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483
35
The science of nail polish, nail polish remover,
and nail moisturizers
SOMODYUTI CHANDRA AND ANUPAM DAS
With the advent of modern technologies and recent
advances in the eld of medical sciences, there is no ques-
tion of what is le unanswered, when it comes to clinical
or aesthetic point of view, nail care being no exception. In
this chapter, we have briey discussed the scientic ratio-
nale behind the use of nail moisturizers, nail polishes, and
nail polish removers, with a comprehensive overview of the
agents available in the market.
NAIL POLISH
Nail polish, also ca lled nail enamel or nail varnish, is a viscous
lacquer that is applied on the surface of nail plate of nger-
nails and toenails to form a water-resistant coating, primarily
for cosmetic enhancement. It is one of the most widely used
cosmetics throughout the world and it was estimated that in
2011, US consumers spent around 6.6 billion dollars only for
nail enhancement.1 e use of nail polishes can be t raced back
to 3000 B.C. when the Chinese and Egyptian women used
an “herbal-concoction” made of egg-white, gelatin, beeswax,
gum Arabic, and vegetable dyes (like henna or mashed rose)
to embellish their nails. Bright colors like red, black, and gold
were symbolic of power, superiority, and prosperity and were
generally reserved for the elite class, while the commoners
were allowed only pale shades.2
Michelle Menard is generally credited as the rst per-
son to conceptualize nail polish based on automobile paint,
and he later founded the cosmetic company Revlon in 1932.
Since then, nail polish formulations have evolved to provide
a platform for the variety of nail colors and eects desired
by the consumers.3
Although the main purpose of using nail enamel is
undoubtedly beautication and grooming, it is also used
for camouaging nail surface textural abnormalities
(like pitting, lines, ridges) and discolorations (yellow or
white). It is also used to temporarily strengthen thin and
brittle nails.4
e basic components include lm formi ng agents, resins,
plasticizers, solvents, and coloring agents as summarized in
Table 35.1. Nitrocellulose is the main lm-forming agent in
nail lacquer, which, along with resins like toluene sulphon-
amide formaldehyde, ensures adhesion of the nail paint to
the surface of the nail plate.5 is lm is oxygen-permeable,
which helps in maintaining the nail health while provid-
ing strength and gloss. Plasticizers like camphor, dibutyl
phthalate, or dioctyl phthalate provide exibility and adhe-
siveness to the lacquer by linking to polymer chains and
increasing the distance between them. Colorants (D&C Red
no. 6/7/19) and pearlizers (guanine, bismuth oxychloride,
titanium dioxide, ground mica) give the desired color and
shimmer. All these ingredients are dissolved or suspended
in a solvent, such as butyl acetate or ethyl acetate, which
evaporate to leave behind the colorful nish.6
Some polishes contain additional constituents like
thickening agents to make the polish easier to apply and
ultraviolet lters (benozophenone-1), which help prevent
discoloration when the polish is exposed to sunlight or
other forms of ultraviolet light. Some brands have added
natural oils like argan oil that acts as a nail-moisturizer and
makes damage less noticeable and perfumes to counteract
the unpleasant odor of the solvents.7
Nail polish application has been described in Box 35.1.
Nail polish is a relatively safe cosmetic with only 3% of the
users experiencing one or more untoward eects to it.10 e
most common side-eects include allergic contact dermatitis
(ACD) and nail-plate staining. e most commonly identi-
ed allergen is tosylamide formaldehyde resin (TSFR), which
is implicated in around 6.6% of the patch test-positive users.
Nail polish 483
Nail hardeners 485
Nail polish remover 485
Nail moisturizers 486
References 486
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484 The science of nail polish, nail polish remover, and nail moisturizers
Other allergens identied include formaldehyde, polyester
resin, dichloroethylene, amyl acetate, phthalates, guanine,
acrylate, sulfonamide, nitrocellulose, and shellac. Of late,
“hypoallergic nail polishes” have become popular and have
replaced TSFR with cellulose, acetate, butyrate, and polyes-
ter resin. Patch-testing is done to conrm ACD to nail polish
components, using the standard patch-test tray or by using the
patient’s own bottle of polish. Contact dermatitis can occur
locally, around the nail-unit or at a distant site, such as face,
eyelids, lips, and neck.11,12 Rarely, contact dermatitis in and
around genitals and perianal region,10 and desquamative gin-
givitis,13 have been reported. e common adverse eects and
their management have been summarized in Table 35.2.
