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Toxicological information

Skin sensitisation

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Administrative data

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16.09.1991 to 16.06.1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 406 (Skin Sensitisation)
Deviations:
yes
Remarks:
; no info on when sensitivity test was done - OECD 406 states that should be done every 6 months.
GLP compliance:
yes
Type of study:
guinea pig maximisation test
Justification for non-LLNA method:
The current accepted and preferred method for skin sensitisation testing according to the REACH legislation (EC no 1907/2006) and CLP Regulation (EC No 1272/2008) is the murine local lymph node assay (LLNA). A validated test method, OECD TG 429 (OECD 2002) is available for the LLNA. The guideline acknowledges the limits of the LLNA, and states that there are instances where test substance classes or substances containing functional groups shown to act as potential confounders make the use of guinea pig tests more appropriate. It is concluded that the LLNA is not applicable where the properties of the test material cause interference in the accuracy of the LLNA (OECD 2002). The statement in the OECD TG 429 is given with reference to the findings of Basketter et al. (2009a), who demonstrated false positives in silicone based substances which had previously been demonstrated to be non-sensitisers in the guinea pig maximisation test (GPMT). The importance of available evidence from guinea pig results, consideration of chemical reactivity, epidermal bioavailability and clinical and experimental human data are emphasised as central to reaching appropriate regulatory decisions for substances which have been shown to fall outside the specificity of the LLNA (Basketter et al., 2009b). The non-applicability of the LLNA for silicone based substances has also been demonstrated by Petry et al. (2012). The sensitisation potential of polyfunctional silicone materials was tested in a comparative study investigating the GPMT and the LLNA assays, which found the five tested substances to be negative in the GPMT whereas they were concluded to be weak to moderate skin sensitisers in the LLNA (Petry et al., 2012).

Test material

Reference
Name:
Unnamed
Type:
Constituent

In vivo test system

Test animals

Species:
guinea pig
Strain:
Hartley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Iffa- Credo (69592 L'Arbresle Cedex - France), Elevage Lebeau (78950 Gambais - France), Interfauna (37600 Loches - France), Charles River France.
- Age at study initiation: 'young' adult
- Weight at study initiation: 300 - 500 g
- Housing: by sex and in groups of five or six (2 for preliminary studies), in polystyrene cages with perforated flooring.
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum
- Acclimation period: At least one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20±3
- Humidity (%): 30-70
- Air changes (per hr): No data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 16.09.1991 to 16.06.1992

Study design: in vivo (non-LLNA)

Induction
Route:
intradermal and epicutaneous
Vehicle:
other: Sterile Codex liquid paraffin
Concentration / amount:
25%
Challenge
Route:
epicutaneous, occlusive
Vehicle:
other: Sterile Codex liquid paraffin
Concentration / amount:
10%
No. of animals per dose:
Preliminary studies (minimum of 3): 2 males, 2 non-pregnant females, per study.
Main study: Control group: 10 males, 10 non-pregnant females.
Treated group: 10 males, 10 non-pregnant females. Two extra guinea pigs (1/sex) treated to allow for any possible non-treatment-related deaths.
Details on study design:
RANGE FINDING TESTS: 0.1 mL intradermal injection of 50, 25 and 10% was administered to the dorsal region in order to determine the concentration that will provoke a weak to moderate irritation and which is not toxic. The skin was evaluated at each concentration at 24 and 48 hours after the injections, according to the scale of Magnusson and Kligman. For the topical application a 48 hour occlusive patch test was performed with 50 and 25%. The aim of the topical applications is to determine the concentration that will provoke a weak to moderate irritation and which is non-toxic. The skin was evaluated at each concentration at 24 and 48 hours after the injections, according to the scale of Magnusson and Kligman.

To determine the challenge concentration a 0.5 mL topical application of the test substance was applied using a 24 hour occlusive patch test in order to determine the maximum non-irritating concentration. The treated skin was evaluated at 24 and 48 hours after removal of the patches according to the above mentioned scale.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: Two (one intradermal on Day 1 and one topical on Day 9)
- Exposure period: Topical application was for 48 hours
- Test groups: Intradermal: 3 series of 2 x 0.1 mL injections: 1) Freund's complete adjuvant at 50% (v/v) in an isotonic injectable solution; 2) test substance in a 25% (v/v) solution in Sterile Codex liquid paraffin; 3) mixture 50/50 (v/v): test substance in a 50% (v/v) solution in Sterile Codex liquid paraffin + Freund's complete adjuvant at 50% (v/v) in an isotonic injectable solution, i.e. a final 25% concentration of the test substance.
Topical occlusive: 0.5 mL of the test substance in a 50% (v/v) solution in Sterile Codex liquid paraffin.
- Control group: The intradermal injections and the topical oclusive application for 48 hours were conducted under the same conditions as in the treated group, Sterile Codex liquid paraffin replacing the test substance.
- Site: clipped dorsal shoulder region
- Concentrations: 25% solution (weak to moderate irritation in preliminary study)

B. CHALLENGE EXPOSURE
- No. of exposures: One
- Day(s) of challenge: Following 11 days 'rest period' the challenge phase was initiated on Day 22.
- Exposure period: 24 hours
- Test and control groups: Topical occlusive application for 24 hours was performed in the treated and control group with the test substance in a 10% (v/v) solution in Sterile Codex liquid paraffin and at a rate of 0.5 mL.
- Site: Clipped and shaved flank
- Concentrations: 10% (maximum non-irritating concentration)
- Evaluation (hr after challenge): 24 and 48

OTHER: Histopathological examinations of the skin were performed for three animals of the treated group which showed doubtful macrscopic reactions at 48 hours.
Challenge controls:
Vehicle challenge
Positive control substance(s):
no
Remarks:
Sensitivity test conducted (no date)

Results and discussion

Positive control results:
No positive controls. However, it appears that the laboratory had conducted the same protocol with reference substances to show the sensitivity of their methodology.

In vivo (non-LLNA)

Resultsopen allclose all
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
10% TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema or edema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females).
Reading:
2nd reading
Hours after challenge:
48
Group:
negative control
Dose level:
10 % TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema or edema in any animal. Mild desquamation at test substance site at 24 and 48 hour readings (observed in more males than females).
Reading:
1st reading
Hours after challenge:
24
Group:
test group
Dose level:
10% TS
No. with + reactions:
0
Total no. in group:
20
Clinical observations:
No erythema and edema in any animal. Desquamation in one animal.
Remarks on result:
no indication of skin sensitisation
Reading:
2nd reading
Hours after challenge:
48
Group:
test group
Dose level:
10% TS
No. with + reactions:
3
Total no. in group:
20
Clinical observations:
No erythema/edema in males, Grade 1 erythema/edema in three females, where subsequent histopathology revealed no signs of cell mediated delayed hypersensitivity. 7/10 males and 4/10 females showed desquamation (including the three with erythema/edema).
Remarks on result:
no indication of skin sensitisation
Group:
positive control
Remarks on result:
not measured/tested

Any other information on results incl. tables

Signs of irritation were noted during the induction. Although macroscopic examination showed grade 1 erythema/edema in 3 females 48 h after challenge subsequent histopathological examinations did not reveal any lesion of delayed hypersensitivity in the those animals. No noticeable cutaneous abnormality was noted in the 20 guinea pigs examined in the control group.

Applicant's summary and conclusion

Interpretation of results:
other: CLP/EU GHS criteria are not met, no classification required according to Regulations (EC) No 1272/2008
Conclusions:
In a Guinea pig Maximisation Test conducted to GLP and OECD 406 (reliability score 1) triethoxy(methyl)silane was not sensitising to the skin.