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Amended Safety Assessment of Methylisothiazolinone
as Used in Cosmetics
Status: Final Amended Report
Release Date: October 8, 2014
Panel Meeting Date: September 8-9, 2014
The 2014 Cosmetic Ingredient Review Expert Panel members are: Chairman, Wilma F. Bergfeld, M.D., F.A.C.P.;
Donald V. Belsito, M.D.; Ronald A. Hill, Ph.D.; Curtis D. Klaassen, Ph.D.; Daniel C. Liebler, Ph.D.; James G.
Marks, Jr., M.D.; Ronald C. Shank, Ph.D.; Thomas J. Slaga, Ph.D.; and Paul W. Snyder, D.V.M., Ph.D. The CIR
Director is Lillian J. Gill, DPA. This safety assessment was prepared by Christina L. Burnett, Senior Scientific
Analyst/Writer, and Ivan J. Boyer, Ph.D., Senior Toxicologist.
© Cosmetic Ingredient Review
1620 L St NW, Suite 1200 ◊ Washington, DC 20036-4702 ◊ ph 202.331.0651 ◊fax 202.331.0088
◊ cirinfo@cir-safety.org
ABSTRACT
The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) reviewed the safety of methylisothiazolinone (MI),
which functions as a preservative. The Panel reviewed relevant animal and human data provided in this safety
assessment, and concluded that MI is safe for use in rinse-off cosmetic products at concentrations up to 100 ppm and
safe in leave-on cosmetic products when they are formulated to be non-sensitizing, which may be determined based
on a quantitative risk assessment (QRA).
INTRODUCTION
In 2010, the Panel published a final report of the safety assessment of methylisothiazolinone (MI) with the
conclusion that “MI is safe for use in cosmetic formulations at concentrations up to 100 ppm (0.01%).”1 At the
March 2013 CIR Expert Panel meeting, the Panel reviewed newly provided clinical data indicating a higher than
expected frequency of individuals who have allergic reactions to the preservative MI. In some cases, comparative
data were available indicating a higher frequency of positive reactions than currently seen with the combination
preservative, methylchloroisothiazolinone/methylisothiazolinone (MCI/MI). The Panel reopened this safety
assessment to gather and evaluate additional data.
In June 2014, the Panel reviewed the results of QRAs performed by Cosmetics Europe and the CIR
Science and Support Committee (CIR SSC). The results supported the safety of the use of MI in rinse-off product
categories at concentrations up to 100 ppm. However, the QRAs indicated that MI use in many leave-on product
categories would be safe only at lower concentrations. The Panel issued a tentative amended safety assessment for
public comment with the conclusion that MI is safe for use in rinse-off cosmetic products at concentrations up to
100 ppm and safe in leave-on cosmetic products when they are formulated to be non-sensitizing, which may be
determined based on a QRA.
The Panel previously reviewed the safety of the mixture MCI/MI (sold at a ratio of 3:1; trade names
include Kathon microbiocides) with the conclusion that the mixture “may be safely used in ‘rinse-off’ products at
a concentration not to exceed 15 ppm, and in ‘leave-on’ products at a concentration not to exceed 7.5 ppm”.2
Data from the original MI safety assessment report, which was finalized in 2008 and published in 2010, are
summarized in italics in each appropriate section of this report.
CHEMISTRY
The definition, physical and chemical properties, method of manufacturing, and impurities of MI were
described in the original safety assessment.1
Figure 1. Methylisothiazolinone
USE
Cosmetic
Table 1 presents the historical and current product formulation data for MI. MI functions as a preservative
in cosmetic products.3 According to information from the Food and Drug Administration (FDA) Voluntary
Cosmetic Registration Program (VCRP) database in 2007, MI had 1125 reported uses, with the majority of the uses
reported in non-coloring hair conditioners and shampoos.1 It should be noted that the information from the VCRP in
2007 did not clearly distinguish cosmetic products in which MI was used in combination with MCI from products in
which MI was used without MCI. This safety assessment addresses the use of MI in cosmetic products that do not
also contain MCI. In 2008, industry reported the maximum use concentration range to be 4 x 10-6% to 0.01%, with
0.01% reported in both leave-on and rinse-off baby, non-coloring hair, and dermal contact products.1 In 2014, the
VCRP database indicated that MI is used as an ingredient in 745 cosmetic products that do not also contain MCI,
with the majority of the uses reported in leave-on products such as skin moisturizers.4 A survey of use
concentrations conducted by the Personal Care Products Council (Council) in 2014 reported a maximum
concentration of use range of 3.5 x 10-8% to 0.01%, with 0.01% reported in multiple product categories including
eye makeup remover, hair shampoos and conditioners, and skin care products (both leave-on and rinse-off).5
MI was reported to be used in non-coloring hair sprays and hair tonics or dressings that may be aerosolized
or become airborne and could possibly be inhaled. In practice, 95% to 99% of the droplets/particles released from
cosmetic sprays have aerodynamic equivalent diameters >10 µm, with propellant sprays yielding a greater fraction
of droplets/particles below 10 µm compared with pump sprays.6-9 Therefore, most droplets/particles incidentally
inhaled from cosmetic sprays would be deposited in the nasopharyngeal and bronchial regions and would not be
respirable (i.e., they would not enter the lungs) to any appreciable amount.7,8
The European Union’s Scientific Committee on Consumer Safety (SCCS) recently released an updated
opinion on the use of MI.10 It states that, in leave-on cosmetic products (including “wet wipes”), no safe
concentration has been adequately demonstrated for induction or elicitation of contact allergy. In rinse-off cosmetic
products, the SCCS has recommended that concentrations up to 0.0015% (15 ppm) MI are safe, in terms of the
potential for induction of contact allergy, but stated that there is no information available to evaluate the potential for
this ingredient to elicit contact allergy. Furthermore, the SCCS opinion states that MI should not be added to
cosmetic products that contain MCI/MI.
