Diethylbenzene

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study.

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Remarks:

Not specified in report.

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

The study was conducted prior to the LLNA guidelines

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

Details on test material:

Polyethylbenzene coded MF335
Ethanol (100%) Lot D2-72331 was received from Gold Shield Company, Hayward, CA.
Nanograde acetone, Lot 10212 was received from VWR Scientific, Inc., San Francisco, CA

In vivo test system

Test animals

Species:

guinea pig

Strain:

Hartley

Sex:

female

Details on test animals and environmental conditions:

Female Hartley albino guinea pig, CEHC Lot# 63, were obtained from Charles River Breeding Laboratory , Portage, Michigan. The guinea pigs were allowed a one week quarantine followed by a 22 day acclimation period. The animals weighed 395-498 grams and were nine weeks old on the first day of dosing. All animals were weighed on Day 0 and on the last day of scoring for challenge. Animals were housed individually in stainless steel wire-bottom cages in a temperature-regulated room. In the study room, the temperature ranged from 20-22C and the relative humidity from 40-59%. The photoperiod was a 12-hour light/dark cycle. The animals had unlimited access to Purina Certified Guinea Pig Chow #5026 and water except during the test material exposure period.

Selection and Identification of Animals
Animals were randomly assigned to treatment groups using the WTALOC program of the DATATOX System (INSTEM Computer Systems Plc., Stone, Staffordshire, England). There were no signifcant differences in mean body weights between groups of animals at the beginning of the study. All animals were identified by a numerically coded ear punch and by a color-coded cage card that stated the animal number, sex, study number, test material name and code number, dosage and date of treatment.

Study design: in vivo (non-LLNA)

Induction

Induction 1

Route:

epicutaneous, occlusive

Vehicle:

other: ethanol or acetone

Induction 2

Concentration / amount:

Induction:  10% PEB (w/w in ethanol);  Challenge: 5% PEB  (w/w in acetone)

Challenge

Challenge 1

Route:

epicutaneous, occlusive

Vehicle:

other: ethanol or acetone

Challenge 2

Concentration / amount:

Induction:  10% PEB (w/w in ethanol);  Challenge: 5% PEB  (w/w in acetone)

No. of animals per dose:

PEB (20)    Induction:  10% PEB (w/w in ethanol);  Challenge: 5% PEB  (w/w in acetone)         
Irritation Control (10)  Induction: 100% ethanol; Challenge:5% PEB (w/w in acetone)         
Vehicle Irritation Control (5)         Induction: 100% ethanol; Challenge:100% acetone

Details on study design:

Induction

Over a 15-day period, three occluded epicutaneous applications were  administered on Wednesdays.  The left flank of each animal was clipped  the day before each induction application.  All dosing solutions were  administered with a manual pipettor.  A Hill Top Chamber containing 0.3  ml of the dosing mixture was applied to the left flank of each animal.   The chambers were occluded by a rubber dental dam pulled taut and  fastened to the bottom of the restrainer with clips.  After approximately  six hours the dental dam and chamber were removed, the animals was taken  from the restrainer and returned to its cage.         

Challenge Treatment

The animals were challenged 14 days after the third induction  application.  The right flank of each animal was clipped free from fur on  the day before dosing. A Hill Top Chamber containing 0.3 ml of the dosing  mixture was applied to the right flank of each animal and wrapped as  described above.  After approximately six hours the dental dam and  chamber were removed, the animals was taken from the restrainer and  returned to its cage.   Approximately 24 hours after the beginning of the  challenge exposure, the test sites and surrounding areas were depilated  with a lotion hair remover.  The depilatory was washed off thoroughly  with warm tap water, and the animals were dried and returned to their  cages.  Skin scorings were conducted at 24 and 48 hours after unwrapping,  and at least 2 hours after depilation, using the system described by  Buehler. Edema was noted but not scored.

Assessment of Skin Irritation and Sensitization Potential
In order to assess the skin sensitization potential of Polyethylbenzene, the skin irritation scores of test animals and their corresponding irritation controls were compared. An animal induced with the test material was considered to be sensitized of its challenge irritation scores were greater and/or more persistent than scores for animals in the corresponding irritation control group following a first exposure to the test material.


