Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1989-08-21 to 1989-09-21
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions: No positive control (not required by 1981 version of Test Guideline)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1989

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Version / remarks:
(1981)
GLP compliance:
no
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
A skin sensitization test according to OECD 406 has already excisted since 1989 and is sufficient for evaluation of the skin sensitisation potential of the test substance.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
2,2,4(or 2,4,4)-Trimethylhexanedioic acid of Hüls AG, produced 12 May 1989.
Purity 88 %; impurities mainly dicarboxylic acids with < 9 carbon atoms, in particular
- 5 % methylpentanedioic acid
- 2 % methylbutanedioic acid, CAS RN 498-21-5

In vivo test system

Test animals

Species:
guinea pig
Strain:
Dunkin-Hartley
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS: 
- Strain: Dunkin-Hartley (Bor: DHPW)
- Sex: female
- Source: F. Winkelmann, Borchen (Germany)
- Weight at study initiation: 449 g (mean test); 468 g (mean control)
- Controls: 10 animals; treatment: vehicle
- Diet: ad libitum, special diet for guinea pigs, SSniff G
- Water: ad libitum, tab water
- Acclimation period: 5-8 days
ENVIRONMENTAL CONDITIONS
- Temperature: 20 +/- 1 °C
- Humidity: 60 +/- 5 %
- Photoperiod: 12 hours artificial light, 12 hours dark

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
intradermal and epicutaneous
Vehicle:
corn oil
Concentration / amount:
1st application: Induction 0.1 % intracutaneous
2nd application: Induction 30 % occlusive epicutaneous
3rd application: Challenge 10 % occlusive epicutaneous
Challengeopen allclose all
Route:
epicutaneous, occlusive
Vehicle:
corn oil
Concentration / amount:
1st application: Induction 0.1 % intracutaneous
2nd application: Induction 30 % occlusive epicutaneous
3rd application: Challenge 10 % occlusive epicutaneous
No. of animals per dose:
20 test
10 control
Details on study design:
ADMINISTRATION/EXPOSURE
- Induction schedule: injection followed 1 week later by patch treatment  for 48 hours
- Injection details: 0.1 ml each at 6 positions on shoulders:
2 x Freund's Complete Adjuvant / deionized water (50:50)
2 x test substance 10 % in corn oil
2 x test substance 10 % in Freund's Complete Adjuvant / corn oil (50:50)
simultaneous and symmetrical application of each solution
controls: corn oil instead of test substance
- Challenge schedule: 2 weeks after end of induction, patch treatment for 24 hours
- Concentrations used for challenge:
10 % in corn oil with filter paper on left side; corn oil on opposite side
 readings 24 and 48 hours after removal of patch
- Rechallenge: 1 week after first challenge
3 % in corn oil with filter paper on right (!) side; corn oil on  opposite side
  readings 24 and 48 hours after removal of patch
- Positive control: no
EXAMINATIONS
- Grading system: possible scores 0 / 1 / 2 / 3
 0 % of animals scored > 0: no sensitization
 1 -  8 % of animals scored > 0: very slight sensitization
 9 - 28 % of animals scored > 0: slight sensitization
29 - 64 % of animals scored > 0: distinct sensitization
65 - 80 % of animals scored > 0: severe sensitization
81 -100 % of animals scored > 0: extreme sensitization
Challenge controls:
treated with vehicle (corn oil)
Positive control substance(s):
no

Results and discussion

Positive control results:
no positive control

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
10 % in corn oil
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
no reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 10 % in corn oil. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: no reactions.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
10 % in corn oil
No. with + reactions:
7
Total no. in group:
20
Clinical observations:
no reactions
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 10 % in corn oil. No with. + reactions: 7.0. Total no. in groups: 20.0. Clinical observations: no reactions.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10 % in corn oil
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no reactions
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 10 % in corn oil. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no reactions.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10 % in corn oil
No. with + reactions:
5
Total no. in group:
10
Clinical observations:
no reactions
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 10 % in corn oil. No with. + reactions: 5.0. Total no. in groups: 10.0. Clinical observations: no reactions.
Reading:
rechallenge
Hours after challenge:
24
Group:
test group
Dose level:
3 % in corn oil
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
no reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 24.0. Group: test group. Dose level: 3 % in corn oil. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: no reactions.
Reading:
rechallenge
Hours after challenge:
48
Group:
test group
Dose level:
3 % in corn oil
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
no reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 48.0. Group: test group. Dose level: 3 % in corn oil. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: no reactions.
Reading:
rechallenge
Hours after challenge:
48
Group:
negative control
Dose level:
3 % in corn oil
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
no reactions
Remarks on result:
other: Reading: rechallenge. . Hours after challenge: 48.0. Group: negative control. Dose level: 3 % in corn oil. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: no reactions.

Any other information on results incl. tables

- Sensitization reaction (1st challenge):
  0/20 animals positive at 24 hours, 7/20 positive at 48 hours
  0/10 control animals positive at 24 hours, 5/10 positive at 48 hours
  test group: 1/20 animals showed slight skin irritation upon corn oil treatment on opposite side only at 48 hours
  control: no skin reaction upon corn oil treatment on opposite side
- Sensitization reaction (rechallenge):
  0/20 animals positive at 24 hours and at 48 hours = no sensitization
  no animals positive in control group
  no skin reaction upon corn oil treatment on opposite side (both groups)
- Clinical signs:
  1st induction, FCA application sites: severe erythema and edema, necroses
  1st induction, FCA + test substance + vehicle application sites: severe erythema and edema, slight necroses
  1st induction, FCA + vehicle application sites: severe erythema and  edema, slight necroses
  1st induction, vehicle application sites: slight erythema
  1st induction, test substance application sites: slight erythema
  2nd induction, test and control groups: inflammation of all FCA injection sites with bleeding in some animals; slight inflammation in 

vehicle and test substance injection sites; restlessness of all animals with 

scratching in the application area; significant crust formation within 

24 hours after patch removal.
- Other: Mean body weight gain 122 g in test group, 124 g in control group = no effect of treatment.

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
Classification: not sensitizing
Executive summary:

The skin sensitizing properties of 2,2,4(or 2,4,4)-trimethylhexanedioic acid were determined in a guinea pig maximation test according to OECD TG 406 (positive controls not required by 1981 guideline version). Twenty female guinea pigs were intradermally injected 2,2,4(or 2,4,4)-trimethylhexanedioic acid at 0.1 % in corn oil and one week later epidermally exposed to a 30 % concentration of test substance for 48 hours (occlusive). Ten control animals were similary treated, but with vehicle alone. Two weeks after the epidermal application all animals were challegend with 10 % test substance and with vehicle (24 hours occlusive). For the rechallenge application one week later 3 % test substance were used . Under the conditions of the test no sensitizing effects were observed in any of the 20 animals at all. Based on these results, 2,2,4(or 2,4,4)-trimethylhexanedioic acid should not be classified as a contact sensitizer.