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Description of key information

Capacity for allergic sensitization of the test chemical was determined by the intradermal test With Freund's Complete Adjuvant (FCAT) on Guinea pigs.

Challenging epicutaneous tests with non toxic alcoholic solutions of test chemical, 3 and 5 weeks after the first intradermal injection were positive in 7 out 7 animals with the 10% solution, (the highest non irritant concentration), in 4 out of 7 animals with the 3% solution and in 2 out of 7 animals with the 1% solution.

Therefore, the test chemical was considered to be one of the moderate to strong intradermal sensitizers for the guinea pig in the FCAT and hence classified as skin sensitiser in category 1 as per CLP classification criteria.

A mouse local lymphnode assay(LLNA) was performed to determine the sensitization potential of the test chemical. The study was performed as per OECD 429 Guidelines.

The EC3 value for the test chemical was 21. According to classification scheme, the test chemical can be considered to be weakly sensitizing to the skin of mice.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Justification for type of information:
Data is from experimental study report
Qualifier:
according to
Guideline:
other: Freund's Complete Adjuvant [FCAT] test
Principles of method if other than guideline:
Capacity for allergic sensitization determined by the intradermal test With Freund's Complete Adjuvant [FCAT] test on Guinea pigs.
GLP compliance:
not specified
Type of study:
Freund's complete adjuvant test
Justification for non-LLNA method:
not specified
Species:
guinea pig
Strain:
not specified
Sex:
not specified
Details on test animals and environmental conditions:
No data available
Route:
intradermal
Vehicle:
other: 0.05 ml of FCA
Adequacy of induction:
not specified
Route:
intradermal
Vehicle:
other: 50% FCA
Concentration / amount:
0.05 ml of the compound (undiluted, diluted or suspended) (total dose approx. 250 mg)
Day(s)/duration:
0, 2, 4, 7 and 9 days
Adequacy of induction:
not specified
No.:
#1
Route:
epicutaneous, open
Vehicle:
other: 0.05 ml of FCA
Concentration / amount:
tests were performed by applying 0.025 ml of each test concentration.
Day(s)/duration:
21 and 35 days
Adequacy of challenge:
other: primary non irritant solution
No. of animals per dose:
7 animals
Details on study design:
RANGE FINDING TESTS:

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 5 intradermal injections
- Exposure period: 0, 2, 4, 7 and 9 days
- Test groups: 7 guinea pigs
- Control group: Yes
- Site: Neck
- Frequency of applications: No data available
- Duration: No data available
- Concentrations: 0.025 ml

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 21 and 35
- Exposure period: No data available
- Test groups: 7 guinea pigs
- Control group: Yes
- Site: Neck (Skin area measuring 2 cm2)
- Concentrations: 0.025 ml
- Evaluation (hr after challenge): 24, 48 and 72 hours

Positive control substance(s):
not specified
Key result
Reading:
other: Challenge
Hours after challenge:
72
Group:
test group
Dose level:
10% solution
No. with + reactions:
7
Total no. in group:
7
Clinical observations:
signs of dermal reactions observed
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
other: Challenge
Hours after challenge:
72
Group:
test group
Dose level:
3% solution
No. with + reactions:
4
Total no. in group:
7
Clinical observations:
signs of dermal reactions observed
Remarks on result:
positive indication of skin sensitisation
Key result
Reading:
other: Challenge
Hours after challenge:
72
Group:
test group
Dose level:
1% solution
No. with + reactions:
2
Total no. in group:
7
Clinical observations:
signs of dermal reactions observed
Remarks on result:
positive indication of skin sensitisation

Induction

Challenge

Sensatization rate

Testing concentration

3%

Pos./total

1%

Pos./total

5 intradermal injections of a 0.1 ml of a 50% emulsion in FREUND’S COMPLETE ADJUVANTS

Epicutaneously with primary non irritant solution

 4/7

2/7

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
Challenging epicutaneous tests with non toxic alcoholic solutions of test chemical, 3 and 5 weeks after the first intradermal injection were positive in 7 out 7 animals with the 10% solution, (the highest non irritant concentration), in 4 out of 7 animals with the 3% solution and in 2 out of 7 animals with the 1% solution.
Therefore,the test chemical was considered to be one of the moderate to strong intradermal sensitizers for the guinea pig in the FCAT and hence classified as skin sensitiser in category 1 as per CLP classification criteria.
Executive summary:

Capacity for allergic sensitization of the test chemical was determined by the intradermal test With Freund's Complete Adjuvant (Fact) on Guinea pigs.