Cosmetics Europe, the personal care products industry trade association in Europe, has recommended the
discontinuation of MI specifically in leave-on skin products, including wet wipes.11
Non-Cosmetic
The non-cosmetic uses of MI include use in water-based paints, which has been noted in a number of case
studies of sensitization reactions (e.g., see Table 3). The uses of MI in paints and other non-cosmetic products were
described in the original safety assessment.1
TOXICOKINETICS
Absorption, Distribution, Metabolism, and Excretion
The percutaneous absorption of radiolabeled MI (99.88% radiochemical purity) was determined using rat
skin mounted on diffusion cells. Over a 24-hour period, the rate of absorption was 0.0059, 0.0277, and 0.0841 μg
equivalents/cm2/h for 25, 75, and 150 ppm dose groups, respectively, and the mean amount of total applied
radioactivity absorbed was 21.4%, 33.7%, and 51.2% for 25, 75, and 150 ppm dose groups, respectively. The total
dose absorbed of aqueous solutions containing radiolabeled MI (96.90% radiochemical purity) in human epidermis
was 29.8%, 38.0%, and 54.7% for 52.2, 104.3, and 313 μg MI/ml dose groups. The rate of absorption was 0.037
μg/cm2/h over a 24-hour exposure. In the same study, the total dose absorbed from shampoo, body lotion, and facial
cream formulations containing 100 μg MI/ml was 29.5%, 8.98%, and 19.6%, respectively. The rates for absorption
of MI in the formulations over a 24-hour exposure ranged from 0.007 to 0.026 μg/cm2/h. After oral dosing of 100
mg/kg radiolabeled MI (96.70% radio purity) in mice, total radioactive residues (TRR) were highest in the liver and
lowest in the bone 1 h post-dosing. At 24 h post-dosing, TRR declined significantly in all tissues and the tissue-to-
plasma ratio showed that the radiolabel partitioned preferentially from plasma to tissues. Blood had the highest
tissue-to-plasma ratio at 48 h. TRR was higher in male tissues than female tissues overall. Most radiolabeled
metabolites of MI (99.08% radio purity) were excreted in urine and feces by rats within 24 h of oral dosing. Tissue
sampling at 96 h post-dosing found 1.9-3.6% of the radiolabel, mainly in blood. Total mean recovery of the
radiolabel was 92-96%. Major metabolites in urine were N-methyl malonamic acid (NMMA), 3-mercapturic acid
conjugate of 3-thiomethyl-N-methyl-propionamide, and N-methyl-3-hydroxyl-propamide. Another metabolism study
of radiolabeled MI (96.90% radio purity) conducted on bile duct-cannulated rats had an 88% recovery of the dose
at 24 h post oral dosing. The majority of the radiolabel was found in bile, urine, and feces. No intact MI was
recovered and the main metabolites were NMMA and 3-mercapturic acid conjugate of 3-thiomethyl-N-methyl-
propionamide.
TOXICOLOGICAL STUDIES
Acute Toxicity
In acute oral toxicity studies, MI was slightly toxic in rats in concentrations ranging from 9.69% to 99.7%.
At 9.69%, the LD50 for male and female rats was 274.6 and 105.7 mg/kg body weight, respectively. Rats that died
during these studies had reddened intestines and/or stomach mucosa, clear or red/yellow fluid in the intestines
and/or stomach; blackened intestines and distended stomachs. Studies on body lotion, shampoo, and sunscreen
formulations in rats containing 100 ppm MI found no treatment related effects and an LD50 greater than 2000 mg
formulation/kg body weight. Slight toxicity, including gastrointestinal changes, was observed in mice that orally
received 97.5% MI. The LD50 was 167 mg/kg body weight. An acute oral toxicity study of the metabolite NMMA
found the substance slightly toxic. The calculated oral LD50 for NMMA in males and females was 3550 and 4100
mg/kg body weight, respectively. MI at 97.5% was slightly toxic in rats in an acute dermal toxicity study. The
substance was corrosive to the skin. The LD50 was calculated to be 242 mg/kg body weight. In another acute
dermal toxicity study, 9.69% MI was corrosive to rat skin, but no deaths occurred during the study. The LD50 was
greater than 484.5 mg/kg body weight. Acute inhalation toxicity studies in rats found that 53.52% and 97.8% MI
were slightly toxic after 4 h exposures. The LC50 were 0.35 and 0.11 mg/L. Rats that died during these studies had
reddened lungs and distended gastrointestinal tracts. Mice exposed to 10 minutes of atomized 98.6% MI had up to
47% decrease in respiratory rates that equated to moderate responses for sensory irritation.
Repeated Dose Toxicity
No toxic effects were observed when 97.5% MI was administered to rats in drinking water for 13 weeks at
concentrations of 0, 75, 250, or 1000 ppm. Dogs that were fed diets prepared with 51.4% MI for 3 months had a
NOAEL of 1500 ppm. In a subchronic study, rats fed the metabolites NMMA [and malonic acid (MA), up to 220
ppm and 44 ppm in the diet, respectively]* for 3 months had no effects observed in body weight, food consumption,
hematology, clinical chemistry, urinalysis, ophthalmology, or gross pathologic changes. Beagle dogs that received
these metabolites [up to 500 ppm NMMA and 100 ppm MA]* in their diets for 3 months had no systemic toxicity.
*Bracketed text presents corrections to the original report
REPRODUCTIVE AND DEVELOPMENTAL TOXICITY
In a teratogenicity study, MI was administered by daily single oral doses to pregnant rats at doses of 5, 20,
or 60 (reduced to 40) mg/kg body weight/day on gestation days 6-19. Females in the high dose group had clinical
signs of rales, gasping, and labored breathing and at necropsy had red areas in the glandular portion of the
stomach and lungs. No treatment-related effects were observed in the fetuses. The maternal and developmental
NOAEL were 20 mg/kg/day and 40 mg/kg/day, respectively. In a teratogenicity study of MI in rabbits, pregnant
females received daily single oral doses of 3, 10, or 30 mg/kg/day MI on gestation days 6-28. Maternal effects in
the 30 mg/kg/day group included decreased defecation and dark red areas in the stomach. The maternal NOAEL
was 10 mg/kg/day. No treatment-related effects were observed in the fetuses and the developmental NOAEL was
determined to be 30 mg/kg/day. A two-generation reproduction toxicity test found that MI in drinking water at
concentrations up to 1000 ppm was not a reproductive toxicant.
CARCINOGENICITY
Studies of the carcinogenicity of the sole ingredient MI were not available; however, a 2 year drinking
water study in rats concluded that the mixture MCI/MI tested up to 300 ppm was not a carcinogen.
GENOTOXICITY
MI (up to 1000 µg/plate) and the metabolite NMMA (up to 5000 µg/plate) were not mutagenic in the Ames
test when tested with and without metabolic activation. In a Chinese hamster ovary cell assay, 97.5% pure MI was
non-mutagenic when tested with and without metabolic activation (0.5 - 40.0 μg/ml). However, another CHO assay
that studied MI at 97.5% a.i. (0.0785 - 5000 μg/ml) found significant increases in cells with chromosome
aberrations, with and without metabolic activation. The aberrations were accompanied by significant cytotoxicity,
which may have caused a false positive in this assay. MI was non-mutagenic in an unscheduled DNA synthesis
assay and in a micronucleus test.
NEUROTOXICITY
An acute in vitro neurotoxicity study of MI (up to 300 µM) in embryonic rat cortical neurons and glia
observed widespread neuronal cell death within 24 h in the cortical cultures. Gliotoxicity was low. A 14-hour in
vitro neurotoxicity study of MI (up to 3.0 µM) from the same laboratory concluded that prolonged exposure to MI
and related isothiazolones may damage developing nervous systems. However, no evidence of neurotoxicity has
been observed in vivo.
IRRITATION AND SENSITIZATION
Irritation
Non-Human
A bovine cornea study classified MI [neat] as mildly irritating. Ocular irritation studies in body lotion,
shampoo, and sunscreen formulations containing 100 ppm MI found the formulations non-irritating in rabbit eyes.
Undiluted 97.8% MI was corrosive to intact rabbit skin after an exposure period of 1 h. Rabbit dermal irritation
studies of MI at 9.69% and 10% concluded the chemical was non-irritating. In EpiDerm skin constructs, 1.7% MI
applied for 3 or 60 minutes were non-corrosive. In the same study, 51.5% MI was non-corrosive in the 3 minute
exposure but corrosive at the 60 minute exposure.
