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EC number: 249-044-4
CAS number: 28472-97-1
Table 1: Results of LLNA
Concentration of test substance (% w/v)
Number of lymph nodes assayed
Counts per minute (cpm)
cpm per lymph node (x 10-2)
Test: control ratio (Stimulation index)
0 (vehicle only)
Justification for grouping of substances and read-across
There are only limited data available on the skin sensitisation
potential of diisodecyl azelate (CAS 28472-97-1). In order to fulfil the
standard information requirements set out in Annex VII, 8.3, in
accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006,
read-across from structurally related substances was conducted.
In accordance with Article 13 (1) of Regulation (EC) No 1907/2006,
"information on intrinsic properties of substances may be generated by
means other than tests, provided that the conditions set out in Annex XI
are met.” In particular for human toxicity, information shall be
generated whenever possible by means other than vertebrate animal tests,
which includes the use of information from structurally related
substances (grouping or read-across).
Having regard to the general rules for grouping of substances and
read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC)
No 1907/2006 whereby substances may be predicted as similar provided
that their physicochemical, toxicological and ecotoxicological
properties are likely to be similar or follow a regular pattern as a
result of structural similarity.
Overview of skin sensitisation
RA: CAS 27178-16-1RA: CAS 103-24-2
RA: CAS 897626-46-9
RA: CAS 7491-02-3
Experimental result:not sensitising
Experimental result:not sensitising (human data)
(a) The substance subject to registration is indicated in bold font.
(b) Reference (read-across) substances are indicated in normal font.
Lack of data for a given endpoint is indicated by “--“.
The above mentioned substances are considered to be similar on the basis
of the structural similar properties and/or activities. The available
endpoint information is used to predict the same endpoints for
diisodecyl azelate (CAS 28472-97-1). A detailed analogue approach
justification is provided in the technical dossier (see IUCLID Section
The sensitising potential of diisodecyl adipate (CAS No. 27178-16-1) was
tested at concentrations of 3, 10 and 30 % w/v in acetone in a Local
Lymph Node Assay according to OECD Guideline 429 (Noakes, 1999). Each
dose level was tested in groups of four mice of the CBA/Ca/Ola/Hsd
strain. Approx. 25 µL of the test substance was applied to the dorsal
surface of each ear. A vehicle control group was treated with acetone
alone. The procedure was repeated daily for 3 consecutive days. 3 days
after the third application, all animals were injected with 3H-methyl
thymidine via the tail vein. Approximately 5 hours later, the animals
were killed and single cell suspensions of the auricular lymph nodes
were measured using a Liquid Scintillation Counter. The isotope
incorporation was less than 3-fold at all tested concentrations. Based
on the study results no sensitising potential of diisodeyl adipate was
In a study according to OECD guideline 406, the skin sensitisation
potential of Bis(2-octyldodecyl) azelate (CAS 897626-46-9) was
investigated in female guinea pigs according to the non-adjuvant Buehler
method (Richeux, 2013).
Based on a primary irritation test, the induction treatment of the main
assay was performed with the neat test substance (100%). In the
induction phase, the test material was applied to the shorn skin of the
scapular zone of 20 animals using an occlusive dressing. During
induction, three consecutive topical applications for a period of 6 h
were performed at intervals of 7 days. A group of 10 animals served as
controls and received paraffin oil. After a 14-day rest period, the
challenge exposure was performed in control and treated animals. The
test substance was applied to the shorn skin of the left flank of the
animals for 6 h and skin reactions were evaluated 24 and 48 h after
application. Accordingly, a patch without test material was applied to
the animals’ right flanks. No positive skin reactions were observed in
any of the animals of the test group and the control group. During the
study no mortality occurred and no effects on body weight gain were
observed. The sensitivity of the test species was confirmed with the
positive control substance α-Hexylcinnamaldehyde (CAS 101-86-0)
routinously tested in this laboratory (data of the three latest positive
control tests are provided in the study report).
