3-p-cumenyl-2-methylpropionaldehyde

Endpoint summary

Description of key information

Skin sensitisation: Based on the results of LLNA study the Cyclamen Aldehyde has shown an EC3 value of 22.3% and is classified as a weak sensitiser.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

not specified

GLP compliance:

not specified

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source:
Harlan Olac, Bicester, Oxfordshire, UK)

- Age at study initiation:
6–12 weeks old

- Housing:
Mice were housed under standard conditions

- Diet (e.g. ad libitum):
Food was available ad libitum.

- Water (e.g. ad libitum):
tap water was available ad libitum.

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

Cyclamen aldehyde (100% assumed)

No. of animals per dose:

4

Details on study design:

The LLNA was performed according to the standard protocol. Groups of mice (n = 4) were exposed topically on the dorsum of both ears to 25 µl of various concentrations of the test aldehyde, or to the same volume of vehicle (AOO) alone, daily for 3 consecutive days.

5 days after the initiation of exposure, all mice were injected intravenously via the tail vein with 20 µCi of [3H]methyl thymidine (3H-TdR; specific activity 2 Ci.mmol -1; Amersham International, Amersham, UK) in 250 µl of phosphate buffered saline (PBS). 5 h later, mice were killed and the draining
auricular lymph nodes were excised and pooled for each experimental group. A single-cell suspension of lymph node cells (LNC) was prepared by gentle mechanical disaggregation through a 200-mesh stainless-steel gauze. Cells were washed twice with an excess of PBS and precipitated in 5% trichloroacetic acid (TCA) at 4 °C. Approximately 12 h later, pellets were resuspended in 1 ml of 5% TCA and transferred to 10 ml of scintillation fluid (Optiphase ‘‘Hisafe3’’, Wallac, Turku, Finland). Incorporation of 3H-TdR was measured by ß-scintillation counting as disintegration per minute (dpm) per node for each experimental group. In each case, a stimulation index (SI) relative to the concurrent vehicle treated control value was derived.

Positive control substance(s):

not specified

Parameter:

SI

Value:

5.16

Test group / Remarks:

50% solution

Parameter:

other: disintegrations per minute (DPM)

Value:

750

Test group / Remarks:

50 % solution

Parameter:

SI

Value:

1.4

Test group / Remarks:

1% solution

Parameter:

SI

Value:

1.34

Test group / Remarks:

2.5% solution

Parameter:

SI

Value:

1.84

Test group / Remarks:

10% solution

Parameter:

SI

Value:

3.26

Test group / Remarks:

25% solution

Parameter:

EC3

Remarks:

%

Value:

22.3

Results for Cyclamen Aldehyde

Concentration %	DPM /node	SI
0	145	1
0.1	-	-
0.5	-	-
1	204	1.4
2.5	195	1.34
5	-	-
10	267	1.84
25	47	3.26
50	750	5.16

derived EC3 = 22.3%

Discussion:

The murine local lymph node assay (LLNA) assesses skin sensitization potential as a function of proliferative responses induced in lymph nodes draining the site of topical exposure to test chemical. It has been shown that interpolation of LLNA dose-response data to define the concentration of test chemical required to induce a 3-fold stimulation of proliferation (EC3) offers the prospect of a quantitative index of the relative potency of a contact allergen. Initial studies have demonstrated that there exists a strong (inverse) correlation between EC3 values and contact allergenic potency in humans. Thus, materials with a low EC3 value were more potent contact allergens in humans. However, it is necessary to examine a wide range of allergens to demonstrate that such correlations are generally true.

Thus, in the present study, 10 aldehydes (including Cyclamen Aldehyde) of varying degrees of allergenicity in man were evaluated in the LLNA and their EC3 values derived. Formaldehyde was regarded as the strongest allergen in man and also had the lowest EC3 value, 0.35% (equivalent to 0.93% formalin).

In contrast, the extremely weak allergen vanillin and the non-sensitizer ethyl vanillin both had EC3 values of >50%. For the remaining 7 aldehydes, there was a close similarity between what is judged to be their rank order of allergenicity in humans and EC3 values derived from analysis of LLNA data. These results support further the utility of EC3 determinations in the LLNA as a measure of the relative potency of a contact allergen.

In conclusion, the results presented in this paper demonstrate further that the LLNA provides quantitative information on skin sensitizing potency which is predictive of allergenic potency in humans. Such data promises to be a valuable tool for hazard characterization and for risk assessment.

Based on the results of this study the Cyclamen Aldehyde is classified as a weak sensitiser (Cat 1B)

Interpretation of results:

Category 1B (indication of skin sensitising potential) based on GHS criteria

Remarks:

Criteria used for interpretation of results: EU

Conclusions:

Under the conditions of this paper, the test item was found to be a skin weak sensitiser. The EC3 value of 22.3 % (w/v) was determined.
Based on the results of this study the Cyclamen Aldehyde is classified as a weak sensitiser Category 1B, based on GHS criteria.

Executive summary:

The study was performed according to the local lymph node assay method to assess the skin sensitisation potential of the test item in the CBA/Ca strain mouse following topical application to the dorsal surface of the ear. The test item was tested at concentrations of: 0.1%, 0.5%, 1%, 2.5%, 5%, 10%, 25% and 50% (w/v) in acetone/olive oil (4:1) and with a 0% vehicle control group. The SI values calculated for the test item concentrations 0.1%, 0.5%, 1%, 2.5%, 5%, 10%, 25% and 50% were 0, 0, 1.4, 1.34, 0, 1.84, 3.26, and 5.16 respectively. The results show that the test item elicited an SI ≥ 3 and resulted in a calculated EC3 value of 22.3 % (w/v). Under the conditions of this study, the test item was found to be a weak skin sensitiser (Cat 1B) based on GHS classification.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The results presented in the skin sensitisation paper demonstrate further that the LLNA provides quantitative information on skin sensitising potency which is predictive of allergenic potency in humans. Such data promises to be a valuable tool for hazard characterization and for risk assessment.

Based on the results of this study the Cyclamen Aldehyde is classified as a weak sensitiser Category 1B, based on GHS criteria.

Justification for selection of skin sensitisation endpoint:
the LLNA provides quantitative information on skin sensitising potency which is predictive of allergenic potency in humans.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the results of this study the Cyclamen Aldehyde has shown an EC3 value of 22.3% and is classified as a weak sensitiser Category 1B, based on GHS criteria.