Human A single 24-hour application of 100 ppm MI in 40 volunteer subjects did not produce skin irritation.
Respective skin irritation studies in body lotion, shampoo, and sunscreen formulations containing 100 ppm MI also
found MI to be nonirritating.
Sensitization
Non-Human
In a guinea pig maximization test, 0.076% w/v MI was a weak sensitizer and a follow-up study found that
0.015% MI produced no sensitization. An investigation using the Buehler method found that 99.8% MI was a
sensitizer at concentrations > 1000 ppm. Another maximization test that evaluated the sensitization potential of
99.7% MI concluded that the chemical was not a sensitizer at concentrations up to 800 ppm. MI was a sensitizer at
concentrations > 1.5% in an open epicutaneous test. Results from one local lymph node assay (LLNA) indicated
that 99.8% MI produced sensitization at >10,000 ppm. In one local lymph node assay (LLNA), the EC3 for MI was
calculated to be 25,150 ppm. In another LLNA, the calculated EC3 was 0.86% (8600 ppm). In a study using both the
LLNA and cytokine profiling to assess MI, the EC3 for MI diluted in acetone/olive oil was 0.4% (4,000 ppm), and it
was 2.2% (22,000 ppm) when diluted in propylene glycol (a moderate skin allergen); however the cytokine profile of
0.5% MI in acetone/olive oil was not typical for respiratory allergens and the authors concluded that MI was not
likely to cause sensitization of the respiratory tract. The metabolite NMMA did not induce hypersensitivity in a
local lymph node assay up to and including 30% concentration.
A letter to the editor reporting the re-evaluation of published LLNA data indicated that MI should be
categorized as a strong sensitizer and not a moderate sensitizer, in contrast to previous reports.12 The earlier reports
incorrectly reported 1.9% as the EC3 for MI; the correct value is 0.4%, which is the lowest EC3 estimated from
multiple LLNAs using, for example, an acetone/oil vehicle.
Human In a clinical study of 22 patients tested with fractions isolated from Kathon CG that included MI and MCI,
only 2 patients had positive reactions to MI. Sensitization may have been due to cross-reactions to MCI. MI was
determined to be a weak sensitizer in a study of 12 patients. In a cumulative irritation/sensitization study of MI in
80 subjects, the sensitization threshold was determined to be at or around 1000 ppm. Eighty-five patients with pre-
determined sensitization to MI/MCI were tested epicutaneously to 500 or 1000 ppm MI. The results show that at
high concentrations of MI (500 to 1000 ppm), 32% of the subjects with known sensitivity to MCI/MI reacted to MI.
A human RIPT in 98 subjects tested with 100 ppm MI concluded that MI did not induce skin sensitization in humans.
A series of RIPT evaluating the sensitization of 50% MI at concentrations of 200, 300, 400, 500, or 600 ppm
concluded that MI up to 600 ppm was not a dermal sensitizer.
MI was named the Allergen of the Year for 2013 by the American Contact Dermatitis Society because of
the increasing frequency of use of this preservative in consumer products and the increasing incidences of contact
allergy reported to be associated with exposures to MI, especially in the European Union.13-16 The standard series of
patch testing includes exposures to 100 ppm MCI/MI mixture (3:1 ratio). This test may miss up to 40% of subjects
with contact allergy to MI, alone, because of the relatively low MI concentration in the MCI/MI mixture tested
(approximately 25 ppm MI in a 100 ppm MCI/MI test solution).17,18 Recommendations have been made to test for
contact allergy to MI alone, although there currently is no consensus about the concentration of MI that should be
used in such testing.13,19-24
The dose-response relationship of contact allergy to MI was investigated in 11 MI-allergic patients.25 The
patients were patch tested with 2 dilution series of 12 doses of MI (Neolone 950™ 9.7% active ingredient) in 10%
ethanol and 90% aqua and 12 doses of MI with 9.26 µg phenoxyethanol/cm2 in 10% ethanol and 90% aqua.
(Phenoxyethanol may increase antimicrobial efficacy of MI and was tested to determine if it influenced reactivity to
MI). The MI doses with and without phenoxyethanol were 0.0105, 0.105, 0.147, 0.21, 0.441, 1.47, 2.94, 4.41, 8.82,
15, 30, and 60 μg MI/cm2. Controls (n=14) who were not MI-allergic patients were patch tested with 60 µg MI/cm2
and 9.26 µg phenoxyethanol/cm2. Each test site received 15 µl of each dilution applied by filter disc in a Finn
Chamber and were occluded for 2 days. Readings were performed on days 2, 3 or 4, and 7. The subjects also
underwent a repeated open application test (ROAT) with a cream that contained 0, 0.0105, 0.105, or 0.21 µg MI/cm2
(0, 5, 50, or 100 ppm MI) with phenoxyethanol in 10% ethanol and 90% water. The patients applied 20 µl of the
test solution from 4 different bottles twice a day to four 3 cm2 areas of the volar forearm. Sites were read on days 2,
3 or 4, 7, 14, and 21, with additional reading if a reaction occurred between visits. In the patch test, results showed
that phenoxyethanol had no influence on reactions to MI. The lowest eliciting dose in the patch test was 1.47 µg
MI/cm2 (49 ppm). No reactions were observed at 0.441 µg MI/cm2 (15 ppm) or lower, nor were there any reactions
in the control subjects. In the ROAT, 7 patients (64%) reacted to 0.105 and 0.21 µg MI/cm2 and 2 patients (18%)
reacted to 0.0105 µg MI/cm2. The authors of this study recommended that the permitted amount of MI in cosmetics
be reduced from 100 ppm.
In a HRIPT of 226 subjects performed in accordance with the International Contact Dermatitis Research
Group (ICDRG) criteria for MI, 56 subjects received 100 ppm MI alone and the remaining 170 subjects received
100 ppm MI in combination with various glycols that are used as preservative boosters.26 No evidence of induced
allergic contact dermatitis was observed in any of the subjects, with or without glycols. The study concluded that
100 ppm MI does not cause a risk in cosmetic products when applied on uncompromised skin in the general
population.
QUANTITATIVE RISK ASSESSMENT
Both Cosmetics Europe and the CIR SSC conducted QRAs, assuming 100 ppm (0.01%) MI in many
categories of cosmetic products, in response to the increased incidences of contact sensitization to MI in Europe.27,28
Both of these QRAs were conducted using the same no expected sensitization induction level (NESIL = 15
µg/cm2/day) and sensitization assessment factors (SAFs).
Table 2 summarizes the QRA conducted by the CIR SSC. A conservative NESIL of 15 µg/cm2/day was
derived for MI based on a weight-of-evidence (WoE) evaluation of data from 5 HRIPTs and 4 LLNAs. The NESIL
was then used to calculate acceptable exposure levels (AELs) for the potential for the induction of sensitization from
dermal exposure to MI in cosmetic products, assuming the maximal use concentration of 100 ppm MI and product-
category-specific SAFs. The ratio of the AEL and the consumer exposure level (CEL) was then calculated for each
of many cosmetic product categories, ranging from hair conditioners (CEL = 0.02 µg/cm2/day) to lipsticks (CEL =
1.15 µg/cm2/day). The concentration of an ingredient is considered to be acceptable in a product when AEL/CEL ≥
1 (i.e., AEL ≥ CEL).