0.05 ml of the compound (undiluted, diluted or suspended) was mixed with the same volume of FCA were injected intradermally into the neck on days 0,2,4,7 and 9 (total dose approx.250 mg).The experimental animals and controls, treated with 0.05 ml of FCA only, were tested epicutaneously on days 21 and 35.These tests were performed by applying 0.025 ml of each test concentration to skin areas measuring 2 cm2. The reactions were read after 24, 48, and 72 hours.

Challenging epicutaneous tests with non toxic alcoholic solutions of test chemical, 3 and 5 weeks after the first intradermal injection were positive in 7 out 7 animals with the 10% solution, (the highest non irritant concentration), in 4 out of 7 animals with the 3% solution and in 2 out of 7 animals with the 1% solution.

Therefore,the test chemical was considered to be one of the moderate to strong intradermal sensitizers for the guinea pig in the FCAT and hence classified as skin sensitiser in category 1 as per CLP classification criteria.

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Justification for type of information:
data is from peer reviewed journals
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Principles of method if other than guideline:
To evaluate the potential of the test chemical for inducing allergic contact dermatitis
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
CBA
Remarks:
q
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
Source: No data
Age at study initiation: 7-12 weeks

ENVIRONMENTAL CONDITIONS: No data
Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
25 µl of 10,25, 50 and90% test chemical in AOO
No. of animals per dose:
groups of female mice (number not specified)
Details on study design:
Details on study design

Pre –screen tests : No data

MAIN STUDY

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response:
A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). Dose response data were used to measure the relative skin sensitization potency of all of the chemicals that were positive. When the LLNA dose-response curve included concentrations that induced at least one SI greater than 3 and one SI less than 3, EC3 values were calculated by linear interpolation. For chemicals that induced an SI greater than or equal to 3 at all concentrations tested, an EC3 value was extrapolated from the two lowest doses used. For this extrapolation method to work, a dose response should be evident. The relative sensitizing potencies of the chemical allergens were categorized via a recently proposed arbitrary classification scheme.

TREATMENT PREPARATION AND ADMINISTRATION: groups of CBA female mice (7–12 weeks of age) were exposed topically on the dorsum of both ears to 25 µL of test material or to an equal volume of the relevant vehicle alone. Treatment was performed daily for 3 consecutive days. Five days after the initiation of exposure, all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 hours later, and the draining auricular lymph nodes were excised and pooled for each experimental group or each individual animal. The incorporation of tritiated thymidine measured by beta scintillation counting was reported in disintegrations per minute (dpm). A stimulation index (SI) was calculated for each chemical-treated group as the ratio of the dpm of the treated group (or mean dpm when individual animals were assessed) to the dpm or mean dpm of the concurrent vehicle control group.
Positive control substance(s):
not specified
Statistics:
A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3). Dose response data were used to measure the relative skin sensitization potency of all of the chemicals that were positive. When the LLNA dose-response curve included concentrations that induced at least one SI greater than 3 and one SI less than 3, EC3 values were calculated by linear interpolation.
Key result
Parameter:
EC3
Value:
21
Test group / Remarks:
test group
Remarks on result:
other: positive sensitizer
Cellular proliferation data / Observations:
The EC3 value for the test chemical was 21. According to classification scheme, the test chemical can be considered to be weakly sensitizing to the skin of mice.

