Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2005
Reliability:
2 (reliable with restrictions)

Data source

Reference
Reference Type:
publication
Title:
company
Author:
company
Year:
2005
Bibliographic source:
company

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
yes
Remarks:
yes different treatment protocols applied
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
Methenamine
EC Number:
202-905-8
EC Name:
Methenamine
Cas Number:
100-97-0
Molecular formula:
C6H12N4
IUPAC Name:
1,3,5,7-tetraazatricyclo[3.3.1.1~3,7~]decane
Test material form:
not specified
Details on test material:
Source: Sigma-Aldrich

In vivo test system

Test animals

Species:
mouse
Strain:
Balb/c
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: RIVM
- Age at study initiation: Young adult (6-8 weeks of age)
- Housing: macrolon cages
- Diet: ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
standard conditions

Study design: in vivo (non-LLNA)

Inductionopen allclose all
Route:
other: not applicable
Vehicle:
other: acetone/olive oil (4:1 v/v)
Concentration / amount:
2.5, 5, 10, 20 %
Challengeopen allclose all
Route:
other: not applicable
Vehicle:
other: acetone/olive oil (4:1 v/v)
Concentration / amount:
2.5, 5, 10, 20 %
No. of animals per dose:
not specified (probably 4 per dose, as required in OECD guideline)
Details on study design:
According to de Jong et al., 2002 (Toxicology 176, 123-134).
In order to enhance possible low responses of weak sensitizers animals were pretreated with sodium dodecyl sulfate 1% (SDS) on the dorsum of the ears one hour before administration.
Test 1 (Short protocol): Animals were treated on days 0-1-2 and lymph node cell proliferation was determined on day 5.
Test 2 (Repeated protocol): Animals were treated on days 0-1-2. 7-14-28-35-42-49, and 56-57-58 and lymph node cell proliferation was determined on day 61.
Positive control substance(s):
not specified

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
2.5, 5, 10, 20 %
No. of animals per dose:
not specified (probably 4 per dose, as required in OECD guideline)
Details on study design:
According to de Jong et al., 2002 (Toxicology 176, 123-134).
In order to enhance possible low responses of weak sensitizers animals were pretreated with sodium dodecyl sulfate 1% (SDS) on the dorsum of the ears one hour before administration.
Test 1 (Short protocol): Animals were treated on days 0-1-2 and lymph node cell proliferation was determined on day 5.
Test 2 (Repeated protocol): Animals were treated on days 0-1-2. 7-14-28-35-42-49, and 56-57-58 and lymph node cell proliferation was determined on day 61.
Positive control substance(s):
not specified
Statistics:
EC3 was estimated by the benchmark approach.

Results and discussion

Positive control results:
no positive control.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: Test 1 (Short protocol): SI = 4.0; EC2 (L05-L95) = 19.3 (11.8-53.1); EC3 (L05-L95) = 30.6 (18.7-84.2) Test 2 (Repeated protocol): SI = 5.78
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: not given.

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information
Conclusions:
Results of the LLNA affirm the classification of methenamine as a skin sensitizer.
Executive summary:

In a Local Lymph Node Assay (LLNA) similar to OECD Guideline 429, an EC3 (test concentration, which causes a Stimulation Index (SI) of the auricular lymph nodes of 3.0) of 30.6% was determined for methenamine, while an EC3 as low as 0.96% was determined for formaldehyde in the same study. The test was performed treating young adult (6-8 weeks of age) female BALB/c mice with methenamine dissolved in a acetone-olive oil mixture (4:1). Test concentrations were 2.5, 5, 10 and 20%. In order to enhance possible low responses of weak sensitizers animals were pretreated with sodium dodecyl sulfate 1% (SDS) on the dorsum of the ears one hour before administration. In second test with repeated exposures the fist test was coonfirmed revealing a Stimulation Index of 5.78. Results of the LLNA affirm the classification of methenamine as a skin sensitizer.