According to the Cosmetics Europe calculations the lowest estimated CEL to MI was 0.0011µg/cm2/day for
shower gel, and the highest estimated exposure was 2.27 µg/cm2/day for a nail varnish. The AEL/CEL ratios
indicated that concentrations of MI up to 100 ppm (0.01%) would be acceptable for 20 of the 42 categories assessed
by Cosmetics Europe and for 27 of the 60 categories assessed by the CIR SSC.
PHOTOTOXICITY
MI at 100 ppm was not phototoxic or photosensitizing in guinea pig studies. No phototoxic effects were
observed in a study of 200 ppm MI in 12 female subjects. A photosensitization study of 200 ppm MI in 32 subjects
did not produce photoallergic reactions.
CLINICAL USE
Case Reports
Three cases of allergic contact dermatitis were reported in patients that had come into contact with coolant
solutions containing biocides. Patch testing in 2 of the patients revealed 2+ and 3+ reactions to MI, respectively.
An investigator in this study developed eczematous dermatitis while isolating coolant components and had a 2+
reaction to MI during patch testing. Another case study reported hand eczema in a diesel mechanic that was
exacerbated with the use of moist toilet paper. The diesel oil and the toilet paper the man came in contact with both
contained Kathon biocides. Positive reactions to MI were observed with patch testing. Two cases of occupational
contact allergy and dermatitis were reported in patients exposed to compounds containing the biocide MI. Patch
testing revealed +++ reactions to MI and Neolone 950. Four out of 14 workers at a Danish paint factory were
observed with contact dermatitis after exposure to paint additives containing 7-10% MI. Positive reactions were
observed in all 4 patients during patch testing.
A sampling of case reports and retrospective and multicenter studies reporting MI allergy are summarized
in Tables 3 and 4, respectively. Numerous reports of contact allergy, particularly to toilet wipes and water-based
wall paint containing MI, have been reported.30-38 Incidences of contact allergy to MI, tested separately from
MCI/MI, appear to be increasing in Europe in recent years.39-50
SUMMARY
In 2010, the Panel published the final report of the safety assessment of MI with the conclusion that “MI is
safe for use in cosmetic formulations at concentrations up to 100 ppm (0.01%)”. At the March 2013 CIR Expert
Panel meeting, the Panel reopened this safety assessment to gather and evaluate newly provided clinical data
indicating a higher than expected frequency of individuals who have allergic reactions to the preservative MI. This
summary only contains newly identified information on the MI. The original report should be consulted for the
information that was previously reviewed by the Panel.
According to the FDA’s VCRP database in 2007, MI had 1125 reported uses, with the majority of the uses
reported in non-coloring hair conditioners and shampoos. Industry reported the maximum use concentration range
to be 4 x 10-6% to 0.01%, with 0.01% reported in leave-on and rinse-off baby, non-coloring hair, and dermal contact
products. The information obtained from the VCRP in 2007 did not clearly distinguish cosmetic products in which
MI was used in combination with MCI from cosmetic products in which MI was used without MCI. This safety
assessment addresses the use of MI in cosmetic products that do not also contain MCI. In 2014, the VCRP database
indicated that MI was used as an ingredient in 745 cosmetic products that do not also contain MCI, with the majority
of the uses reported in leave-on products such as skin moisturizers. A survey of use concentrations conducted by the
Council in 2014 reported a maximum concentration of use range of 3.5 x 10-8% to 0.01%, with 0.01% reported in
multiple product categories including eye makeup remover, hair shampoos and conditioners, and skin care products
(both leave-on and rinse-off).
The European Union’s SCCS has a recently updated opinion on the use of MI and has found that in leave-
on cosmetic products (including “wet wipes”) no safe concentration has been adequately demonstrated for induction
or elicitation of contact allergy. In rinse-off cosmetic products, the SCCS has concluded that concentrations up to
0.0015% (15 ppm) MI are safe, in terms of induction of contact allergy, but recognized that there is no information
available to evaluate the potential for this ingredient to elicit contact allergy. Furthermore, the SCCS states that MI
should not be added to cosmetic products that contain MCI/MI.
A re-evaluation of the LLNA results reported in the published literature in an editorial article indicates that
MI should be categorized as a strong sensitizer, and not a moderate sensitizer as previously reported.
MI was named Allergen of the Year for 2013 by the American Contact Dermatitis Society due to the rise of
use of the preservative and the increased incidences of contact allergy being reported, especially in the European
Union. A standard series of patch testing includes the mixture MCI/MI, which may miss 40% of contact allergy to
MI alone due to the relatively low concentration of MI in the mixture. Recommendations have been made to test for
MI contact allergy separate from the MCI/MI, although there currently is no consensus of about the concentration of
MI that should be tested.
In sensitization studies conducted in 11 MI-allergic patients, the lowest eliciting dose in a patch test was
1.47 µg MI/cm2 (49 ppm). No reactions were observed at 0.441 µg MI/cm2 (15 ppm) or lower, nor were there any
reactions in the controls. In a ROAT, 7 patients (64%) reacted to 0.105 and 0.21 µg MI/cm2 and 2 patients (18%)
reacted to 0.0105 µg MI/cm2. In a HRIPT of 100 ppm MI, with or without various glycols, no evidence of induced
allergic contact dermatitis was observed in any of the subjects.
Numerous reports of contact allergy, particularly to toilet wipes and water-based wall paint containing MI,
have been reported. Incidences of contact allergy to MI, tested separately from MCI/MI, appear to be increasing in
Europe in recent years.
Cosmetics Europe and the CIR SCC conducted QRAs of MI in response to the increased incidences of
contact sensitization to MI in Europe. The QRA, which used a conservative NESIL of 15 µg/cm2/day that was
derived based on a WoE evaluation of data from 5 HRIPTs and 4 LLNAs, predicted that consumer exposures to 100
ppm MI in skin leave-on products and cosmetic wet wipes could induce skin sensitization, while exposures to the
same concentration in rinse-off products and hair care leave-on products would not induce skin sensitization.
DISCUSSION
The Panel noted the numerous reports of contact allergy to MI in Europe and the increased incidences of
contact allergy to MI observed in their own clinical experience. The Panel also noted that MI was named Allergen
of the Year for 2013 by the American Contact Dermatitis Society because of the increasing incidence of contact
allergy associated with the increasing use of this ingredient as a preservative in cosmetics. The Panel reviewed the
results of QRAs performed by Cosmetics Europe and the CIR Science and Support Committee using an appropriate
NESIL (i.e., 15 µg/cm2/day) selected based on a WoE evaluation of EC3 values from LLNAs and the results of
HRIPTs. The results supported the safety of the use of MI in rinse-off product categories at concentrations up to
100 ppm. However, the QRA indicated that MI use in many leave-on product categories would be safe only at
concentrations lower than 100 ppm. As shown in Table 2, for example, the AEL/CEL calculated for 100 ppm
(0.01%) MI in baby wipes was 0.13, which the Panel recognizes to be consistent with the reports of increasing
incidence of contact allergy associated with the use of MI in wet wipes.
