Diethylbenzene

Skin irritation / corrosion

Administrative data

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD TG-404 and EEC Directive 84/449/EEC, Part B.4 and GLP.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

no

Remarks:

Not specified in report.

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.4 (Acute Toxicity: Dermal Irritation / Corrosion)

Deviations:

no

Remarks:

Not specified in report.

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Diethylbenzene

EC Number:

246-874-9

EC Name:

Diethylbenzene

Cas Number:

25340-17-4

Molecular formula:

C10H14

IUPAC Name:

diethylbenzene

Constituent 2

Reference substance name:

o-diethylbenzene

EC Number:

205-170-1

EC Name:

o-diethylbenzene

Cas Number:

135-01-3

Molecular formula:

C10H14

IUPAC Name:

1.2-diethylbenzene

Details on test material:

IUCLID4 Test substance: as prescribed by 1.1 - 1.4

Dowtherm*J >95% dialkylbenzene
Purity 100%
Appearance: Clear, colorless liquid
ReferenceNo.: Batch 150492

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

Species: Albino Rabbit, New Zealand White, (SPF-Quality)
Rational: Recognised by international guidelines as the recommended test system (e.g. OECD, EEC).
Original Source: Broekman Institute , Someren, The Netherlands.
Selection of animals: Healthy animals, not previously used, were selected prior to treatment. Both flanks of each animal were free of interfering lesions,
irritation or defects.
Total number of animals: 3 female rabbits
Age at start of treatment: Approx. 13 weeks
Body weight at start of treatment: 2266 - 2316 grams
Identification: Ear tag.
Acclimatisation: At least five days before start of treatment under test conditions.

HUSBANDRY
Conditions
Standard Laboratory Conditions: Air-conditioned with 15 air changes per hour and controlled environment with optimal conditions considered as being a temperature of 21°C and a relative humidity of 55%. Fluctuations from these optimal conditions were noted, but were considered not to have affected study integrity. Lighting was 12 hours artificial fluorescent light and 12 hours dark per day.

Accommodation
Individually in labelled cages with perforated floors and equipped with an automatic drinking system (ITL, Bergen, The Netherlands).

Diet
Standard laboratory rabbit diet (LKK-20, pellet diameter 4mm, Hope Farms, Woerden, The Netherlands) approx. 100 gram per day.
Certificates of analysis were examined and retained in the NOTOX archives.

Water
Free access to tap-water diluted with decalcified water.
Certificates of analysis were examined and retained in the NOTOX archives.

Test system

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

0.5 ml undiluted

Duration of treatment / exposure:

4 h

Observation period:

21 days

Number of animals:

3

Details on study design:

Treatment
Approximately 24 hours before treatment, the dorsal fur was shaved with electric clippers, exposing an area of approximately 150 square centimeters (10 cm x 15 cm).

Prior to test substance administration, the animals were physically examined and the shaved area of skin to be treated was normal.

On test day 1, 0.5 ml of the test substance was applied to the intact skin of the shaved area on one flank , using a surgical gauze patch 2x3 cm mounted on Micropore tape (3M, St. Paul, U.S.A.). The contralateral flank was similarly prepared (but without test substance) to act as a procedural control. The dressing was wrapped around the abdomen and secured with an elastic bandage (Coban, 3M, St. Paul, U.S.A.).
Four hours after the application, the dressing was removed and the remaining test substance removed using a tissue moistened with tap-water and
subsequently a dry tissue. After removal of the dressing it was noted that the test substance had spread outside the skin-area that had been covered by the patch (approximate size of area; 4 x 4 cm) and that the area was sticky. In order to facilitate the scoring, the skin areas concerned of all animals were re-shaved before the observation on days 3 and 22. The skin areas of animal 3908 were also re-shaved before the observation on days 4 and 8.

OBSERVATIONS
Viability/Mortality/Toxicity: Daily
Body Weight: Day 1 of test ( prior to application)
Irritation: The skin reactions were assessed at approximately 50 minutes, 24, 48 and 72 hours and 7, 14 and 21 days after the removal of the
dressings and test substance.

Skin sites were scored as described below.

INTERPRETATION OF RESULTS
The irritation scores and all other observations were recorded on data sheets and transcribed for compilation and analysis.
The individual scores for erythema and oedema are summarised in tabular form.

The test results were evaluated according to the EEC criteria for general classification and labelling requirements for dangerous substances and
preparations (EEC Directive 91/325/EEC, Amendment to Annex V I of the Directive 67/548/EEC).

A primary irritation index was calculated by combining the average skin irritation scores for erythema and oedema after 24 and 72 hours. -Using the following table of primary irritation index, the degree of irritation can be obtained (Draize, J.H., Woodard, G. and Calvery, H.O., 1944).

Primary irritation index Degree of irritation
0 non - irritating
0 . 1 - 2.0 mildly irritating
2 . 1 - 5.0 moderately irritating
5 . 1 - 8.0 severely irritating
Note: Where the scoring procedure and the clinical judgement were not in agreement, the assessment of irritancy was based on the latter.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

primary dermal irritation index (PDII)

Score:

5.2

Results 2

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 50 min

Score:

2.7

Max. score:

4

Reversibility:

fully reversible within: 21 d

Remarks on result:

other: Erythema score 3, was noted at the edges of the treated area in all 3 animals. The remaining area was showed erythema score 2. Stickiness of the treated skin was noted.