In addition, certain pigments in the polish, particularly
when they are in a dissolved state rather than in suspension,
stain the nail-plate yellow. is mostly occurs with the deep
red polishes containing D&C Reds No. 6, 7, 34, or FD and C
yellow no. 5 Lake. e staining usually develops aer 7days
of wearing the polish, is more pronounced distally than prox-
imally, and fades spontaneously by about 14days; however,
can be removed by scraping the nail-plate with a scalpel.4
In instances when the nail polish is kept undisturbed for
several months, when a base coat is applied prior to the var-
nish or when the polish is reapplied without removing the
previous layers, it results in extreme dryness and crumbling
of the nail plate with whitish discoloration, mimicking
white supercial onychomycosis. is change was described
by Baran et al. as “keratin granulations” (Figure 35.1), and a
KOH mount can dierentiate it.14
Other reported adverse eects include onychodystrophy,
onycholysis, and paronychia. Sometimes nail varnish, used as a
barrier against nickel allergy, can itself lead to its sensitization.11
Uncommon but potentially serious adverse eect has been
reported with dibutyl phthalate (used as a plasticizer) including
decreased sperm mobility and viability15 and endocrine disrup-
tion leading to altered development of fetal testes.16
BOX 35.1: Nail polish application technique
The ideal nail polish application technique includes
the following steps8:
1. Base coat9: This is the rst layer, meant to
strengthen the nail plate. It is transparent with
high resin content, leading to stronger adherence
of nail polish to the nail. It also restores moisture
to the nail and helps in lling of ridges.
2. Nail polish: Pigmented nail polish applied as 2–3
coats.
3. Top coat: Again, a transparent coat that contains
more of nitrocellulose than resin. This prevents
nail polish chipping and fading and may contain
sunscreen. It adds shine to the polish.
4. Nail polish drier: Liquid that speeds up drying of
the nail polish by encouraging evaporation of the
solvent. Usually consists of vegetable oils, alco-
hols, and silicone derivatives.
Table 35.1 Constituents of a nail polish
Class of constituent Purpose Agents
Film-forming agent When the nail polish is applied the
solvent evaporates, leaving the
polymer to form a lm on the nail
Nitrocellulose, dissolved in a solvent, usually ethyl
acetate or butyl acetate
Plasticizers To make sure that nail polish stays
exible when it dries, making the nail
polish last longer and be less prone
to chipping
Dibutyl phthalate and camphor, trimethyl pentanyl
diisobutyrate, triphenyl phosphate, ethyl
tosylamide, glyceryl tribenzoate
Adhesive polymer resins To ensure that the nitrocellulose
adheres to the nail plate’s surface
Tosylamide-formaldehyde resin
a polyester resin or cellulose acetate butyrate in
hypoallergenic nail polishes
Dyes and pigments To impart color Chromium oxide greens, chromium hydroxide, ferric
ferrocyanide, stannic oxide, titanium dioxide, iron
oxide, carmine, ultramarine, and manganese violet
Opalescent pigments To add glittery/shimmer look Mica, bismuth oxychloride, natural pearls, and
aluminum powder
Thickening agents To maintain the sparkling particles in
suspension while in the bottle
Stearalkonium hectorite
Ultraviolet stabilizers Resist color changes when the dry lm
is exposed to sunlight
Benzophenone-1
AQ 1
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Nail polish remover 485
Nail hardeners17
ese are modied nail polish and are applied as a base coat
for the purpose of strengthening the nail plate. is base
coat moves through porous structure of nail plate, decreas-
ing loss of water through nail plate signicantly and hence
providing strength and exibility to the nail plate. ese
nail hardeners are used in cases where nails are so, brittle,
or prone to splitting.
