Contact dermatitis to methylisothiazolinone

Abstract

Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact dermatitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000 ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized.

Full text

912 CommunICatIon
Contact dermatitis to methylisothiazolinone*
Maria Antonieta Rios Scherrer1 Vanessa Barreto Rocha1
Ana Regina Coelho Andrade1
DOI: http://dx.doi.org/10.1590/abd1806-4841.20153992
Abstract: Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact der-
matitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has
shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000
ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and
our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized.
Keywords: Additives in cosmetics; Dermatitis, allergic contact; Preservatives, pharmaceutical
s
Received on 01.09.2014
Approved by the Advisory Board and accepted for publication on 19.09.2014
* Study conducted at a Private practice and at the Hospital das Clínicas of Universidade Federal de Minas Gerais (HC-UFMG) – Belo Horizonte (MG), Brazil.
Financial Support: None.
Conict of Interest: None.
1 Universidade Federal de Minas Gerais (UFMG) – Belo Horizonte (MG), Brazil.
©2015 by Anais Brasileiros de Dermatologia
Methylchloroisothiazolinone and methyliso-
thiazolinone (MCI/MI), also known as Kathon CG or
Euxyl K 100, has been used (in a xed 3:1 mixture) as
a preservative since the 70s. In 2000, MI started being
commercialized alone for use in industrial products
such as paints and adhesives, and since 2005 it has
also been used in cosmetic products at concentrations
ranging from 50 to 100ppm. Due to this extensive use,
the number of allergy cases caused by MCI/MI or by
MI alone has been increasing.1-5
Some examples of cosmetic products that con-
tain MI are: products for children and babies, bath
products, makeup (eyeliners, makeup removers,
blush and face powder), hair care products (such as
dyes and bleaches), nail and waxing products, mois-
turizing creams, sunscreen and baby wipes. Accord-
ing to the Food and Drug Administration, in 2010,
about 2408 American cosmetic products used MI as a
preservative.
Examples of occupational products that contain
MI are: paints, glues, lacquers, cutting oils and other
products for industrial use. So far there are neither
rules establishing the maximum concentration al-
lowed for use in nished products, nor a mandatory
requirement to specify the MI content on product la-
bels, which makes it difcult to identify this compo-
nent in occupational products.
With regard to household cleaning products that
contain MI, we may cite: dishwasher soaps, washing
powders, laundry detergents, stain removers, fabric
softeners, glass cleaners, products for wood protection
and even the so-called “green” cleaning products..3
Although the epicutaneous testing with MCI/
MI can only detect contact allergy to MI alone, about
40% of cases fail to be diagnosed, possibly due to its
low concentration in this combination.1,2,3,4,5
An Bras Dermatol. 2015;90(6):912-4.