Results 3

Irritation parameter:

erythema score

Basis:

mean

Time point:

24 h

Score:

2.3

Max. score:

4

Reversibility:

fully reversible within: 21 d

Remarks on result:

other: ~50% of the treated area showed erythema score 3 and ~50% erythema score 2 in one animal. Stickiness of the edges of the treated areas was noted in all 3 animals.

Results 4

Irritation parameter:

erythema score

Basis:

mean

Time point:

48 h

Score:

3.7

Max. score:

4

Reversibility:

fully reversible within: 21 d

Remarks on result:

other: Slight eschar formation was observed at the edges of the treated area of one animal. The remaining area showed erythema score 3. Remnants of test material at the edges of the treated areas in all 3 animals.

Results 5

Irritation parameter:

erythema score

Basis:

mean

Time point:

72 h

Score:

4

Max. score:

4

Reversibility:

fully reversible within: 21 d

Remarks on result:

other: Slight eschar formation was observed at the edges of the treated areas of two animals. The remaining area showed erythema score 3. Remnants of test material was noted at the edges of the treated area in one animal

Results 6

Irritation parameter:

erythema score

Basis:

mean

Time point:

7 d

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 21 d

Remarks on result:

other: New skin formation was observed in the treated area, which was covered by a thick layer of scales in all 3 animals.

Results 7

Irritation parameter:

erythema score

Basis:

mean

Time point:

14 d

Score:

0.3

Max. score:

4

Reversibility:

fully reversible within: 21 d

Remarks on result:

other: New skin formation was observed in the treated area, which was covered by a thick layer of scales in all 3 animals.

Results 8

Irritation parameter:

erythema score

Basis:

mean

Time point:

21 d

Score:

0

Max. score:

4

Remarks on result:

other: Scaliness was observed in all 3 animals.

Results 9

Irritation parameter:

edema score

Basis:

mean

Time point:

24 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 21 d

Results 10

Irritation parameter:

edema score

Basis:

mean

Time point:

48 h

Score:

1.3

Max. score:

4

Reversibility:

fully reversible within: 21 d

Results 11

Irritation parameter:

edema score

Basis:

mean

Time point:

72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 21 d

Results 12

Irritation parameter:

edema score

Basis:

mean

Time point:

7 d

Score:

0.3

Max. score:

4

Reversibility:

fully reversible within: 21 d

Results 13

Irritation parameter:

edema score

Basis:

mean

Time point:

21 d

Score:

0

Max. score:

4

Irritant / corrosive response data:

IRRITATION
The observed skin irritation consisted of slight eschar formation at the edges of the treated skin area in animals 3906 and 3907, severe erythema in animal 3908 and slight oedema in all three animals. The skin irritation had resolved within 14 days in animals 3906 and 3907 and within 3908 within 21 days after exposure .
Scaliness was observed in all three animals on day 8, 15 and 22.

CORROSION
There was no evidence of a corrosive effect on the skin.

COLOURATION
Remaining test substance that could not be removed, caused stickiness of the treated skin-area in all animals. From day 2 onwards the remnants and/or stickiness were noted at the edges of the treated area only and had disappeared in animals 3906 and 3907 by day 4 and in animal 3908 by day 8.

TOXICITY SYMPTOMS / MORTALITY
No symptoms of systemic toxicity were observed in the animals during the test period and no mortality occurred.

Other effects:

None

Any other information on results incl. tables

CALCULATIONS FOR EEC CLASSIFICATION

Observation   Rabbit A            Rabbit B        Rabbit C
  Time    Erythema/Edema   Erythema/Edema           Erythema/Edema

24 hrs            2          2          3          2            2            2

48 hrs            3          1          4          1            4            2

72 hrs            4          2          4          2            4            2

MEAN VALUE  3.0        1.7        3.7        1.7          3.3          2.0

Applicant's summary and conclusion

Interpretation of results:

Category 2 (irritant)

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Dowtherm J resulted in a primary irritation index of 5.2 (severely irritating) when applied to the intact rabbit skin.

Executive summary:

The purpose of this study was to assess the possible irritation or corrosion potential of DOWTHERM J (> 95% dialkylbenzene) when a single dose was placed on the skin of rabbits.

This study was carried out in accordance with OECD Guideline No. 404, "Acute Dermal Irritation/Corrosion" and EEC Directive 84/449/EEC, Part B.4, "Acute Toxicity - Skin Irritation". DOWTHERM J was applied onto shaved skin of three female albino rabbits using semi-occlusive dressings for 4 hours, followed by seven observations at approximately 1, 24, 48 and 72 hours and 7, 14 and 21 days after removal of the dressings and remaining test substance.

Under the conditions of this study, DOWTHERM J resulted in slight eschar formation in two animals and severe erythema in the other and slight oedema in all animals. The skin irritation had resolved within 14-21 days. No corrosive effect occurred on the skin in any of the three rabbits. In (parts of) the area of application, stickiness and/or remnants of DOWTHERM J were noted at the first three to four observations during the study.

No signs of systemic intoxication were observed during the study period.

DOWTHERM J resulted in a primary irritation index of 5.2 (severely irritating) when applied to the intact rabbit skin.

According to the EEC criteria for general classification and labelling requirements for dangerous substances and preparations (EEC Directive 91/325/EEC, Amendment to Annex VI of the EEC Directive 67/548/EEC), DOWTHERM J should be labelled as a skin irritant.