm, on ve areas-test and a
control area (without formulation) (Bazin and Fanchon
2008). Application time was 20 min, and the removal was
performed by paper towel dampened with distilled water.
Skin viscoelastic parameters were evaluated by
using a Cutometer® (SEM 575; Courage &Khazaka
Electronic GmbH, Cologne, Germany). It measures the
vertical deformation of the skin when it is pulled using
a controlled vacuum into the circular aperture. The time/
strain mode was used with ve consecutive cycles of a 5
s suction application followed by a 3 s relaxation period.
A 2 mm diameter measuring probe and constant suction
of 500 mbar were applied. The skin rmness and elasticity
were assessed before treatment (T0) and 20 min, 1 h, and
2 h after mask removal. The parameters M1 (maximum
extensibility, meaning skin rmness) and M2 (deformation
compared to the initial condition, represents cutaneous
elasticity) were expressed at each time of the experiment
as an absolute value. The lower M1 and M2 represent the
higher cutaneous rmness and elasticity, respectively, and
vice-versa (Velasco et al., 2014).
Statistical analysis
Triplicate data from each site were averaged. The
statistical analysis was carried out by longitudinal mixed
model, considered as a random eect of the voluntary since
formulations and test time were considered xed.
RESULTS AND DISCUSSION
Clay mineral characterization
The composition of clay minerals inuences their
properties, and also the pH of the formulation. As shown
in Table 2, clays show neutral pH, except for the green
one that was around 9.0, due to the presence of calcium
carbonate (calcite) in its composition. The mineralogical
and chemical compositions of clays are shown in Figure 1
and Table 3, respectively.
Table 2. pH values of clay minerals. Legend: MAS =
magnesium aluminum silicate
Clay MAS white pink green
pH 6.5 ± 0.5 7.0 ± 0.0 7.2 ± 0.1 8.7 ± 0.1
Figure 1. Mineralogical composition of clays obtained by
X-ray diraction. Legend: k = kaolinite; qz = quartz; ca =
calcite; m = mica group; mu = mullite; s = smectite group.
Clays are mainly composed of clay minerals but
may present associated minerals such as quartz and calcite
in function of their natural composition or industrialization
processes, becoming residual materials (Besq et al., 2003).
The XRD pattern of green clay (Figure 1) shows sharp
peaks related to quartz and calcite, and also very reduced
peaks referring to kaolinite and a mica group mineral. The
presence of calcite raises the pH value of its dispersion
in water to values around 9.0. Thus, the neutralization of
Table 1. Qualitative and quantitative (% w/w) formulation
composition. *International Nomenclature of Cosmetics
Ingredients (Personal Care Products Council 2016);
*Phenoxyethanol; Methylparaben; Ethylparaben;
Butylparaben; Propylparaben; Isobutylparaben.
Ingredients (INCI*) % (w/w)
Magnesium aluminum silicate 5.0
Xanthan gum 0.5
Colored clay 30.0
Glycerin 4.0
Propylene glycol 4.0
Preservatives* 0.5
Distilled water 56.0
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Clay facial Mask: Clinical study
Rev Ciênc Farm Básica Apl., 2016;37(1)
cosmetic formulations containing green clay is necessary
since the skin physiological features slightly acidic pH (5.5
to 6.5) (Rippke et al., 2002). After the pH neutralization,
calcite is eliminated (releasing carbonic gas) and quartz
becomes the main component.
On diractogram of white clay, characteristic peaks
of kaolinite were observed, some associated minerals are
also identied: quartz, a mica group mineral (probably illite)
and mulite. The identication of mullite is a signal that this
clay sample is a mixture of natural clay and a calcined one
because mullite is a high-temperature phase obtained by the
calcination of white.
The main clay mineral present in pink clay is kaolinite
as demonstrated in its XRD pattern. Quartz, a micaceous
phase (probably illite) and an iron oxide (hematite) are
present as associated minerals in this clay.
The main peaks of MAS’s XRD pattern are
characteristic of a clay mineral of the smectite group, which
confers its peculiar rheological properties. No associated
minerals are clearly identied. The MAS clay is designated
chemically in the pharmaceutical eld as “magnesium
aluminum silicate”, which corresponds to a mixture of
montmorillonite and saponite (both belonging to the smectite
group). It was used in this study as gelling, emulsifying, and
suspending in the formulations.