Contact dermatitis to methylisothiazolinone.. 913
Currently,MCI/MIis testedin Europeand in
theUSAin concentrationsof0.01%inaqueous solu-
tion(100ppm)and,inBrazil,inconcentrationsof0.5%
in petrolatum. 5
Recent studies recommend MI concentrations
of 2000 ppm in aqueous solution since at this con-
centration,moreallergycasesaredetected.Moreover
thereareno reports ofsensitization by patchtesting
and chemical investigations have shown that MI is
evenlydistributedinaqueoussolution,butnotinpet-
rolatum.1,2,3
MIsensitivepatientsalsoreacttoMCI,although
the contrary is not necessarily true. 4,5
MIisnottested inEuropean,NorthAmerican
andBrazilianstandard trays, whichlimitsthe possi-
bilityofmakingthediagnosisofMIallergies.Recent
articles recommend its inclusion in European and
NorthAmericantrays.4
We studied a series of 23 patients tested between
MarchandJuly2014withtheBrazilianstandardtray,
which contains MCI/MI (FDA Allergenic) adding
MI0.2%in aqueoussolution(Chemotechnique)toit.
The tests were carried out by using the Finn Chamber
patchtesttechnique(EpitestLtdOr,Tuusula,Finland)
onScanportape(ASNorgeplasterAlpharma,Vennes-
la,Norway).Readingsweretakenat48and96hours,
followingtheinternationalreadingstandard.Allergic
reactionsweregraded as+,++ or+++ basedonthe
intensity of positive reactions, which manifested as
erythematouspapules,vesiclesand disseminationof
thereactionwithcrustingandulceration,respectively.
Thecosmetictray(FDAAllergenic)andothercomple-
mentary allergens were included in the investigation
ofsomepatients(whenrelevant).
The mean age of all 23 patients was 48.43 years
(standard deviation of 14.95 years). 21 (91.30%) pa-
tientswerewomen.14subjects(61%)showedaneg-
ative reaction to MCI/MI and MI; 8 subjects (35%)
showed a positive reaction to MCI/MI and MI; and
onlyonesubject(4%)showedapositivereactiontoMI
and a negative reaction to MCI/MI.
Amongthose patientswho showeda positive
reactionto MI,90% haddisseminated lesions,being
90%onthelegs,60%onthetrunkandabdomen,50%
onthe handsand scalp,and 40%on theface. These
dataareconsistentwithapreviousstudyonMCI/MI,
exceptforthehigherfrequencyoflesionsontheface
found in the current study. 5
Among the aforementioned cases, we high-
light the one that was positive for MI and negative
forMCI/MI.A27-year-oldcaucasian femaleteacher
was referred for patch testing due to a 2-year-old his-
toryofitchyandrecurrentrashonthelegs,abdomen,
trunkandface(Figures1 and 2). Shehad a previous
history of bronchitis. The patient was tested with the
standardand thecosmeticstrays,addingthefollow-
ing allergens: DMDM hydantoin, fragrance mix 2,
phenoxyethanol, ethylene-urea-melamine formalde-
hyderesin,disperseblue mix andmethylisothiazoli-
none 0.2% in aqueous solution (Chemotechnique).
Theresultswere+forMIafter 48 and 96 hours.The
test was considered relevant due to the presence of
thisallergeninseveralproductsusedbythepatient,
suchasshampoos,hairconditionersandmoisturizing
creams.Thefrequentuseoftheseproductsexplained
the appearance of disseminated lesions and for so long
a time. The lesions regressed after treating the patient
withtopicalsteroids(betamethasone)andinstructing
her to use alternative products without the causative
agent.
In the case reported above, the patient had a
widespread rash with prolonged course, which im-
pared her quality of life. The correct diagnosis led
hercure,andwasonlypossiblebecauseofthepatch
testingwith MI,since thetesting with MCI/MI was
negative.
An Bras Dermatol. 2015;90(6):912-4.
Figure 1:
Erythema-
tous,papular,
malarplaque
Figure 2: Erythematous-brownish,scalyplaquesontheabdomen

914 Scherrrer MAR, Rocha VB, Andrade ARC
MI is an important emerging allergen whose
sensitizationfrequencyisrising.
Increasedsensitization to MCI/MIin Brazilis
areality,but,unfortunately,thismixturedoes notal-
lowthedetectionofallcasesofallergytoMI,asseen
before. Sensitization to MI should be considered in
patients with suspected allergy to cosmetics and/
orsunscreens,rashon thefaceand/ordisseminated
throughoutthebody,asillustratedabove.1-5
WesuggesttheinclusionofMIinaqueoussolu-
tionintotheBrazilianstandardtray,atleasttemporar-
ily,untilinternationalandnationalnormsregulateits
use.q
How to cite this article: ScherrrerMAR,RochaVB,AndradeARC.Contactdermatitistomethylisothiazolinone.
AnBrasDermatol.2015;90(6):912-4.
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Mailing address:
Maria Antonieta Rios Scherrer
Rua Rio Grande do Norte, 726 - Sala 804.
30130-130 - Belo Horizonte - MG
Brazil
E-mail: vanessabarreto@oi.com.br
An Bras Dermatol. 2015;90(6):912-4.