Dimethyl (p-methoxybenzylidene)malonate

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl (p-methoxybenzylidene)malonate

EC Number:

231-185-8

EC Name:

Dimethyl (p-methoxybenzylidene)malonate

Cas Number:

7443-25-6

Molecular formula:

C13H14O5

IUPAC Name:

1,3-dimethyl 2-[(4-methoxyphenyl)methylidene]propanedioate

Test material form:

solid

Test animals

Species:

rabbit

Strain:

New Zealand White

Remarks:

SPF

Details on test animals or test system and environmental conditions:

Age at start of treatment: 14-15 weeks (male), 13-14 weeks (females)
Body weights at start of treatment: 2.3 - 2.9 kg
Identification: By unique cage number and corresponding ear number.
Acclimatization: Six days under laboratory conditions after health examination. Only animals without any visual signs of illness were used fior the study.
Allocation: Male No. 88, Female Nos. 89 and 90

Test system

Type of coverage:

semiocclusive

Preparation of test site:

clipped

Vehicle:

water

Controls:

not required

Amount / concentration applied:

The test item was administered at 0.5 g/animal, the dose specified in the test guidelines for a solid test item.

Duration of treatment / exposure:

4 hours

Observation period:

The skin irritation was assessed according to the numerical scoring system listed in the EEC Commission Directive 92/69/EEC, July 31, 1992 at approximately 1, 24, 48 and 72 hours, after the removal of the dressing, gauze patch and test item.

Number of animals:

1 male and 2 females

Details on study design:

TEST ITEM PREPARATION:
0.5 g (per animal) of the test item was weighed as delivered by the sponsor and then moistened with bi-distilled water before application. According to Directive 92/69 EEC, B.4 and OECD Guidelines 404, a substance needs not to be tested if the pH-value is less than 2 or greater than 11.5, owing to its predictable corrosive properties. Prior to the application the pH of the test item was determined at a concentration of 1 % in water with pH-Test-Strip (E. Merck, D-64271 Darmstadt / Germany). The pH was found to be 6.

TREATMENT:
Four days before treatment, the left flank was clipped with an electric clipper, exposing an area of approximately 100 cm² (10 cm x 10 cm). The skin of the animals was examined one day before treatment, and regrown fur of all animals was again clipped. Animals with overt signs of skin injury or marked irritation which may have interfered with the interpretation of the results were not used in the test. On the day of treatment, 0.5 g of test item was placed on a surgical gauze patch (ca. 2.5 cm x 2.5 cm). This gauze patch was applied to approximately 6 cm² of the intact skin of the clipped area. The patch was covered with a semi-occlusive dressing [Isoelast Heftpflaster Acryl 8 x 75 cm]. The dressing was wrapped around the abdomen and anchored with tape. The duration of treatment was 4 hours. Then the dressing was removed and the skin was flushed with lukewarm tap water to clean the application site so that any reactions (erythema) were clearly visible at that time.

OBSERVATIONS:

Viability/Mortality: Daily from delivery of the animals to the termination of test.
Clinical signs: Daily from delivery of the animals to the termination of test.
Body weights: At start of acclimatization, on the day of application and at termination of observation.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

other: cumulative (erythema and oedema score)

Basis:

mean

Time point:

other: 1 h

Score:

1.33

Max. score:

2

Reversibility:

not specified

Results 2

Irritation parameter:

other: cumulative (erythema and oedema score)

Basis:

mean

Time point:

24 h

Score:

0.67

Max. score:

1

Reversibility:

not specified

Results 3

Irritation parameter:

other: cumulative (erythema and oedema score)

Basis:

mean

Time point:

48 h

Score:

0

Max. score:

0

Reversibility:

not specified

Results 4

Irritation parameter:

other: cumulative (erythema and oedema score)

Basis:

mean

Time point:

72 h

Score:

0

Max. score:

0

Reversibility:

not specified

Results 5

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #1, #2, #3

Time point:

24/48/72 h

Score:

0.22

Max. score:

4

Reversibility:

fully reversible within: 48 h

Remarks on result:

no indication of irritation

Results 6

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #1, #2, #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

other: not applicable since no effect

Remarks on result:

no indication of irritation

Any other information on results incl. tables

VIABILITY/MORTALITY/CLINICAL SIGNS:

No clinical signs of systemic toxicity were observed in the animals during the study and no mortality occurred.

IRRITATION:

Application of the test item to healthy intact rabbit skin resulted in a primary irritation score of 0.22.

Local signs (mean values from 24 to 72 hours) consisted of grade 0.22 erythema and grade 0.00 oedema.

A very slight erythema was observed in all animals at the 1 -hour observation before disappearing by 24 hours (one animal) or 48 hours (two animals). A very slight oedema was noted in one animal at the 1 -hour reading.

COLORATION:

No staining by the test item of the treated skin was observed.

CORROSION:

No irreversible alterations of the treated skin were observed nor were corrosive effects evident on the skin.

BODY WEIGHTS:

The body weights of all rabbits were considered to be within the normal range of variability.

Applicant's summary and conclusion

Interpretation of results:

other: not irritating

Conclusions:

Based upon the referred classification criteria (EEC Commission Directive 93/21/EEC of April 27, 1993 and Regulation (EC) No. 1272/2008 (CLP)), the test item is considered to be "not irritating" to rabbit skin.

Executive summary:

The primary skin irritation potential of the test item was investigated by topical semi-occlusive application of 0.5 g to 6 cm² intact left flank of each of three young adult New Zealand White rabbits. The duration of treatment was four hours. The scoring of skin reactions was performed 1, 24, 48 and 72 hours after removal of the dressing. The scores of each animal at the following reading times (24, 48, 72 hours) were used in calculating the respective mean values for each type of lesion.

The primary irritation score was calculated by totaling the individual cumulative scores at 24, 48 and 72 hours and then dividing by the number of data points. The primary irritation score was 0.22 (max. 8.0).

Local signs (mean values from 24 to 72 hours) consisted of grade 0.22 erythema and grade 0.00 oedema.

A very slight erythema was observed in all animals at the 1 -hour observation before disappearing by 24 hours (one animal) or 48 hours (two animals). A very slight oedema was noted in one animal at the 1 -hour reading.

The test item caused no staining of the treated skin.

No corrosive effects were noted on the treated skin of any animal at any measuring interval.

Based upon the referred classification criteria (EEC Commission Directive 93/21/EEC of April 27, 1993 and Regulation (EC) No. 1272/2008 (CLP)), the test item is considered to be "not irritating" to rabbit skin