ey may contain titanium-silicone-zirconium polymers,
polytef, nylon, calcium, and biotin. Addition of keratin, vita-
mins, calcium uoride, natural oils, nylon bers, Teon, and
silk can be done. Prolonged usage can lead to brittle nails
(cross-link density rises and exibility is reduced). e
patient should be advised to periodically remove nail hard-
eners with nail polish remover. Other adverse eects include
contact allergic dermatitis, onycholysis, and subungual
hyperkeratosis.
NAIL POLISH REMOVER
Nothing in the world is constant, including the nail paints
that change with a person’s clothes and moods. Nail polish
removers are organic solvents that break down and dissolve
the polish, thus removing it from the nail plate.
An ideal lacquer remover should not be volatile enough
to evaporate during application, should neither have strong
degreasing eect nor leave the nails sticky, and should be
non-irritating to surrounding skin.
e solvents used in nail enamel removers include
acetone; gamma butyrolactone; and amyl, butyl, or ethyl
acetate, which are mixed with fatty materials such as cetyl
alcohol, lanolin, castor oil, or other synthetic oils.
e acetone in the remover is harsh on the nails and peri-
ungual skin and is the commonest cause of irritant contact
dermatitis. Excessive use of these products can also lead to
dry, brittle nails. A less harsh remover contains ethyl acetate
along with isopropyl alcohol. Acetonitrile, a component of
the remover, has been banned in the European countries
since 2000, because of its toxic and carcinogenic potential.
“Acetone-free nail polish removers” are now widely avail-
able and are generally considered safe. JJ Brown et al., how-
ever, highlighted the dangers of these “safe” acetone-free
removers that contain gamma butyrolactone, which is rapidly
metabolized to gamma hydroxybutyrate on ingestion, result-
ing in systemic toxicity. ey reported a case where accidental
suction of polish removing pads led to bilateral pneumothora-
ces, pneumomediastinum, upper respiratory obstruction, and
nally cardiorespiratory collapse and coma.18 is gamma
butyrolactone has also been reported to cause fatal and non-
fatal intoxication,19 acute toxicity in 9-to-15-month olds,20
withdrawal delirium with acute renal failure,21 and rapid
onset of coma, respiratory depression, and bradycardia.22
Another potentially serious adverse eect caused by acci-
dental ingestion of nail polish removers is methemoglobin-
emia. Acetone, N, N-dimethyl-p-toluidine, and nitroethane
are the responsible causal agents.23
Table 35.2 The common adverse effects and management
Adverse reaction Explanation/mechanism Precaution and management
Brittle nails Dehydration due to solvent
exposure, used in removing nail
polish, gel nails
Avoid harsh chemicals. Do not use nail polish remover
frequently
Allergic contact dermatitis Acrylates, formaldehyde, TSFR in
nail polish
Use hypoallergenic formaldehyde-free nail polish
Onycholysis excessive use of nail cosmetics Rest to nails every 3months
Yellow staining Scraping with scalpel
Keratin granulations Dehydration of nail plate, leading of
clumping of keratin proteins
Several-week-long break from nail polish, nail polish
remover and chemicals in conjunction with using
moisturizers and/or hand creams to replenish the
moisture balance of the nail
Figure 35.1 Keratin granulations. (Courtesy of Prof.
Archana Singal.)
