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Skin sensitisation

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Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
19 Oct 2004 - 16 Dec 2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Meets national standard methods; GLP
Qualifier:
according to
Guideline:
EPA OPPTS 870.2600 (Skin Sensitisation)
Deviations:
yes
Remarks:
only historical positive control, one dose tested
GLP compliance:
yes
Remarks:
Product Safety Laboratories
Type of study:
Buehler test
Justification for non-LLNA method:
A non-LLNA test is available that was performed prior to the current data requirements, stipulated in Regulation (EC) No 1907/2006. In accordance with the same Regulation, the data were included to avoid unnecessary testing.
Species:
guinea pig
Strain:
Hartley
Sex:
male
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Elm Hill Breeding Labs
- Age at study initiation: young adult
- Weight at study initiation: 310 - 418 g
- Housing: group housing in stainless steeel cages
- Diet (e.g. ad libitum): pelleted Purina guinea pig chow #5025
- Water (e.g. ad libitum): filtered tap water
- Acclimation period: 3, 6 or 40 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 - 22
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: 20 Oct To: 19 Nov 2004
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
100% (undiluted, induction exposure), 75% (challenge exposure)
Route:
epicutaneous, occlusive
Vehicle:
water
Concentration / amount:
100% (undiluted, induction exposure), 75% (challenge exposure)
No. of animals per dose:
20 in test group and 10 in naive control group
Details on study design:
RANGE FINDING TESTS:
Test to determine the highest non-irrritating concentration of the test substance to be used as challenge dose. The test substance was applied in concentrations of 100, 75, 50 and 25% to the shaved test side using an occlusive Hill Top Chamber and gently removed after 6h exposure (identical to main study). Approximately 24 h after application, each site was evaluated for local irritation reactions.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 3 weeks
- Site: left side of each animal
- Frequency of applications: once a week
- Duration: 6 h
- Concentrations: 100%


B. CHALLENGE EXPOSURE
27 days after the first induction dose
- No. of exposures: 1
- Day(s) of challenge: 1
- Exposure period: 6 h
- Site: right side of each animal
- Concentrations: 75%
- Evaluation (hr after challenge): 24 and 48 h after the challenge application
Positive control substance(s):
yes
Remarks:
technical alpha-hexylcinnamaldehyde (historical control)
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
100%/75%
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
very faint erythema in 8/20 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: test group. Dose level: 100%/75%. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: very faint erythema in 8/20 animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
100%/75%
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
one animal with very faint erythema
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: test group. Dose level: 100%/75%. No with. + reactions: 0.0. Total no. in groups: 20.0. Clinical observations: one animal with very faint erythema.
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
0%/75%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
very faint erythema in 4/10 animals
Remarks on result:
other: Reading: 1st reading. . Hours after challenge: 24.0. Group: negative control. Dose level: 0%/75%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: very faint erythema in 4/10 animals.
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
0%/75%
No. with + reactions:
0
Total no. in group:
10
Clinical observations:
none
Remarks on result:
other: Reading: 2nd reading. . Hours after challenge: 48.0. Group: negative control. Dose level: 0%/75%. No with. + reactions: 0.0. Total no. in groups: 10.0. Clinical observations: none.

The first and the second reading of the historical positive control group gave 6/10 animals with positive reactions whereas the corresponding negative control group (5 animals) gave no reactions at both time points.

Interpretation of results:
not sensitising
Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
yes
Remarks:
1-fluoro-2,4-dinitrobenzene (DNFB) as positive  control
GLP compliance:
not specified
Type of study:
mouse local lymph node assay (LLNA)
Species:
mouse
Strain:
Balb/c
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS: 
- Source: National Cancer Institute, USA
- Age: 45 - 60 days
- Weight at study initiation: 17 - 20 g
Vehicle:
other: 15% ethanol
Concentration:
2, 4 and 6%
Details on study design:
RANGE FINDING TESTS:
- Irritation: A primary irritancy assay was performed to establish the  minimal irritating and the maximal non-irritating concentration.

TREATMENT PREPARATION AND ADMINISTRATION:
Test solutions were  prepared daily in amber vials using 15% ethanol.
Positive control substance(s):
other: 1-fluoro-2,4-dinitrobenzene (DNFB)
Statistics:
Bartlett's chi-square Test, one-way ANOVA and  Dunnett's Multiple Range t Test
Remarks on result:
other: please refer to 'any other information on results incl. tables'

RESULTS OF PILOT STUDY: minimal irritating concentration: 6%; maximal  non-irritating concentration: 4%

 
RESULTS OF TEST
- Sensitization reaction: sensitization with 2-6% did not significantly  alter cell proliferation in the auricular lymph nodes,

even though an  increase of 30% and 40% at the 4% and 6% treatment levels was measured,  respectively. A greater than

30-fold increase was measured in the  positive control.

Interpretation of results:
not sensitising
Endpoint conclusion
Additional information:

Potassium silicate as well as the read-across substance, sodium metasilicate, were not sensitizing in two different skin sensitisation tests (Buehler test and local lymph node assay). In a human case report, contact urticaria induced by sodium silicate was observed in one individual.


Migrated from Short description of key information:
Potassium silicate is not sensitising.

Respiratory sensitisation

Endpoint conclusion
Additional information:

Not required. No data available.

Justification for classification or non-classification

The available data is conclusive but not sufficient for classification.