Table: Chemical Structures, Molecular Weights, LLNA Data, Potency Categorizations, and Reaction Mechanistic Domains

CAS

Name of the test chemical

Vehicle

LLNA%

LLNA%

LLNA%

LLNA%

LLNA SI

LLNA SI

LLNA SI

LLNA SI

LLNA EC3

Relative Potency

104-54-1

Cinnamic alcohol

AOO

10

25

50

90

1.8

3.5

3.9

5.7

21

Weak sensitizer

AOO- Acetone and Olive oil (4:1); LLNA – Local lymph node assay (LLNA% = weight per volume concentration); EC3 – Mathematically estimated concentration of the test chemical necessary to induce a threefold stimulation index; Pro/Pre – Not direct-acting electrophiles but able to be converted to electrophiles by well-established transformations (abiotic or metabolic), MA –Michaels acceptor

**value is estimated

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Conclusions:
The EC3 value for the test chemical was 21. According to classification scheme, the test chemical can be considered to be weakly sensitizing to the skin of mice.
Executive summary:

The dermal sensitization potential ofthe test chemical was evaluated in a mouse local lymphnode assay(LLNA). The study was performed as per OECD 429 Guidelines. Groups of female CBA mice (7-12 weeks of age) were exposed topically on the dorsum of both ears to 25 µl of 10,25, 50 and90% test chemical in AOO or to an equal volume of relevant vehicle only. Treatment was performed daily for 3 consecutive days.Five days after the initiation of exposure, all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 hours later, and the draining auricular lymph nodes were excised and pooled for each experimental group or each individual animal. The incorporation of tritiated thymidine measured by beta scintillation counting was reported in disintegrations per minute (dpm). A stimulation index (SI) was calculated for each chemical-treated group as the ratio of the dpm of the treated group (or mean dpm when individual animals were assessed) to the dpm or mean dpm of the concurrent vehicle control group.The approach to estimation of the relative skin sensitization potential was based on the mathematical estimation of the concentration of chemical necessary to obtain a threshold positive response (SI = 3); this is termed as the EC3 value.A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3).The EC3 value for the test chemical was 21. According to classification scheme, the test chemical can be considered to be weakly sensitizing to the skin of mice.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

Various studies have been reviewed to determine the allergic potential of the test chemical in living organisms. These include in vivo experimental studies performed on guinea pigs, rabbits as well as mice. The studies are summarized below:

Capacity for allergic sensitization of the test chemical was determined by the intradermal test With Freund's Complete Adjuvant (FCAT) on Guinea pigs.

0.05 ml of the compound (undiluted, diluted or suspended) was mixed with the same volume of FCA were injected intradermally into the neck on days 0,2,4,7 and 9 (total dose approx.250 mg).The experimental animals and controls, treated with 0.05 ml of FCA only, were tested epicutaneously on days 21 and 35.These tests were performed by applying 0.025 ml of each test concentration to skin areas measuring 2 cm2. The reactions were read after 24, 48, and 72 hours.

Challenging epicutaneous tests with non toxic alcoholic solutions of test chemical, 3 and 5 weeks after the first intradermal injection were positive in 7 out 7 animals with the 10% solution, (the highest non irritant concentration), in 4 out of 7 animals with the 3% solution and in 2 out of 7 animals with the 1% solution.

Therefore, the test chemical was considered to be one of the moderate to strong intradermal sensitizers for the guinea pig in the FCAT and hence classified as skin sensitiser in category 1 as per CLP classification criteria.

This is supported by a Buehler delayed hypersensitivity test performed to determine allergic potential of the test chemical in guinea pigs.

Induction was via a 6-hour closed patch application with 10% test chemical in 80% ethanol/water on days 1, 7 and 14. Ten to fourteen days after the last induction patch, challenge application was by a 6-hour occluded patch with 1%, 3% and 10% test chemical in acetone. Reactions were read at 24 and 48 h. There

No reactions were noted in the guinea pigs tested with 1% test chemical in acetone; 1/10 reactions were observed at 3%; 2/10 reactions were observed at 10%. Sensitization reactions were observed at all dose levels over 1%. Hence, the test chemical was considered to be sensitizing to the guinea pig skin.