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486 The science of nail polish, nail polish remover, and nail moisturizers
Open-patch testing, at a concentration of 10% in olive
oil, is recommended for detection of adverse eects to
nail polish removers due to their high volatile solvent
concentrations.7
NAIL MOISTURIZERS
e nail is a richly keratinized tissue with a high con-
tent of cysteine, a sulfur-containing amino acid. 10% of
the dry weight of nail is constituted by sulfur and these
hard keratins attribute to the toughness of the nail and
the superlative barrier function. e content of lipids and
water in the nails is low, as compared to stratum cor-
neum. But this is to be noted that nail is highly perme-
able to water. When the water content of nail increases, it
becomes so and opaque. However, when the water con-
tent decreases, it becomes dry and brittle. So, proper and
adequate moisturization of nails is essential to prevent
them from becoming brittle.24
Moisturizing nails help to maintain them healthy and
glistening. Patients must be advised to refrain from fre-
quent use of hand sanitizers, harsh soaps and cleansers,
formaldehyde-containing products, and acetone to prevent
dehydration of the nail plate. Frequent soaking in water
must be avoided, as this may result in brittle nails.
Urea (5%–20%) and lactic acid (5%–10%) are found to be
highly ecacious in hydrating the nails. ey increase the
water-holding capacity of the nails by digesting the nail ker-
atins and opening the water-binding sites. e disadvantage
is that the eects are short-lived and this mandates frequent
re-application for sustained eects.25
Other moisturizing agents found to be useful include
glycerin, petrolatum, beeswax, mineral oils, natural oils
(almond, avocado, jojoba, and sunower), waxes (cetyl alco-
hol, stearyl alcohol, and beeswax), and humectants (aloe
vera, ceramides, and glycerin).
us, moisturizers constitute an important part of nail
care and we should be well-acquainted with the options
available, in order to provide eective management to the
patients.
REFERENCES
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Dermatol Ther 2012;25:481– 490.
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2000;18:675–683.
4. Rich P. Nail cosmetics. Dermatol Clin
2006;24:393–399.
5. Schlossman ML. Nail-enamel resins. Cosmetic
Technol 1979;1:5 3.
6. Draelos ZD. Cosmetic treatment of nails. Clin
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9. Baran R. Nail cosmetics: Allergies and irritations. Am
J Clin Dermatol 2002;3(8):547–555.
10. Dahdah MJ, Scher RK. Nail diseases related to nail
cosmetics. Dermatol Clin 2006;24:233–239.
11. Lazzarini R, Hafner M de FS, Lopes AS de A,
Oliari CB. Allergy to hypoallergenic nail polish:
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2017;92:421–422.
12. Lazzarini R, Duarte I, de Farias DC, Santos CA,
Tsai AI. Frequency and main sites of allergic con-
tact dermatitis caused by nail varnish. Dermatitis
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13. Staines KS, Felix DH, Forsyth A. Desquamative gingi-
vitis, sole manifestation of tosylamide/formaldehyde
resin allergy. Contact Dermatitis 1998;39:90.
14. Brauer E, Baran R. Cosmetics: The care and
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Management, 3rd ed. Oxford, UK: Blackwell; 2001:
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15. Pant N, Pant A, Shukla M, Mathur N, Gupta Y,
Saxena D. Environmental and experimental exposure
of phthalate esters: The toxicological consequence
on human sperm. Hum Exp Toxicol 2011;30:507–514.
16. Lorizzo M, Piraccini BM, Tosti A. Nail cosmetics in
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17. Habert R, Muczynski V, Lehraiki A, Lambrot R,
Lécureuil C, Levacher C et al. Adverse effects of
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18. Brown JJ, Nanayakkara CS. Acetone-free nail pol-
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2005;43:297–299.
19. Lenz D, Rothschild MA, Kröner L. Intoxications due
to ingestion of gamma-butyrolactone: Organ distri-
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butyrolactone. Ther Drug Monit 2008;3 0 :755 –761.
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21. Bhattacharya IS, Watson F, Bruce M. A case of
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1997;39:234–235.
23. Patra S, Sikka G, Khaowas AK, Kumar V.
Successful intervention in a child with toxic
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soning. Indian J Occup Environ Med 2011;15:137–138.
24. Andre J, Scheers C, Baran R. Normal nail and use
of nail cosmetics and treatments. In: Barel AO, Paye
M, Maibach HI, Eds. Handbook of Cosmetic Science
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Author Query Sheet
Chapter No.: 35
Query No. Query Response
AQ 1 Please provide footnote indicator details (a) for Table 35.1
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