Based on the QRA results, the Panel felt that the current limitation of 100 ppm supported the safety of MI
in rinse-off products. Nonetheless, they felt that leave-on products should be formulated to contain MI
concentrations below 100 ppm and to be non-sensitizing, as demonstrated, for example, by QRA estimates of safe
exposures (typically expressed in µg/cm2/day) for the relevant cosmetic product category.
The risk of inducing sensitization depends on the dose of MI per unit area of the skin exposed (e.g.,
expressed in units of µg/cm2/day). One type of cosmetic product will differ from another in the potential to cause
sensitization at a given MI concentration if they differ substantially in application rate, which depends on the
amount of product applied per day and the total surface area of the skin to which the product is applied. This helps
to explain why the risks associated with MI in rinse-off products are less than those associated with leave-on
products and, for instance, why the risks associated with exposures to MI in leave-on hair conditioners would likely
be substantially lower than those associated with MI in wipes.
It is important to note that appropriate exposure assumptions used in a QRA can vary depending on factors
such as differences in regional habits and practices, properties of the formulation, and degree to which conservative
default assumptions and exposure scenarios may be refined based on specific exposure data. The Panel stressed the
importance of clearly identifying and justifying the exposure assumptions, and the sources of the assumptions, used
in any QRA that might be conducted to predict concentrations of MI unlikely to induce sensitization from the use by
consumers of a specific cosmetic product or product category.
The Panel determined that the maximum MI concentration should never exceed 100 ppm (0.01%) in any
hair product, leave-on product, or rinse-off product, based on the potential for inducing sensitization and
concentrations greater than 100 ppm.
The Panel’s recommendations for MI in rinse-off and leave-on cosmetic products are intended to prevent
the induction of sensitization to MI. The Panel cautioned that following these recommendations may not necessarily
prevent the elicitation of allergic reactions in individuals who are already allergic to MI. Individuals sensitized to
MI should avoid products that contain MI.
The Panel discussed the issue of incidental inhalation exposure to MI in non-coloring hair sprays and hair
tonics or dressings. There were no chronic inhalation toxicity data identified or provided. MI reportedly is used at
concentrations up to 0.01% in cosmetic products that may be aerosolized. The Panel noted that 95% – 99% of
droplets/particles produced in cosmetic aerosols would not be respirable to any appreciable amount. Coupled with
the small actual exposures expected in the breathing zone and the absence of significant signs of toxicity in
subchronic, chronic, and reproductive and developmental animal studies reviewed previously by the Panel, the
available information indicates that incidental inhalation would not be a significant route of exposure that might lead
to local respiratory or systemic effects. A detailed discussion and summary of the Panel’s approach to evaluating
incidental inhalation exposures to ingredients in cosmetic products is available at http://www.cir-safety.org/cir-
findings.
CONCLUSION
The CIR Expert Panel concluded that MI is safe for use in rinse-off cosmetic products at concentrations up
to 100 ppm and safe in leave-on cosmetic products when they are formulated to be non-sensitizing, which may be
determined based on a QRA.
TABLES
Table 1. Historical and current use and concentration of use data for methylisothiazolinone.1,4,5
# of Uses
Max Conc of Use (%)
Data Year
2007*
2014**
2007
2014
Totals†
1125
745
4 x 10-6-0.01
3.5 x 10-8-0.01
Duration of Use
Leave-On
236
478
0.002-0.01
3.5 x 10-8-0.01
Rinse-Off
807
260
4.0 x 10-6-0.01
2.5 x 10-7-0.01
Diluted for (Bath) Use
82
7
NR
0.0002-0.01
Exposure Type
Eye Area
6
22
NR
0.00019-0.01
Incidental Ingestion NR 1 NR 0.0048
Incidental Inhalation-Spray
4; 86a;
54
b
3; 268a;
114
,b 0.005; 0.008-0.009a
0.0002-0.01a;
0.0002-0.01
c
Incidental Inhalation-Powder
1; 2d
114b
NR
NR
Dermal Contact
469
544
0.0008-0.01
3.5 x 10-8-0.01e,f
Deodorant (underarm)
2a
NR
NR
0.0095g
Hair - Non-Coloring
579
190
4.0 x 10-6-0.01
4.0 x 10-6-0.01
Hair-Coloring
76
NR
NR
5.6 x 10-5-0.0095
Nail
1
5
NR
0.0002-0.006
Mucous Membrane
241
103
0.0015-0.01
9.0 x 10-7-0.01
Baby Products
14
6
0.002-0.01h
0.0002-0.0075
* Data provided are not clear as to whether uses are MI alone or include uses of MI/MCI.
** Data provided are for uses of MI alone.
NR = Not reported
†Because each ingredient may be used in cosmetics with multiple exposure types, the sum of all exposure types
may not equal the sum of total uses.
a. Includes products that can be sprays, but it is not known whether the reported uses are sprays.
b.
Not specified whether a powder or a spray, so this information is captured for both categories of incidental
inhalation.
c. 0.01% in an aerosol hair spray; 0.0002-0.01% in a pump hair spray; 0.006-0.0095% in a pump hair tonic or
dressing.
d. Includes products that can be powders, but it is not known whether the reported uses are powders.
e. 0.00023-0.01% in a hand soap; 0.01% in a foot scrub.
f
. The Council survey requested that wipe products be identified. One product containing MI was identified as
being used as a skin cleansing wipe at a concentration of 0.005%.
g. Not a spray deodorant.
h. 0.01% in baby wipes.
Table 2. Quantitative risk assessment of methylisothiazolinone (MI) at highest maximum use concentration (100 ppm) in cosmetic products.
28
Product Category*
Product Amount
Applied / day
(µg/cm
2
)
Consumer Exposure
Level
(CEL; µg/cm
2
/day)
Sensitization
Assessment
Factor
(SAF)
Acceptable Exposure
Level
(AEL; µg/cm
2
/day)**
AEL/CEL
Baby shampoo
200
0.02
100
0.15
7.50
Baby lotions, oils, powders, creams
2200
0.22
300
0.05
0.23
Baby wipes
4000
0.40
300
0.05
0.13
Other baby products (powders and talcs)
4200
0.42
100
0.15
0.36
Other baby products (washes)
200
0.02
100
0.15
7.50
Bath oils, tablets and salts
200
0.02
100
0.15
7.50
Bath soaps and detergents
10
<0.01
100
0.15
150
Bubble baths
200
0.02
100
0.15
7.50
Other bath preparations
200
0.02
100
0.15
7.50
Eyebrow pencil
2200
0.22
300
0.05
0.23
Eyeliners
2170
0.22
300
0.05
0.23
Eye shadow
2170
0.22
300
0.05
0.23
Eye lotion
2170
0.22
300
0.05
0.23
Eye makeup remover
900
0.09
100
0.15
1.67
Mascara
2170
0.22
300
0.05
0.23
Other eye makeup
2170
0.22
300
0.05
0.23
Cologne and toilet waters
17700
1.77
100
0.15
0.08
Blushers
1000
0.10
100
0.15
1.50
Other fragrance products
2200
0.22
100
0.15
0.68
Hair conditioners
200
0.02
100
0.15
7.50
Hair sprays (aerosol fixatives)
1390
0.14
100
0.15
1.08
Hair sprays (pump)
2200
0.22
100
0.15
0.68
Hair straighteners
4200
0.42
100
0.15
0.36
Permanent waves
4200
0.42
100
0.15
0.36
Rinses (noncoloring)
170
0.02
100
0.15
8.82
Shampoos (noncoloring)
170
0.02
100
0.15
8.82
Tonics, dressings and other hair grooming
aids
990
0.10
100
0.15
1.52
Table 2. Quantitative risk assessment of methylisothiazolinone (MI) at highest maximum use concentration (100 ppm) in cosmetic products.