Although commercial clays are subjected to
purication processes, the green, white and pink clays used
in this study presented associated minerals. In the case of
the white clay, one of those minerals (mullite) is not natural,
indicating probably an industrial contamination of the
sample. Unfortunately, the presence of these minerals can
negatively impact the clay’s properties and also the stability
of cosmetic preparations (Besq et al., 2003).
Chemical data (Table 3) indicate a high content
of CaO (9.46%) on the green clay due to the presence of
the mineral calcite in its mineralogical composition. The
smectite present in the MAS can be considered Na-Mg type
since the chemical analysis showed 2.5% MgO and higher
content of Na2O, in relation to the CaO (Na2O/CaO = 1.21).
The ratio Na2O/CaO is an important parameter to evaluate
the nature of clay minerals of the smectite group, since high
ratios of Na2O/CaO (1 to 3) indicate the presence of swelling
smectite, while low ratios (less than 1) is typical of non-
swelling clay of type 2:1 (Cara et al., 2000). Therefore, the
ratio equal to 1.21 (Na2O/CaO) justies the use of MAS as
a gelling agent and thickener in cosmetic formulations. The
pink clay shows a high content of Fe2O3 (6.89%) due to the
presence of iron oxide (probably hematite), responsible for
its color. Green clay also has a high iron content (5.73%),
but its color cannot be attributed unambiguously to an iron
oxide or hydroxide, once the existence of iron green crystal
phases is not common and the presence of such phases was
not observed in the XRD curve. Green color could also
be due to calcite, which can display up green color when
contaminated with a serpentine. However, a serpentine also
was not identied from XRD pattern. Therefore, likely due
to the low crystallinity of the associated phases present in
the green clay, which prevents the identication by XRD,
it was not possible to explain the reason for its green color
unambiguously.
Clay facial mask ecacy
Clays are mostly used in facial masks due to their
high absorbency levels on the skin surface, such as greases,
toxins and even bacteria and viruses (Carretero, 2002).
Nevertheless, the tightening eect is also expected for
clay facial masks, in function of the product hardening and
contraction, after evaporation of water from the preparation,
which causes a sensation of mechanical stress (Wilkinson
& Moore, 1982; Ganey, 1992; Carretero, 2002). Also, the
chemical and mineralogical composition may inuence their
eect on the skin. For example, red clay is recommended
for dry skin and green clay, for oily skin (Reinbacher, 2002).
However, no scientic literature correlates the color of clays
with dierent eects on the skin (Allo & Murray, 2004).
According to the results observed in Figure 2 and 3,
the treated and control areas showed slight changes in the
M1 and M2 values, at dierent times. The decrease in M1
and M2 values involves an increase of skin rmness and
elasticity, respectively. However, statistical analysis showed
no signicant inuence (p > 0.05) of time or test formulations,
including the control area, as well as the interaction between
these factors, in the elasticity parameter (M2).
Figure 2. Inuence of clays on M1 (skin rmness) parameter.
Table 3. Clay’s chemical composition obtained by X-ray
uorescence. Amounts are expressed in % for smaller
elements (<0.1) and higher (> 0.1) and in ppm (<1000) for
the trace elements. Legend: Loi = loss on ignition; MAS =
magnesium aluminum silicate
Chemical
composition
Clay type
MAS Green Pink White
SiO267.05 50.80 48.63 49.76
Al2O314.91 14.51 30.86 40.76
MnO 0.03 0.06 0.01 0.03
MgO 2.50 2.39 0.17 0.04
CaO 0.93 9.46 0.75 0.13
Na2O 1.59 0.02 <0.02 <0.02
K2O 1.31 3.97 1.80 1.30
TiO22.43 0.78 0.20 0.53
P2O50.02 0.13 0.25 0.06
Fe2O3 1.85 5.73 6.89 1.30
Loi 6.90 12.05 9.85 4.73
Na2O/CaO 1.21 0.01 <0.03 <0.15
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Clay facial Mask: Clinical study
Rev Ciênc Farm Básica Apl., 2016;37(1)
Figure 3. Inuence of clays on M2 (cutaneous elasticity)
parameter.
Although volunteers reported the sensation of
mechanical tension after the removal of the clay facial
masks (t = 20 min), the statistical analysis of M1 values
showed no signicant dierence (p > 0.05) in comparison
with T0. Thus, the nowadays available equipment is not
enough to detect the tensor eect felt by volunteers.