Based on these results, Bis(2-octyldodecyl) azelate was found to be a
not sensitising in guinea pigs under the conditions of the non-adjuvant
A human volunteer study was performed under GCP conditions to assess the
sensitising potential of diisopropyl sebacate (CAS No. 7491-02-3) using
the Marzulli and Maibach method (Cathalot, 2002). As induction treatment
the back skin of 51 volunteers was exposed to the undiluted test
substance for 48 hours under occlusive conditions three times a week for
three weeks. After a two week recovery period, a challenge exposure was
performed under an occlusive dressing for 48 h either on the same site
as the induction or another site that had never had contact with the
test substance. None of the 51 persons showed any sensitisation to the
test material and only one showed slight skin irritation (+) at Day 9 of
induction. Thus, the test material at 100% when applied to the human
skin was not irritating and not sensitising.
The skin sensitising potential of bis(2-ethylhexyl) azelate (CAS
103-24-2) was investigated in a Local Lymph Node Assay (LLNA) in mice
according to OECD guideline 429 and in compliance with GLP (Bradshaw,
Based on a range-finding test in one female CBA/CaOlaHsd mouse, the
undiluted test substance (100%) and concentrations of 25% and 50% (v/v)
in acetone/olive oil (4:1 v/v) were selected for the treatment of mice
in the main study. In this experiment, 4 female CBA/CaOlaHsd mice per
test group were treated with the test substance or vehicle alone,
respectively. The test substance or the vehicle was applied on the
external surface of each ear (25 µL/ear) for three consecutive days.
Five days after the first topical application, the cell proliferation of
pooled lymph nodes per group was measured by incorporation of ³H-methyl
thymidine and expressed as the amount of radioactive disintegration per
minute (DPM). The DPM/lymph node for each test group was 5244.83,
5178.42 and 8048.58 at concentrations of 25%, 50% and 100% of the test
substance, respectively. For the control group, a DPM/lymph node of
1553.82 was determined. Based on these results, stimulation indices of
3.38, 3.33 and 5.18 were calculated for treatment concentrations of 25%,
50% and 100%, respectively. No local or systemic toxicity and no effects
on body weights were observed. The historical positive control substance
α-Hexylcinnamaldehyde (25% in acetone:olive oil (4:1 v/v)) produced a
stimulation index (SI) of 5.76, thus meeting the reliability criteria
for the LLNA (SI > 3).
As no structural analogue showed sensitising potential and the test
substance is unlikely to penetrate the skin (0.00001 mg/cm²/event, QSAR,
Danish EPA, 2010) the result of the above mentioned LLNA is regarded as
Conclusions for skin sensitisation
No studies assessing the skin sensitising properties of Diisodecyl
azelate (CAS 28472-97-1) are available.
However, two local lymph node assays (LLNA) were performed with
the structurally related substances diisodecyl adipate (CAS 27178-16-1)
andbis(2-ethylhexyl) azelate (CAS 103-24-2), in which no skin
sensitisation was observed (Noakes, 1999; Bradshaw, 2012). A Buehler
test was performed with the analogue substance Nonanedioic acid,
1,9-bis(2-octyldodecyl) ester (CAS 897626-46-9), in which no skin
sensitisation was induced (Richeux, 2013). The results of a human patch
test (epicutaneous test) performed in 51 human volunteers with the
analogue substance Diisopropyl sebacate (CAS 7491-02-3) showed that the
substance had no skin sensitising effects (Cathalot, 2002).
Taking all the available data into consideration, Diisodecyl
azelate (CAS 28472-97-1) is considered not to be a skin sensitiser.
Based on read-across substances following an analogue approach and based
on a weight of evidence approach, the available data on the skin
sensitisation potential do not meet the classification criteria
according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are
therefore conclusive but not sufficient for classification.
There are no data available on respiratory sensitisation.
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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