28
Product Category*
Product Amount
Applied / day
(µg/cm
2
)
Consumer Exposure
Level
(CEL; µg/cm
2
/day)
Sensitization
Assessment
Factor
(SAF)
Acceptable Exposure
Level
(AEL; µg/cm
2
/day)**
AEL/CEL
Wave sets
4200
0.42
100
0.15
0.36
Other noncoloring hair products
1000
0.10
100
0.15
1.50
***Hair dyes and colors
1000
0.10
100
0.15
1.50
***Hair tints
990
0.10
100
0.15
1.52
Hair rinses (coloring)
200
0.02
100
0.15
7.50
***Hair bleaches
1000
0.10
100
0.15
1.50
Other hair coloring preparations
1000
0.10
100
0.15
1.50
Face powders
1000
0.10
100
0.15
1.50
Foundations
3170
0.32
100
0.15
0.47
Lipsticks
11460
1.15
300
0.05
0.04
Other makeup preparations
4200
0.42
100
0.15
0.36
Other manicuring preparations
1000
0.10
100
0.15
1.50
Other personal cleanliness products
4400
0.44
300
0.05
0.11
Aftershave lotions
2210
0.22
100
0.15
0.68
Preshave lotions (all types)
2200
0.22
100
0.15
0.68
Shaving cream (aerosol, brushless and
lather)
70
0.01
300
0.05
7.14
Shaving soaps (cakes, sticks, etc.)
70
0.01
300
0.05
7.14
Other shaving preparations
2200
0.22
100
0.15
0.68
Skin cleansing (cold creams, cleansing
lotions, liquids and pads)
900
0.09
100
0.15
1.67
Depilatories
200
0.02
100
0.15
7.50
Face and neck creams, lotions, powders
and sprays
2700
0.27
100
0.15
0.56
Body and hand creams, lotions and
powders
1120
0.11
300
0.05
0.45
Moisturizers
2700
0.27
100
0.15
0.56
Nail care creams and lotions
970
0.10
100
0.15
1.55
Deodorants (underarm)
8500
0.85
300
0.05
0.06
Night creams, lotions, powders, and sprays
3170
0.32
100
0.15
0.47
Paste masks (mud packs)
4200
0.42
100
0.15
0.36
Table 2. Quantitative risk assessment of methylisothiazolinone (MI) at highest maximum use concentration (100 ppm) in cosmetic products.
28
Product Category*
Product Amount
Applied / day
(µg/cm
2
)
Consumer Exposure
Level
(CEL; µg/cm
2
/day)
Sensitization
Assessment
Factor
(SAF)
Acceptable Exposure
Level
(AEL; µg/cm
2
/day)**
AEL/CEL
Skin fresheners
150
0.02
100
0.15
10
Other skin care products
2200
0.22
100
0.15
0.68
Suntan gels, creams, liquids and sprays
2200
0.22
100
0.15
0.68
Indoor tanning preparations
2200
0.22
100
0.15
0.68
Other tanning preparations
2200
0.22
100
0.15
0.68
Foot powders and sprays
2200
0.22
100
0.15
0.68
Shaded rows indicate the ratio of AEL x CEL-1 is less than 1.
*Exposure values assumed for each product category were from the IFRA RIFM QRA Information Booklet (2011)51 and Api et al. (2008)52
**Based on No Expected Sensitizing Induction Level (NESIL) of 15 µg/cm2/day
***Note that this product category may be diluted prior to application
Table 3. Case studies
Mode of Contact
Patient(s)
Indication
Reference
MI in toilet wipes, carpet glue (100
ppm), and water-based paint (100
ppm and also 100 ppm MCI/MI)
55-year-old non-
atopic male
employed as a
bank clerk
-eczematous eruptions on the face, neck, retroauricular
area, and forearms that appeared after exposure to fresh
paint at his place of employment;
-earlier in the year, suffered from pruritus ani and
occasional eczema in the perineal area after use with a
toilet wipe, facial dermatitis following first uses of a
perfume after shaving, and dermatitis following use of
deodorant;
-
previous patch tests with a baseline and cosmetic series
were negative;
-further testing performed with wipes, perfume, the
individual ingredients of these products, and fragrance
mix II and its components yielded positive reactions to
the wipes, perfume, MI, and fragrance mix II on day 2;
-day 2 results from additional testing with repeated
baseline series and aqueous dilutions of MI and
MCI/MI found +? reaction to 100 ppm MCI/MI, ++
reaction to 1000 ppm MI, and + reaction to a brand of
wipes;
-on day 4, + or +? reactions to 10, 50, and 100 ppm
MCI/MI, + reaction to 10 ppm MI, ++ reactions to 100
and 500 ppm MI, +++ reactions to 1000 ppm MI, and
++ reaction to the wipes.
30
toilet wipes that contain 90 ppm MI
and water-based paint that
contained 0.01% MI and 0.01%
MCI/MI
62-year-old non-
atopic female
-eczematous eruptions affecting face, trunk, arms, and
legs that had started 1 month earlier as acute eczema in
the perineal area that the patient attempted to treat with
feminine hygiene products;
-symptoms occurred 2 months following the initial use
of a toilet wipe;
-patch testing with European baseline, cosmetic series,
the toilet wipe, and a feminine hygiene product yielded
positive reactions to the wipe (++ days 2 and 4) and the
feminine hygiene product (+ day 4) as well as to 100
ppm MCI/MI (++ days 2 and 4);
-patient returned 4 months later with 1-week history of
swollen eyelids and face with severe itching and
burning following exposure to water-
based wall paint in
her home;
-patch testing with paint produced a ++ reaction.
30
toilet wipes that contain 90 ppm MI
50-year-old non-
atopic female
-patient presented with a 1-year history of perianal
dermatitis following the use of moist toilet paper to
control anal pruritus;
-patch testing with European baseline, 1000 ppm MI,
and 200 ppm MCI/MI yielded a + reaction to 200 ppm
MCI/MI (day 4) and a + (day 2) and ++ (day 4) reaction
to 1000 ppm MI.