The main eect of clay facial masks, in a short-
term application, comes from hardening and contraction
of the product after the evaporation of water, which is felt
as mechanical stress. Also, clays form a lm on the skin’s
surface which reduces the loss of natural moisture reducing
the transepidermal water loss (TEWL), promoting high
skin hydration, that can be felt by volunteers as raising in
mechanical tension (Berardesca et al., 2012). Therefore, it
was expected to observe increment in rmness 20 min after
mask removal, due to the immediate eect of clay mask
on skin, but this was not observed in this study. This time
was set with the intention to ensure drying of the skin after
removal of the product with distilled water because it could
interfere with the skin properties evaluated.
Thus, the composition of the dierent clays did not
inuence the skin viscoelasticity behavior in the short-term
clinical study. The long-term use of this type of formulation
probably would have more benets because it was already
demonstrated that the clay application in rats for 7 days
increased the numbers of collagen bers (Valenti et al.,
2012), which could decrease wrinkles and increase the skin
rmness.
CONCLUSIONS
The chemical and mineralogical composition of
the dierent clays tested in this study (white, green and
pink) did not inuence the skin biometric proles because
rmness and elasticity were not aected in a short-term
application. Thus, a long-term study is essential to establish
the ecacy and mechanism of action of this type of facial
mask.
ACKNOWLEDGMENTS
We thank Vânia Aparecida Nilsson for the statistical
data analysis, to EVIC Brazil for the cooperation agreement
and to Conselho Nacional de Desenvolvimento Cientíco e
Tecnológico (CNPq) for nancial support.
RESUMO
Caracterização e estudo clínico de curta duração de
máscara facial argilosa
Máscaras faciais argilosas são utilizadas para tratar
algumas doenças dermatológicas, apenas para a
limpeza ou reduzir a quantidade de óleo secretado pelas
glândulas sebáceas. Existem vários tipos de argilas, que
variam em composição mineral, química, cor e origem.
No entanto, a literatura carece de estudos envolvendo
máscaras faciais argilosas, em particular em relação a
sua inuência nas propriedades biomecânicas da pele.
Assim, este trabalho teve como objetivo caracterizar
argilas coloridas e avaliar sua inuência sobre a rmeza
e elasticidade da pele por meio de um estudo clínico de
curto prazo. Diferentes argilas (chamadas neste estudo
de silicato de alumínio e magnésio - MAS, branca,
rosa e verde) foram caracterizadas quimicamente, e
formulações de máscaras faciais foram preparadas.
O estudo clínico de curto prazo foi realizado por
meio da aplicação das formulações na pele. A rmeza
e elasticidade da pele foram avaliadas antes do
tratamento e após a remoção da máscara. A análise
estatística mostrou nenhuma inuência signicativa
do tempo ou das formulações nesses parâmetros,
embora os voluntários tenham reportado sensação de
tensão mecânica, após a remoção das máscaras faciais
argilosas. Assim, a composição das diferentes argilas
não afetou o comportamento visco-elástico da pele no
estudo clínico de curto prazo, e uma utilização de longa
duração poderia ser indicada com a nalidade de se
observar todos os benefícios esperados.
Palavras-chave: Argila. Propriedades biomecânicas.
Caracterização química. Máscara facial. Estudo clínico.
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Received on November 22th 2015
Accepted on October14th 2016
... Mineral tanah liat telah digunakan oleh industri farmasi dan kosmetik untuk beberapa penggunaan seperti eksipien, karena sifat reologisnya, atau sebagai zat dengan aktivitas biologis, karena sifat kimianya. Industri kosmetik, telah banyak menggunakan mineral tanah liat karena memiliki karakteristik yang menarik seperti mudah dalam aplikasi dan mudah dibersihkan, meminimalisir waktu pengeringan, dan tidak berbahaya secara dermatologis (Velasco et al., 2016). ...
... Masker wajah adalah produk kosmetik yang paling umum digunakan untuk peremajaan kulit (Nilforoushzadeh et al., 2018). Velasco et al. (2016) memaparkan penggunaan kaolin sebagai masker wajah. Kaolin yang dicampur dengan air dapat diaplikasikan langsung pada kulit pada suhu kamar. ...
... Untuk mengobati masalah kulit seperti komedo, flek hitam, dan jerawat, disarankan kaolin diaplikasikan menggunakan air panas. Suhu panas dapat meningkatkan sekresi keringat dan sebaceous, juga membuka lubang pilosebaceous dan mengaktifkan perubahan metabolisme dan ekskresi katabolit (Velasco et al., 2016). ...
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