Registration Dossier

Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
November 14 - December 4, 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to the OECD 429 guideline and in compliance with GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
Deviations:
no
GLP compliance:
yes
Type of study:
mouse local lymphnode assay (LLNA)

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid: pellets
Details on test material:

- Physical state: solid
- Analytical purity: 90.2 %
- Lot/batch No.: 2012-06
- Expiration date of the lot/batch: 1.1.2013
- Storage condition of test material: at ambient temperature

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan laboratories srl, Italy
- Age at study initiation: 8-12 weeks old
- Diet (e.g. ad libitum): Certified laboratory food (MP-OS-06)


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24 °C
- Humidity (%): 55 +/- 10 %
- Air changes (per hr): 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12

Study design: in vivo (non-LLNA)

Induction
Route:
epicutaneous, open

Study design: in vivo (LLNA)

Vehicle:
dimethyl sulphoxide
Concentration:
Potassium isoamyl xanthate was tested at five concentrations (2.5 %, 5 %, 10 %, 25 % and 50 %)
No. of animals per dose:
5 animals / dose
Details on study design:
RANGE FINDING TESTS:
- Compound solubility:
- Irritation: no observed irritation
- Lymph node proliferation response:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- The animals were weighed and allocated to the test group based on their actual body weight. Each group was approximately equal initial body weight.
- The test item in the appropriate dilution (25ul) was applied to the dorsum of each ear on day 1, 2 and 3.
- On day 6 a volume of 250 ul of phophate-buffered saline (PBS) containing 20uCi of 3H-methyl thymidine was injected into all test and control mice via the tail vein.
- Five hours later, the animals were sacrificed. The draining auricular lymph nodes from each ear were excised and pooled in PBS for each experimental group.
- Cell suspenson of lymph node cells were prepared and counted for 3H-methyl thymidine radioactivity.
- Criteria used to consider a positive response: Results are expressed as the Stimulation Index (SI). The SI is obtained by dividing the pooled radioactive incorporation for each treatment group by the incorporation of the pooled vehicle control group; this yield a mean SI. The concentration eliciting a SI of 3 is edientified as the EC3 value and was calculated by linar interpolation of points on the dose-response curve, immediately above and below the threefold threshold with the co-ordinates (a,b) and (c,d), respectively according to the equation: EC3=c+[(3-d)/(b-d)] * (a-c).

TREATMENT PREPARATION AND ADMINISTRATION:
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)

Results and discussion

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: 2.5 % 1.57 5 % 2.21 10% 2.94 25% 4.12 50% 4.59
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: 2.5 % 749.33 5 % 1053.69 10% 1402.08 25% 1966.09 50% 2189.85

Applicant's summary and conclusion

Interpretation of results:
sensitising
Remarks:
Migrated information Criteria used for interpretation of results: expert judgment
Conclusions:
The skin sensitising potential of potassium isoamyl xanthate was assessed using murine local lymph node assay. Based on the results and SI values the substance in LLNA was evaluated as a sensitiser.
Executive summary:

This study was regarded reliable without restrictions since the the study was conducted according to the OECD 429 guideline and in compliance with GLP.

Potassium isoamyl xanthate was applied over three consecutive days at five concentrations. Lymph node weights were measured and DPM values were calculated in all treated groups. The changes were dose dependent. The SI values over 3 were determined at concentrations 25 and 50 %. In general, when the SI for any single treatment dose group is ≥ 3, the test item is regarded as a potential skin sensitiser. According to the EC3 value (10.77 %) calculated for potassium isoamyl xanthate, the substance should be classified as skin sensitiser according to CLP Regulation 1272/2008.