30
toilet wipes that contain 90 ppm MI
43-year-old non-
atopic female
-patient presented with a 3-month history of eczematous
lesions on the genital and perianal area;
-patch testing with European baseline, 1000 ppm MI,
and toilet wipe yielded a + (day 2) and ++ (day 4)
reaction to 1000 ppm MI.
30
toilet wipes that contain 90 ppm MI
20-year-old non-
atopic female
-perianal itch and genital lesions that had lasted 4 years
that the patient treated under physician’s guidance with
toilet wipes and then worsened into oozing dermatitis;
-patch testing with European baseline and toilet wipe
yielded a ++ reaction (day 4) to 100 MCI/MI, a ++
reaction (day 4) to 1000 ppm MI, and ++ reactions (day
2 and 4) to the wipes.
30
eye cleansing lotion that contained
MI
57-year-old atopic
female
-patient presented eczematous lesions to the eyelids,
mainly localized in corners of eyes, with 6 months
duration;
-patch testing with European baseline, cosmetic series,
and 1000 ppm MI yielded + reactions (days 2 and 4) to
1000 ppm MI.
30
Table 3. Case studies
Mode of Contact
Patient(s)
Indication
Reference
toilet wipes that contain 90 ppm MI
44-year-old atopic
female
-patient presented pruritus and perianal eczema with 1-
year duration following use of toilet wipes that were
initially used 2 years prior;
-patient also had reactions previously to perfumed bath
salts and has experienced severe scalp itch;
-patch testing with European baseline, cosmetic series,
10 and 1000 ppm MI, 10 ppm M
CI/MI, fragrance mix II
ingredients, lavender oil, and the toilet wipe yielded a
+++ reactions (days 2 and 4) to 100 ppm MCI/MI, +++
(day 2) and ++ (day 4) reactions to 1000 ppm MI, a +
(day 4) reaction to 10 ppm MI, and ++ reactions (days 2
and 4) to the toilet wipes.
30
deodorant containing MI used for 2
weeks
37-year-old atopic
woman with past
history of jewelry
intolerance and no
history for
previous skin
reactions to
perfumes and
deodorants
-eczematous lesions affecting both axillae that cleared
after treatment with topical corticosteroids;
-patch testing with Portuguese baseline series, a
fragrance series, and to patient’s own product yielded
++ reactions to nickel, 100 ppm MCI/MI, and to the
deodorant;
-
repeated open allocation test on the volar forearm with
the deodorant was strongly positive on day 2;
-patch testing with 200 ppm MI yielded at ++ reaction
on day 2.
32
water-based wall paint containing
0.0053% (53 ppm ) MI that had
been applied to bedroom walls
4-year-old girl
with mild atopic
dermatitis since
birth
-papular dermatitis affecting face, including nasolabial
folds and lower eyelids, followed by generalized skin
lesions accentuated at the knee and elbow folds;
- rash “waxed and waned” for about 4 weeks with
corticosteroid treatment while patient continued to sleep
in painted bedroom and then started to clear;
-
patch testing with adapted European baseline series for
children had a +
reaction on D4 for MCI/MI at 0.01% or
100 ppm;
-
child had history of extensive dermatitis following use
of a moist toilet paper that contained MI but not MCI.
31
toilet cleaner containing 10 ppm
MI with additional occupational
exposures
32-year-old man
-severe widespread dermatitis caused by heavy exposure
to MCI/MI and MI while working at a glue factory;
-patch testing revealed + reaction to MCI/MI and ++
reaction to MI;
-during treatment, patient also developed a 5-cm
eczematous reaction on left inner thigh extending to the
buttock;
-patient had a new toilet cleaner in home toilet that
contained both MCI and MI at 11 ppm and 10 ppm,
respectively;
-eczema improved after removal of toilet cleaner from
home.
33
wall paint containing MI
23-year-old non-
atopic woman
-initial symptoms of facial dermatitis including
periorbital
edema that progressed to vesicular dermatitis
began 2 months prior to examination after the patient
started working at a restaurant that had just been freshly
painted;
-patient also experienced burning sensation of the
cheeks, malaise, and dizziness that worsened the more
consecutive days she worked and improved during days
off;
-patch testing with European baseline series, an
extended series with the patient’s own cosmetic
products, and an extended series with fragrance
ingredients yielded ++ reactions to 0.01% MCI/MI and
to 0.2% MI;
-after initial airborne exposure, patch testing and onset
of dermatitis, patient was re-exposed to MI in a
cleansing product to which she had never been exposed
and immediately experience marked aggravation of
facial dermatitis.
34
Table 3. Case studies
Mode of Contact
Patient(s)
Indication
Reference
wall paint containing MI
36-year-old non-
atopic male
-dermatitis on the legs that spread to the face,
shoulders, back, abdomen, and arms as well as intense
headache that worsened while the patient was at work,
but improved on days off;
-initial patch testing showed ++ reaction to 2%
formaldehyde and +? Reactions to fragrance and 0.2%
MI;
-symptoms disappeared after 2.5 months of sick leave,
but reappeared after patient moved to a newly
refurbished apartment;
-both the apartment and casino (workplace) had been
painted with a paint that contained MI.
35
wall paints containing 1.2-187 ppm
MI, 0.3-10 ppm MCI/MI, and 8.5 -
187ppm benzisothiazolinone (BIT)
57-year-old non-
atopic male with a
long history of
hand eczema and
contact allergy
-patient developed facial erythema, cough, and
difficulty breathing a few days after using paint
containing isothiazolinones;
-during the same time period, the patient was
participating in a clinical investigation of the dose-
response relationship of MI in MI-allergic patients;
-patient previously had positive patch tests to
formaldehyde, quaternium-15, DMDM hydantoin, p-
phenylenediamine, melamine formaldehyde, urea
formaldehyde, MCI/MI, and MI;
-treatment with prednisolone, cetirizine, and
corticosteroids helped alleviate the symptoms while at
the hospital but all symptoms reoccurred when the
patient returned home and even worsened to include
dermatitis reactions at the MI test sites from the dose-
response study.
35
wall paint containing MI
53-year-old non-
atopic female
-patient presented with severe respiratory symptoms,
erythema in the face, and edema around the eyes that
occurred after the patient moved into a freshly painted
apartment;
- patch testing with the European baseline series, an
extended standard, and a paint series yielded + reactions
to 2000 ppm MI and 5% farnesol;
-symptoms resolved after the patient moved out of her
apartment.
36
“waist reduction belt” contact gel
containing MI
68-year-old male
with longstanding
perianal dermatitis
and recurrent hand
eczema
-patient presented with pruritic, erythematous patches
on abdomen corresponding to contact areas for the gel
of a waist reduction belt;
-patient used the device 3x/day for 10 min each for a
few days before developing progressive skin changes;
-patch testing with baseline series, preservative series,
5% propylene glycol, and 3 ultrasonic contact gels,
including the one used by the patient, yielded doubtful
reactions to fragrance mix I and MCI/MI and ++
reaction to 0.05% MI;
-
labeling of the contact gel used by patient indicated the
presence of both MCI and MI.