This guinea pig study is supported by a mouse local lymphnode assay(LLNA) performed to determine the sensitization potential of the test chemical. The study was performed as per OECD 429 Guidelines. Groups of female CBA mice (7-12 weeks of age) were exposed topically on the dorsum of both ears to 25 µl of 10,25, 50 and90% test chemical in AOO or to an equal volume of relevant vehicle only. Treatment was performed daily for 3 consecutive days.Five days after the initiation of exposure, all mice were injected via the tail vein with 250 µL of phosphate buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 hours later, and the draining auricular lymph nodes were excised and pooled for each experimental group or each individual animal. The incorporation of tritiated thymidine measured by beta scintillation counting was reported in disintegrations per minute (dpm). A stimulation index (SI) was calculated for each chemical-treated group as the ratio of the dpm of the treated group (or mean dpm when individual animals were assessed) to the dpm or mean dpm of the concurrent vehicle control group.The approach to estimation of the relative skin sensitization potential was based on the mathematical estimation of the concentration of chemical necessary to obtain a threshold positive response (SI = 3); this is termed as the EC3 value.A substance was classified as a skin sensitizer if it induced a threefold or greater increase in local lymph node proliferative activity at one or more test concentrations when compared with concurrent vehicle-treated controls (SI≥3).The EC3 value for the test chemical was 21. According to classification scheme, the test chemical can be considered to be weakly sensitizing to the skin of mice.

The results of LLNA assay are supported by a Guinea pig maximisation test conducted in Himalayan white-spotted guinea pigs (male and female) to determine the skin sensitization potential of the test chemical.

During induction, on day 0, the animals were injected intradermally with 0.1 ml of a 5% solution of the compound tested, with 0.1 ml of a 5 % emulsion of the same compound in Freund's complete adjuvant (FCA) and with 0.1 ml of FCA alone. On day 8 the animals were induced epicutaneously with 250 mf of 25% test compound in dissolved in petrolatum on clipped skin area of the neck under occlusion for 2 days. On day 21, animals were challenged with the compound at a subirritant concentration in petrolatum was applied to the flank for 24 h. The reactions were read 24 and 48 h after removing the patch.

Signs of contact sensitization were observed in the guinea pigs after challenge exposure.

Hence, the test chemical can be considered to be sensitizing to skin.

These results are further supported by Magnusson–Kligman maximization test performed on Dunkin–Hartley guinea pigs to determine the sensitisation potential of the test chemical. The study was conducted on male and female albino Dunkin–Hartley guinea pigs (10/group) with an average initial weight of approximately 320 g.

Induction consisted of two stages, intradermal injection followed one week later by a 48- hour occluded patch application. A total of six intradermal injections were administered. They comprised: two injections of 0.1ml of 50% Freunds complete adjuvant in 0.01% DOBS saline; two injections of 0.1ml of a 0.35% solution of test chemical in 0.01% DOBS saline; two injections of 0.1 ml of a suspension of 0.35% test chemical in 0.01% DOBS saline mixed (50:50) with Freund's Complete Adjuvant.

The topical induction concentration was 100%. Challenge concentration was 40% in acetone/PEG. Challenge application was made 13–14 days after thetopical induction application. The guinea pigs were challenged on the shaved flank by an occluded 24-hour patch. One week after the first challenge a second challenge, application was made on the opposite flank and a third challenge treatment was carried out 7 days after that on the alternate flank. Reactions were read at 24 and 48 h after patch removal. At the first challenge only, the challenge treatment was applied to four treated controls that had been given a mock induction treatment. At all three challenge applications, four previously untreated control animals received the challenge treatment. A total of 2/10 sensitization reactions were observed after the first challenge; n reactions were observed after the second challenge; 8/

10 sensitization reactions were observed after the third challenge.

Thus, from the study it can be concluded that test chemical induces a skin sensitisation effects in guinea pigs in the Magnusson-Kligman maximization test and hence classified as skin sensitiser in category 1 as per CLP classification criteria.

In a similar study, albino female Ssc:AL guinea pigs (20/group) weighing 250–350 g were used to determine the sensitization potential of the test chemical.

