Phenylacetaldehyde

Skin sensitisation

Administrative data

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:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

publication

Title:

Human potency predictions for aldehydes using the local lymph node assay

Author:

Basketter et al.

Year:

2001

Bibliographic source:

Contact Dermatitis, Vol. 45, pp. 89-94

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

no

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Phenylacetaldehyde

EC Number:

204-574-5

EC Name:

Phenylacetaldehyde

Cas Number:

122-78-1

Molecular formula:

C8H8O

IUPAC Name:

2-phenylacetaldehyde

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Age at study initiation: 6-12 weeks
- Housing: under standard conditions
- Diet: ad libitum
- Water: tap water, ad libitum
- Acclimation period: 5 days

No further data

Study design: in vivo (LLNA)

Vehicle:

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

Concentration:

Test substance and positive control: 1, 2.5, 5, 10, 25 and 50%

No. of animals per dose:

4

Details on study design:

ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: 3H-methyl thymidine incorporation determined by ß-scintillation
- Criteria used to consider a positive response: A stimulation index (SI) relative to the concurrent vehicle treated control value was calculated for each group. The criterion for a positve response is that one or more concentrations of the test substance should elicit a 3-fold or greater increase in isotope incorporation relative to the vehicle control group.

TREATMENT PREPARATION AND ADMINISTRATION: The dorsal surface of both ears was topically treated (25 μL/ear) with the test substance daily for 3 consecutive days. Five days after initiation of exposure an injection of 250 µL phosphate buffered saline (PBS) containing 20 µCi of 3H-methyl thymidine (³HTdR) was made into the tail vein of each experimental mouse. Five hours later, following injection of ³HTdR, the mice were sacrificed and draining auricular lymph nodes were excised and pooled for each experimental group. A single cell suspension was prepared by gentle separation through a 200 mesh stainless steel gauze. The cell suspensions were washed two times with an excess of PBS and precipitated with 5% trichloroacetic acid at 4 °C for 12 h. The pellets were resuspended in 1 mL of 5% trichloroacetic acid and transferred to 10 mL of scintillation fluid.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

The EC3 value was calculated by interpolating between 2 points on the SI axis, one immediately above, and the other immediately below, the SI value of 3. The vehicle-treated control (SI=1) cannot be used for the latter. Where the data points lying immediately above and below the SI value of 3 have the co-ordinates (a, b) and (c, d) respectively, then the EC3 value may be calculated using the following equation: EC3 = c + [(3 - d)/(b - d)] × (a - c)

Results and discussion

Positive control results:

The EC3 value calculated for the positive control was 14.7.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

0.73

Test group / Remarks:

1% (w/v)

Results 2

Key result

Parameter:

SI

Value:

1.76

Test group / Remarks:

2.5% (w/v)

Results 3

Key result

Parameter:

SI

Value:

7.84

Test group / Remarks:

5% (w/v)

Results 4

Key result

Parameter:

SI

Value:

8.76

Test group / Remarks:

10% (w/v)

Results 5

Key result

Parameter:

SI

Value:

18.96

Test group / Remarks:

25% (w/v)

Results 6

Key result

Parameter:

EC3

Value:

3

Results 7

Key result

Parameter:

other: disintegrations per minute (DPM)

Value:

185

Test group / Remarks:

1% (w/v)

Results 8

Key result

Parameter:

other: disintegrations per minute (DPM)

Value:

450

Test group / Remarks:

2.5% (w/v)

Results 9

Key result

Parameter:

other: disintegrations per minute (DPM)

Value:

2 000

Test group / Remarks:

5% (w/v)

Results 10

Key result

Parameter:

other: disintegrations per minute (DPM)

Value:

2 233

Test group / Remarks:

10% (w/v)

Results 11

Key result

Parameter:

other: disintegrations per minute (DPM)

Value:

4 834

Test group / Remarks:

25% (w/v)

Applicant's summary and conclusion

Interpretation of results:

other: Skin Sens Cat 1B is required according to Regulation (EC) No 1272/2008

Conclusions:

Under the conditions of the mouse Local Lymph Node Assay the test substance revealed a SI ≥ 3.0 at concentrations of 5, 10 and 25%. The EC3 value was 3.0%. Therefore, the test substance is considered as a moderate sensitiser.