Sodium cyanate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 2009-02-17 to 2009-04-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

440/2008/EC

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Sodium cyanate

EC Number:

213-030-6

EC Name:

Sodium cyanate

Cas Number:

917-61-3

Molecular formula:

CNO.Na

IUPAC Name:

sodium cyanate

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

In vivo test system

Test animals

Species:

mouse

Strain:

CBA

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Hungarian Supplier, WOBE Kereskedelmi Kft., H-1164, Budapest, Garmada u. 10.
- Age at study initiation: Young adult, 11-12 weeks old, age-matched within one week
- Weight at study initiation: 20.3 – 21.5 grams (the weight variation in animals involved in the study did not exceed +/- 20 % of the mean weight)
- Housing: Individual caging / mice were provided with glass tunnel-tubes
- Diet (e.g. ad libitum): Animals received ssniff® SM R/M-Z+H "Autoclavable complete diet for rats and mice – breeding and maintenance" (Batch Number: 266 0944, Expiry Date: January 2009 and Batch Number: 376 1603, Expiry Date: May 2009) produced by ssniff Spezialdiäten GmbH, D-59494 Soest Germany ad libitum, and tap water from municipal supply, as for human consumption from 500 ml bottle ad libitum. The contents of the diet provided by the Supplier are listed in Appendix 6. The diet and drinking water are routinely analysed and are considered to not contain any contaminants that could reasonably be expected to affect the purpose or integrity of the study. Copies of the relevant Certificates of Analysis are retained in the Archive at LAB Research Ltd.
- Acclimation period: 36 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3 °C
- Humidity (%): 24 - 70 %
- Air changes (per hr): 15-20 air exchange/hour by central air-condition system.
- Photoperiod (hrs dark / hrs light): 12 light hours daily, from 6.00 a.m. to 6.00 p.m.


IN-LIFE DATES: From: 2009-02-26 To: 2009-03-04

Study design: in vivo (LLNA)

Vehicle:

other: 1 (w/v) % Pluronic PE9200 in water

Concentration:

2.5 %, 5 % and 10 %

No. of animals per dose:

4

Details on study design:

RANGE FINDING TESTS:
- Compound solubility:
The test item vehicle compatibility was verified in a Preliminary Compatibility Test with
1. Acetone: Olive oil 4:1 mixture (AOO),
2. N,N-dimethylformamide,
3. Propylene glycol,
4. Dimethyl sulphoxide and
5. 1 (w/v) % Pluronic.
The test item was insoluble in solvents 1-4. The suitable vehicle was 1 % Pluronic. The maximum soluble concentration was 10% in this vehicle. Pluronic PE9200 is a surfactant, which ensured the formulation remained on the ears of the animals when applied topically. Although this vehicle is not specifically listed in the OECD guideline, it has been validated with positive control materials in international laboratories and LAB Research Ltd and represents a worst case vehicle.

- Irritation:
No cutaneous reaction was observed in any of the treated groups.
- Lymph node proliferation response:
The observations recorded in this preliminary test suggest that the formulations, the application of the material and the local effects on the animal are acceptable for a valid LLNA.


MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: LLNA
- Criteria used to consider a positive response:
The test item is regarded as a sensitizer if both of the following criteria are fulfilled:
- That exposure to at least one concentration of the test item resulted in an incorporation of 3HTdR at least 3-fold or greater than recorded in control mice, as indicated by the stimulation index.
- The data are compatible with a conventional dose response, although allowance must be made (especially at high topical concentrations) for either local toxicity or immunological suppression.



TREATMENT PREPARATION AND ADMINISTRATION:
During the assay each mouse was topically dosed on the dorsal surface of each ear with 25 ml of the appropriate formulation applied using a pipette. Each animal was dosed once a day for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

mean

Results and discussion

Positive control results:

The positive control group animals were treated with 25 (w/v) % HCA solution in a relevant vehicle (1% Pluronic) concurrent to the test item groups. The positive control substance was chosen according to the OECD guideline.

In vivo (LLNA)

Results

Results 1

Key result

Parameter:

SI

Value:

>= 3

Test group / Remarks:

No significant lymphoproliferative response (SI >= 3) of sodium cyanate was observed at the concentrations applied compared to the negative control.

Results 2

Key result

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: See Table below.

Results 3

Parameter:

SI

Value:

1.4

Test group / Remarks:

at treatment concentrations of 10 %

Results 4

Parameter:

SI

Value:

2.4

Test group / Remarks:

at treatment concentrations of 5 %

Results 5

Parameter:

SI

Value:

0.8

Test group / Remarks:

at treatment concentrations of 2.5 %

Any other information on results incl. tables

DPM, DPN and Stimulation Index Values for all Groups

Test Group	Measured	Group	No. of	DPN	Stimulation
Name	DPM/group	DPM	Nodes		Index Values
Background	36,5	-	-	-	-
(5 (w/v) % TCA )
Negative control (vehicle)	728,0	691,5	8	86,4	1,0
1 % Pluronic
SONATE NC 95	988,0	951,5	8	118,9	1,4
10 % in 1 % Pluronic
SONATE NC 95	1672,0	1635,5	8	204,4	2,4
5 % in Pluronic
SONATE NC 95	585,0	548,5	8	68,6	0,8
2.5% in 1 % Pluronic
Positive control	6206,0	6169,5	8	771,2	8,9
25 % HCA
Mean background	21,1
No of nodes	8

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

In conclusion, sodium cyanate was shown to have no sensitisation potential (non-sensitizer) in the Local Lymph Node Assay under the test conditions used in this study.

Executive summary:

In this dermal sensitization study (LLNA) with sodium cyanate (95 %) in 1 (w/v) % Pluronic PE9200 in water, young adult CBA mice (4 females per group) were exposed.

Clinical Signs and Mortality

No mortality or signs of systemic toxicity were observed during the study. No significant effects were observed on animal body weights. No irritation or other cutaneous effect was observed in any group. Test item precipitate was observed on the ears of the animals in the 10 % treated group (Days 2 and 3).

Proliferation Assay

No significant lymphoproliferative response (SI >= 3) of sodium cyanate was observed at the concentrations applied compared to the negative control. Stimulation index values of the test item were 1.4, 2.4 and 0.8 at treatment concentrations of 10 %, 5 % and 2.5 %, respectively.

Interpretation of Observations

The maximum available concentration was 10 % in 1% Pluronic due to solubility. A Preliminary Irritation/Toxicity Test was performed showing that the maximum concentration of test item of 10 % was acceptable. Since there were no confounding effects of irritation or toxicity at the applied concentrations, the proliferation values obtained are considered to reflect the real potential of the test item to cause lymphoproliferation in the Local Lymph Node Assay. No significant lymphoproliferative response (SI >= 3) of sodium cyanate was observed at the applied concentrations. No dose-response to treatment was observed.

In this study, sodium cyanate is not a dermal sensitizer according to 67/548/EEC and CLP (GHS).

Reliability of the Assay

The positive control group animals were treated with 25 (w/v) % HCA solution in a relevant vehicle (1% Pluronic) concurrent to the test item groups. The results of the positive control group demonstrated the appropriate performance of the assay