Induction was via intradermal injection with 5% test chemical in propylene glycol and Freund's Complete Adjuvant in saline on day 0 and a topical induction patch with 25% test chemical in propylene glycol on day 7. Ten percent (10%) sodium lauryl sulfate was massaged into the skin 24 h before the topical induction patch. Munktel filter paper mounted on Leucoflex was used for the topical induction patch. On day 21, guinea pigs were challenged on the clipped, shaved flank with a 24-hour occluded patch using Finn Chambers on Scanpor. Reactions were read 72 h after patch application.

To evaluate cross-sensitization, animals were also challenged with cinnamic aldehyde and cinnamic acid. One sensitization reaction was observed with 8 mg/ml test chemical in ethanol; no cross-reactions were observed at this dose level. Nine sensitization reactions were observed at 120 mg/ml in ethanol; 15 guinea pigs cross-reacted to cinnamic aldehyde at this dose level; no cross-reactions were observed with cinnamic acid. Thus, from the study it can be concluded that the test chemical induces a skin sensitisation effect in guinea pigs in the Magnusson-Kligman maximization test.

These results are further supported by a Guinea pig maximization test performed to determine the sensitisation potential of the test chemical. The material was tested at a concentration of 10% (vehicle not reported). Strong sensitization effects were produced. Thus, from the study it can be concluded that the test chemical was a skin sensitizer and hence classified as skin sensitiser in category 1 as per CLP classification criteria.

Buehler delayed hypersensitivity test was also performed to determine allergic potential of the test chemical in guinea pigs.

Induction exposure consisted of three 6-hour closed patch applications to the same clipped site on the dorsal surface with 30% test chemical (vehicle not reported).

Induction applications were made once a week for 3 weeks. Following a 10–14 day rest, the guinea pigs were challenged with 10% test chemical (vehicle not reported). Challenge application was a 6-hour occluded patch at a naive skin site. Ten naive control animals were challenged at the same time in an identical manner.

Reactions were read at 24 and 48 h after patch removal. Sensitization was observed in 50% of the animals. Hence, the test chemical was considered to be sensitizing to skin.

These results are lent support by a Closed Epicutaneous Test (CET) performed to evaluate the dermal sensitization potential of the test chemical. 6 guinea pigs/group were treated with the test chemical for the induction and challenge exposure.

Induction consisted of six 48-hour closed patch applications on the nape using Torii's patch plaster and adhesive tape. Induction applications were made three times a week for two weeks with 10% test chemical.

On day 28, the animals were challenged with 10% test chemical in acetone. Challenge application was a 48- hour closed patch on the clipped and shaved flank using Finn Chambers and adhesive tape. Reactions were read at patch removal and 24 and 48 h after patch removal. 2/6 positive reactions were observed. Hence, the test chemical can be considered to be sensitizing to skin.

The above results are also supported by a FREUND'S COMPLETE ADJUVANT (FCAT) test conducted in Himalayan white-spotted guinea pigs (male and female) to determine the skin sensitization potential of the test chemical.

In this test, doses of 0.05 ml of the undiluted compound mixed with the same volume of FCA were injected intradermally into the neck on days 0, 2, 4, 7, and 9 (total dose 250 mg). The control animals were similarly treated with 5 x 0.05 ml of FCA alone. On day 21, animals were challenged with the compound at a subirritant concentration in petrolatum was applied to the flank for 24 h. The reactions were read 24 and 48 h after removing the patch.

Signs of skin reactions were observed during 48 hours observation period. Thus the test chemical was considered to be sensitizing to the skin of Himalayan white-spotted guinea pigs.

The results of the in vivo studies on various test animals give a clear indication that the test chemical is indeed sensitizing to skin. Hence, it can be classified under the category “Skin Sensitizer 1” as per CLP Regulation.

Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

The results of the in vivo studies on various test animals give a clear indication that the test chemical is indeed sensitizing to skin. Hence, it can be classified under the category “Skin Sensitizer 1” as per CLP Regulation.