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EC number: 275-702-5
CAS number: 71617-10-2
The skin irritation properties of isopentyl p-methoxycinnamate were investigated in an in vivo study in rabbits. In addition a double-blind, randomised assessment of the irritant potential of sunscreen chemical dilutions, including isopentyl p-methoxycinnamate, was conducted in human volunteers.The eye irritation properties of this compound were assessed in two in vitro studies, (HET-CAM and BCOP) test, as well as in an in vivo study in rabbitsThe potential respiratory irritation properties of isopentyl p-methoxycinnamate were not studied.
Under the experimental conditions described in the report, the mean
score for erythema and oedema in the 4 rabbits used were as follow:
The primary skin irritant effect of Neo Heliopan E1000 was
investigated according to the method recommended in the current OECD
guideline no. 404, "Acute Dermal Irritation/ Corrosion", 1992, and in
the current EC guideline B.4 "Acute toxicity (skin irritation)", dated
29.12.1992. The study was extended to investigate 5 different
concentrations of the test article and a vehicle control on each animal.
Four albinos rabbits were exposed to different concentrations of
the test article at 6 skin sites on the back. After 4 h of exposure, the
test article was removed and the skin was examined 1, 24, 48, and 72 h
after termination of exposure.
Slight skin erythma was observed at 1 to 48 h after termination of
exposure of the neat test article. Apart from that, no abnormalities
Accordingly, isopentyl p-methoxycinnamate was rated
as being not irritating to the skin of rabbits.
Group I conjunctivae
Group II conjunctivae
Group III conjunctivae
The eye irritation potential of 2-ethylhexyl 4-methoxycinnamate, a close
structural analogue of isopentyl p-methoxycinnamate, was evalauted in a
Draize test in albino rabbits.
was injected into the left eye of 3 albino rabbits without rinsing, the
left eye of another 3 albino rabbits were rinsed after 2 and 4 seconds,
resp. Cornea, iris, and conjunctivae were examined. A slight irritation
of the conjunctivae was observed during the few hours after application
. This irritation is manifested by the presence of some more capillaries
injected into the eye treated than on the eye not treated. No effect,
however small, could be detected 24 h after application of the test
In view of the close chemical relationship between isopentyl
p-methoxycinnamate and Neo Heliopan AV, the negative findings obtained
provide further evidence for the non-eye-irritancy of isopentyl
p-methoxycinnamate in rabbits.
The in vivo skin irritation test in rabbits was
conducted according to OECD guideline no. 404 and EU guideline B 4. Five
concentrations of the test article were studied on each animal.
Accordingly, 4 albino rabbits were exposed to 5 different concentrations
of the test article and a vehicle control at 6 skin sites on the back.
After 4 h of exposure, the test items were removed and the skin was
examined at 1, 24, 48, and 72 h thereafter.
Slight skin erythma was observed at 1 to 48 h after
termination of exposure of the neat test article. No further
abnormalities were observed. Accordingly, isopentyl p-methoxycinnamate
was rated as being not irritating to the skin of rabbits.
Further information on the skin irritation
potential of isopentyl p-methoxycinnamate is available from a recently
conducted double- blind, randomized photoirritation patch test in humans
(Kerr et al. 2009; see the attached pdf file). Out of the 80 subjects
analysed in this study, 1 and 3 subjects showed "doubtful" or "weakly
positive" photoirritant reactions after the application of isopentyl
p-methoxycinnamate at concentrations of 5% and 10%, respectively. No
photoirritant reactions were observed when isopentyl p-methoxycinnamate
was applied at a concentration of 2%. These findings suggest that
isopentyl p-methoxycinnamate at higher concentrations might have a
certain, albeit low, incidence (≤ 5%) to cause photoirritant skin
In the HET-CAM test, 0.2 mL of a solution or
suspension of isopentyl p-methoxycinnamate (1% and 10% in olive oil) was
applied to the Chorioallantois membrane of hen's eggs and incubated for
10 days. At 0.5, 2, and 5 min after application of the test item, the
capillary blood vessels and the egg white were inspected for vascular
injections, haemorrhage, and coagulation and the severity of the effects
was rated using a numerical, time-dependent scale. Isopentyl
p-methoxycinnamate was found to be "practically non- irritant" in this
In the BCOP test, fresh bovine corneas, which had
been pre- incubated with complete minimum essential medium at 32±1°C for
1 h, were treated with 750 µL of undiluted isopentyl p-methoxycinnamate
or two dilutions (1% and 10%) of the test item in olive oil for 10 min
at 32±1°C. NaOH (10% solution in demineralised water) and physiological
NaCl solution were used as positive and negative control, respectively.
3 replicates were used for each treatment group. After removal of the
test item and 2 h post- incubation, opacity and permeability values were
While the positive control induced very severe
irritation on the cornea, the negative control showed no irritation.
Similarly, isopentyl p-methoxycinnamate did not induce any irritation at
any of the three tested concentrations.
In the in vivo test for eye irritation/corrosion,
eight rabbits were treated with 0.1 mL of isopentyl p-methoxycinnamate
at a concentration of 50% in olive oil. The test item was applied in the
conjunctival sac of the animals. After an exposure period of 1 min, the
test item was rinsed off with physiological saline in 4 animals, whereas
the test item was left on the eyes of the remaining 4 animals (no data
given on the duration of the overall exposure period and the observation
period). No irritant or corrosive effects were observed in any of the
animals. However, all the data was not available for full assessment of
this endpoint for isopentyl p-methoxycinnamate and the study was
assigned a Klimisch 4 (not assignable). Therefore, data was read-across
from the in vivo rabbit eye irritation study conducted with the
read-across substance, 2 -ethylhexyl 4 -methoxycinnamate (Klimisch 2).
Data from this study was also negative in this respect.
In summary,the negative result of the in vitro eye
irritation findings for isopentyl p-methoxycinnamate were corroborated
by the results of the HET-CAM and the BCOP test conducted with 2
-ethylhexyl 4 -methoxycinnamate. Similarly, 2 -ethylhexyl 4
-methoxycinnamate was negative in an in vivo eye irritation test in
rabbits, thereby further corroborating the non-irritancy of isopentyl
p-methoxycinnamate to the eye.
Justification for selection of skin irritation / corrosion
Guideline study performed in accordance with GLP
Justification for selection of eye irritation endpoint:
The selected study is a Guideline study performed in accordance with
GLP and has a Klimisch score of 2 (reliable with restrictions). The
read-across substance 2-ethylhexyl 4-methoxycinnamate is of strong
structural similarity with isopentyl p-methoxycinnamate such that
similarities are expected in the eye irritation profile. The in vivo
rabbit eye test with isopentyl p-methoxycinnamate is Klimisch score 4
(not assignable) due to the non-availability of the data. The in vitro
eye irritation studies produced negative results for both substances.
Based on the results of the skin and eye irritation
studies given above, isopentyl p-methoxycinnamate is not classified as
skin or eye irritant according to the current EU-CLP regulation.
A classification of isopentyl p-methoxycinnamate
for respiratory irritation is not possible, as no respiratory irritation
studies were conducted with this compound.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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