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EC number: 275-702-5
CAS number: 71617-10-2
Human breast milk samples were taken from six women and
examined for the presence of sunscreen agents Homosalate (HMS),
Isopentyl p-methoxycinnamate (IMZ), Benzophenone-3 (BP-3),
Methylbenzylidenecamphor (MBC), Octyl Dimethyl PABA (DABI) and 2
-ethylhexyl 4- methoxycinnamate (OMZ). It has been reported that up to
2% of the applied substances can be absorbed via the skin according to
manufacturers information. Glass-columns filled with differently
acitvated silica gel were used for the extraction of each of the 10 ml
milk sampIes. The extracts were cleaned by gel permeation
chromatography, afterwards reduced to a volume of 150 [ll and
quantitatively analysed by Capillary Gaschromatography/ Mass
Spectrometry in the SIM-mode. BP-3 and 2 -ethylhexyl 4 -methoxycinnamate
were unambiguously detectable in five of the six investigated samples at
a concentration range between 16 and 417 ng/g (fat basis). However,
isopentyl p-methoxycinnamate was not detected in any of the samples.
This information would add some support to the dermal absorption study
in humans in which it was concluded that dermal absorption of isopentyl
p-methoxycinnamate did not occur.
Three dermal absorption/penetration studies with isopentyl p-methoxycinnamate were performed on pigs (ex vivo), rats (in vivo) and humans and information from a reference by Hany and Nagel (1995) on the potential for the appearance of isopentyl p-methoxycinnamate and other sunscreen agents, including the read-across substance 2-ethylhexyl 4-methoxycinnamate, in human breast milk was evaluated.
The toxicokinetics of isopentyl
p-methoxycinnamate was primarily studied in 3 dermal
absorption/penetration studies in pigs (ex vivo), rats (in vivo), and
humans (all classified as Klimisch 2 studies). These studies provided
information on the potential absorption of Isopentyl p-methoxycinnamate.
In addition, Hany and Nagel (1995) published an analytical study
(Klimisch 3) on the determination of various sunscreen agents, including
isopentyl p-methoxycinnamate and the read-across substance (2
-ethylhexyl 4 -methoxycinnamate) in breast milk (see the attached pdf
file). No data was available on the metabolism of isopentyl
p-methoxycinnamate, however, some excretion data was presented as part
of the rat dermal absorption study:
test substance was applied at 0.157 and 0.164 mg/cm2on the
skin of male and female volunteers. Using strip methodology, more than
50% of the administered radioactivity was recovered in the first two
strips. A mean of 88.5-94.3% of the administered amount of radioactivity
was recovered in the 20 strips, the predominant amount of the
radioactivity was therefore detected on or in the epidermis. In the
upper layers of the epidermis more radioactivity was found than in the
lower layers and 0.5% of the applied radioactivity was still detected in
the last strip. These results suggested that isopentyl
p-methoxycinnamate did not significantly penetrate into the skin of
human volunteers from two different formulations (there were no
significant differences between the two formulations used - oil in water
and water in oil).
Rats (in vivo):
18-23 mg of the [14C]-radiolabelled
test substance was applied to the skin of male and female Sprague-Dawley
rats. Absorption increased with time, with the radioactivity in and on
the treated area of the skin decreasing with the duration of the
percutaneous application. The absorbed amount of [14C]-labelled
test substance was excreted mainly via urine with the amount of 14C
remaining in the carcass and various organs being rather low (0.01 -
1.5%) at the different times after application, indicating that the
absorbed amount was excreted rapidly.
Pigs (ex vivo):
The dermal absorption /
penetration of isopentyl p-methoxycinnamate in oil/water and water/oil lotions
were determined in an ex vivo / in vitro-model (using excised porcine
back skin) at 3, 6, 16, and 24 h after topical application to the skin
samples. Based on the results obtained from this skin penetration study
using especially prepared back skin samples from female pigs, it can be
concluded that the test substance showed dermal penetration and
permeation up to 37% or 58% after 24 h in oil/water-lotion and
water/oil-lotion respectively, whereas no absorption of the test
substance occurred which could result in the test substance being
available in systemic circulation.
In summary, isopentyl p-methoxy showed
penetration/permeation up to 58% 24 h post application, but no
absorption was recorded in the ex vivo pig skin model. In rats, the
radiolabeled substance was absorbed through the skin up to 11.2% 24h
post application and distributed in many organs before excretion via
urine. However, the human study showed no significant penetration into
the skin of human volunteers. The distribution study in humans (Hany and
Nagel, 1995) is worthy of mention as, although it is an unreliable
(Klimisch 3) study due to the small group size (6), it confirms the lack
of distribution into breast milk of isopentyl p-methoxycinnamate
following dermal application,in comparison with two other sunscreen
agents,benzophennone-3 and the read-across substance, 2 -ethylhexyl 4
-methoxycinnamate, which were detected in 4 and 2 of the samples
When comparing the information from these studies with
the opinion on "Basic Criteria for the in vitro Assessment of Dermal
Absorption of Cosmetic Ingredients" (SCCP March 2006) it is concluded
that the study in pigs complies most directly with the recommendations.
Results from this study demonstrate skin penetration following
application of isopentyl p-methoxycinnamate to the skin preparations
without any "penetrated substances" being detected in the receptor
fluid. Therefore, the test substance retained by the stratum corneum is
not considered to be absorbed and thus is not considered to contribute
to a systemic dose.
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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