37
household wipes and skin
cleansing products containing MI
39-year-old non-
atopic female
employed as a
neonate nurse
-patient presented with eczematous skin lesions on the
arms, neck and trunk of 7-month duration;
-patient also developed palmar hand dermatitis 2-
months later, after receiving treatment for the initial
symptoms;
-patient had previously developed a severe eczematous
reaction on the hands to water-soluble paint and eyelid
dermatitis while her house was being painted;
-patient had daily contact to nitrile gloves, hospital
soap, skin cleansing products, baby wipes, household
wipes, and rubber;
-patch testing with the European baseline series,
cosmetic and rubber series, and patient’s products and
the known allergens in them yielded + reactions to 500
ppm MI, 5% Compositae mix, a cosmetic body milk
tested “as is” and a household wipe tested “as is”;
-household wipes were analyzed by a lab that
determined they contained 60 ppm MCI/MI, however,
the patient tested negative to 100 ppm MCI/MI.
38
Table 4. Retrospective and multicenter studies
Number of dermatitis
patients tested, location
Concentration
of MI tested
Years analyzed
Results
Reference
2536; Gentofte, Denmark
2000 ppm in
supplemented
European
baseline series
May 2006 – Feb
2010
-1.5% (37/2536) of the patients patch-tested
with MI had contact allergy;
-MI contact allergy more often associated with
occupational exposure, hand eczema, and age
above 40 years.
-12/37 cases (32%) were cosmetics exposure
and 11/37 cases (30%) were occupational
exposure, with half of these occurring in
painters
39
10,821; Finland
0.1% (1000
ppm) and
0.03% (300
ppm) in
addition to
being tested
with MCI/MI
2006-2008
-1.4% and 0.6% had positive patch test
reactions to 0.1% and 0.03% MI, respectively.
-66% of those who were MI-positive were also
positive to 100 ppm MCI/MI
-Of 33 patients that submitted to a use test, 10
had positive results
40
653; Australia
200 ppm in the
Australian
baseline series;
testing with100
and 200 ppm
MCI/MI also
performed
January 1, 2011
to June 30, 2012
-43 (7%) reactions were observed, 23 (4%) of
which were deemed relevant;
-7 of the patients were parents of young
children with hand dermatitis caused by
allergic contact dermatitis to MI in baby wipes;
-
remaining patients reacted to MI in shampoos,
conditioners, deodorants, moisturizers, a skin
cleanser, and a facial wipe;
-3 patients had occupational exposure to hand
cleansers;
-34/43 patients (79%) had concomitant
reactions with MCI/MI.
41
2766 to MI, 2802 to MCI/MI,
and 2413 to BIT; Gentofte,
Denmark
2000 ppm MI,
100 ppm
MCI/MI, and
1000 ppm BIT
2010-2012
-contact allergy to MI increased from 2.0% in
2010 to 3.7% in 2012;
-contact allergy to MCI/MI increased from
1.0% in 2010 to 2.4% in 2012;
-MI-allergic patients tended to have
occupational exposure, hand and face
dermatitis, and were > 40-years-old;
-cosmetic products were the most common
substances causing relevant exposure in both
MCI/MI- and MI-allergic patients.
42
1289; London
500 ppm MI in
a cosmetics/
face patch test
series
July 2010 to
September 2012
-in 2010, 1/85 patients (0.5%) had a positive
reaction to MI;
-in 2011, 18/521 patients (3.5%) had a positive
reaction to MI;
-in 2012, 33/584 patients (5.7% had a positive
reaction to MI;
-reactions appeared to be more prevalent in
patients > 40-years-old.
43
219 painters and 1095
controls; Gentofte, Denmark
0.01% MCI/MI
in European
baseline series
with testing
with MI and
other
isothiazolinones
of unreported
concentrations
performed as
dictated by
patient’s
exposure
history
2001 to 2010
-22/219 (10%) of painters had positive
reactions to MCI/MI (p<0.0001);
-11/41 (27%) of painters had positive reactions
to MI;
-5/21 (25%) of painters had positive reactions
to octylisothiazolinone;
-7/37 (19%) of painters had positive reactions
to benzisothiazolinone (BIT).
44
Table 4. Retrospective and multicenter studies
Number of dermatitis
patients tested, location
Concentration
of MI tested
Years analyzed
Results
Reference
~120,000 with baseline series
and ~13,000 with preservative
series; Germany, Switzerland,
Austria (IVDK network)
0.05% MI in
pet. and 0.01%
MCI/MI in pet.
January 1996 to
December 2009
-2.22% of patients had positive reactions to
MCI/MI in baseline series;
-
1.54% of patients had positive reactions to MI
in preservative series;
-67% (134/199) of MI positive patients also
reacted to MCI/MI;
-MI sensitization observed more often with
occupational dermatitis.
45
563 and 2056 for 2 different
concentrations of MI, 2489 for
MCI/MI; Leeds, UK
0.002% MI
(2009-2012);
0.2% (2011-
2012); and
0.02% MCI/MI
(2008-2012)
January 2008 to
June 2012
-3.8% and 4.6% of patients had positive
reactions to 0.2% MI in 2011 and 2012,
respectively;
-percentage of patients positive to 0.02% MI
increased from 0.6% in 2009 to 2.5% in 2012;
-percentage of patients positive to 0.02%
MCI/MI increased from 0.9% in 2008 to 4.9%
in 2012.
46
245 for MI and ~25,000 for
MCI/MI; European
Surveillance System on
Contact Allergy Network
0.05% MI and
0.01% for
MCI/MI
2007 to 2008
-2.6% of patients (n=245 in the Netherlands)
had positive reactions to MI;
-additional results reported were 1.1% and
1.7% positive reactions in 281 Finnish patients
to 0.03% MI and 0.1% MI, respectively, and
1.4% positive reactions in 1280 Danish patients
to 0.2% MI;
-for MCI/MI, an average of 2.5% of the
patients across 11 countries had positive
reactions.
47
28,922; IVDK network
0.05% MI (500
ppm) in water
2009 to 2012
-an average of 3.83% of patients tested had
positive reactions to MI;
-prevalence of MI sensitization reported to
have increased from 1.94% in 2009 to 6.02% in
2012;
-increases observed in female patients > 40
years-
old, patients with face dermatitis, and use
of cosmetics.
48
477; France
0.02% and
0.05% (200 and
500 ppm) MI
2 year period,
years not
reported
-out of 477 patients tested with European
baseline and two concentrations of MI, 10
patients had relevant reactions;
-all 10 patients reaction to 0.05% MI, while
only 5 reacted to 0.02% MI;
-only 1 patient of the 10 reacted to 100 ppm
MCI/MI
-all 5 patients that had been tested with
personal care products containing MI reacted.
49
12,427 in 2009, 12,802 in
2010, and 12,575 in 2011;
IVDK network
500 ppm MI
and 100 ppm
MCI/MI
2009-2011
-1.9%, 3.4%, and 4.4% positive reactions in
2009, 2010, and 2011, respectively;
-proportion of MI-positive patients in those
reacting to MCI/MI increased from 43% to
59% between 2009 and 2011.
50
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