Experimental Design:
One group of 20 female Hartley albino guinea pigs was induced with 10% Polyethylbenzene weight/weight (w/w) in ethanol and challenged with 5%  
Polyethylbenzene (PEB)  (w/w) in acetone.  Additional groups of 10 and 5  female guinea pigs served as concurrent irritation controls for the  
Polyethylbenzene and vehicle, respectively. Dosing mixtures were sampled for homogeneity and stability after dose  preparation for the first induction application and concentration  analysis of the 5% Polyethylbenzene w/w in acetone and 100% acetone.   

No. of Animals                                   
PEB (20)    Induction:  10% PEB (w/w in ethanol);  Challenge: 5% PEB (w/w in acetone)         
Irritation Control (10)  Induction: 100% ethanol; Challenge:5% PEB (w/w in acetone)         
Vehicle Irritation Control (5)    Induction: 100% ethanol; Challenge:100% acetone        

Clinical observations:
Each animal was observed once daily for physiological or behavioral  abnormalities, overt signs of toxicity and a viability check.
Statistical Analysis:
Body weights were statistically analyzed

Challenge controls:

Irritation Control (10 animals): Induction: 100% ethanol; Challenge:5% PEB (w/w in acetone)
Vehicle Irritation Control (5)    Induction: 100% ethanol; Challenge:100% acetone   

Positive control substance(s):

no

Results and discussion

Positive control results:

No data

In vivo (non-LLNA)

Results

Results 1

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 5%. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Results 2

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

none

Remarks on result:

other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 5%. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: none.

Results 3

Reading:

other: readings after 24 and 48 hours

Hours after challenge:

48

Group:

positive control

Dose level:

100% ethanol induction and 5% w/w in acetone

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

none

Remarks on result:

other:

Remarks:

No sensitization responses were observed. Dermal responses observed within each test group were equivalent. With the exception of 3 animals, no to slight, patchy erythema was observed in all groups at 24 and 48 hours after challenge. Slight patchy erythema to slight, but confluent or moderate, patchy eythema was observed in one vehicle control and two test material-induced animals 24-48 hours after challenge

Results 4

Reading:

other: readings after 24 and 48 hours

Hours after challenge:

48

Group:

negative control

Dose level:

100% ethanol induction and 100% acetone challenge

No. with + reactions:

1

Total no. in group:

5

Clinical observations:

none

Remarks on result:

other:

Remarks:

No sensitization responses were observed. Dermal responses observed within each test group were equivalent. With the exception of 3 animals, no to slight, patchy erythema was observed in all groups at 24 and 48 hours after challenge. Slight patchy erythema to slight, but confluent or moderate, patchy eythema was observed in one vehicle control and two test material-induced animals 24-48 hours after challenge

Any other information on results incl. tables

Analytical Results
Homogeneity samples contained 87% of the target concentration with a  coefficient of variation of 0.85 for 6 

samples.  The analysis of the  stability samples showed that they contained 101% of the initial  concentration. 

Concentration check samples taken at challenge were found to contain 74%  of the target concentration. Animals were observed for mortality or compound-related signs of toxicity  during the study.

Animal observations
No mortality or compound-related signs of toxicity were observed during  the study.

Skin Sensitization
Challenge
No sensitization responses were observed.Dermal responses observed within each test group were equivalent. With the exception of three animals,no to slight, patchy erythma was observed in all groups at 24 and 48 hours after challenge. Slight patchy erythema to slight, but confluent or moderate, patchy erythema was observed in one vehicle control and two test material-induced animals 24-48 hours after challenge.

Body Weights
Statistical analysis showed no significant differences for mean body weights or mean body weight gain between 

control and treated animals.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Remarks:

Migrated information

Conclusions:

No sensitization responses were observed in animals induced with 10% Polyethylbenzene and challenged with 5% Polyethylbenzene. Therefore, Polyethylbenzene is not considered to be a sensitizer.

Executive summary:

The skin sensitization potential of Polyethylbenzene was evaluated using the procedure described by Buehler. One group of 20 female guinea pigs was induced with 10% Polyethylbenzene weight/weight (w/w) in ethanol and challenged with 5% Polyethylbenzene weight/weight (w/w) in acetone. Additional groups of 10 and 5 female guinea pigs served as concurrent irritation controls for the Polyethylbenzene and vehicle, respectively.

No sensitization responses were observed in animals induced with 10% Polyethylbenzene and challenged with 5% Polyethylbenzene.

Therefore, Polyethylbenzene is not considered to be a sensitizer under the conditions tested.