Potassium cyanate

Endpoint summary

Description of key information

The test item analogue, sodium cyanate, was tested in an in vivo LLNA test according to OECD 429 and in an in vivo Bühler Test according to OECD 406. Based on the results, the test item analogue is considered to be a non-sensitiser. Since the applied read-across approach is considered to be reliable and suitable the endpoint skin sensitisation, the test item potassium cyanate has also no potential for skin sensitisation.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Reference 1

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

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

440/2008/EC

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

24th April 2002

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

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

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

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 stimulation index of the test item was determined to be 8.9.

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

Negative control (1% Pluronic)

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

10% sodium cyanate

Key result

Parameter:

SI

Value:

2.4

Test group / Remarks:

5% sodium cyanate

Key result

Parameter:

SI

Value:

0.8

Test group / Remarks:

2.5% sodium cyanate

Cellular proliferation data / Observations:

CELLULAR PROLIFERATION DATA
The following disintegrations per minute (DPM) were determined:
Vehicle: 691.5 dpm
10% test item: 951.5 dpm
5.0% test item: 1635.5 dpm
2.5 % test item: 548.5 dpm
Positive control: 6169.5 dpm

The following DPM per group was determined:
Vehicle: 728.0 dpm/group
10% test item: 988.0 dpm/group
5.0% test item: 1672.0 dpm/group
2.5 % test item: 585.0 dpm/group
Positive control: 6206.0 dpm/group

The following DPN was determined:
Vehicle: 86.4 dpn
10% test item: 118.9 dpn
5.0% test item: 204.4 dpn
2.5 % test item: 68.6 dpn
Positive control: 771.2 dpm

DETAILS ON STIMULATION INDEX CALCULATION
SI = DPN value of a treated group divided by the DPN value of the negative control group

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

BODY WEIGHTS: No significant effects were observed on animal body weights.

Interpretation of results:

GHS criteria not met

Conclusions:

In conclusion, the test item analogue, 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:

Local Lymph Node Assay according to OECD 429 and Commission Regulation (EC) No 440/2008 of 30 May 2008, B.42 was performed with CBA/CaOlaHsd mice. The aim of this study was to determine the skin sensitisation potential of the test item analogue following dermal exposure in the Local Lymph Node Assay. The test item was a white solid; vehicle compatibility was verified in a Preliminary Compatibility Test with Acetone: Olive oil 4:1 mixture (AOO), N,N-dimethylformamide, Propylene glycol, Dimethyl sulphoxide and 1 (w/v) % Pluronic. The test item was insoluble in first – fourth solvents. The suitable vehicle was 1 (w/v) % Pluronic. The maximum available concentration was 10% in this vehicle. Pluronic PE9200 is a surfactant, which ensures that 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. A Preliminary Irritation/Toxicity test was performed with the test item at concentrations of 10 % and 5 % in the selected vehicle. The 10 % concentration was considered acceptable as the maximum concentration in the main assay. In the main assay twenty female CBA/CaOlaHsd mice were allocated to five groups of four animals each:

- three groups received the appropriate formulation of test item analogue at concentrations of 10 %, 5 % and 2.5 %,

- the negative control group received the vehicle (1 % Pluronic),

- the positive control group received 25 (w/v) % HCA in relevant vehicle. The test item solutions were applied on the dorsal surface of ears of experimental animals (25 l/ear) for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in the local lymph nodes was measured by incorporation of tritiated methyl thymidine (3HTdR) and the values obtained were used to calculate stimulation indices (SI). No mortality or systemic clinical signs were observed during the study. No treatment related effect on the body weights was observed. No signs of irritation or other cutaneous effect were observed in any of the treated groups. No significant lymphoproliferative response (SI 3) of test item analogue 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. No dose-response to treatment was observed. α-Hexylcinnamaldehyde (25 (w/v) % dissolved in 1% Pluronic) was used as the positive control to demonstrate the appropriate performance of the assay. A significant lymphoproliferative response (stimulation index value of 8.9) was noted for the positive control chemical, this result confirmed the validity of the assay.

The test item analogue, sodium cyanate, is not considered to be a skin sensitizer under the test conditions chosen.

Reference 2

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

ANALOGUE APPROACH JUSTIFICATION
Both the target and the source substance show similar behaviour in aqueous medium (dissociate quickly to cyante and K+ or Na+, respectivley) and their behaviour on skin is assumed to be similar as well. Both potassium and sodium are present in cells and body fluids (e.g. essential electrolytres), therefore the potential for skin sensitisation is due the cyanate ion.

Reason / purpose for cross-reference:

read-across source

Type of study:

mouse local lymph node assay (LLNA)

Key result

Parameter:

SI

Value:

1

Test group / Remarks:

Negative control (1% Pluronic)

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

10% sodium cyanate

Key result

Parameter:

SI

Value:

2.4

Test group / Remarks:

5% sodium cyanate

Key result

Parameter:

SI

Value:

0.8

Test group / Remarks:

2.5% sodium cyanate

Reference 3

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

disregarded due to major methodological deficiencies

Study period:

from 1992-03-12 to 1992-09-23

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

This test was not taken into account, as it is regarded as invalid (4 animals died in test group and also significant erythema was noted in the negative control group, so not allowing a conclusion with regard to this endpoint).

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1981

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

84/449/EEC

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

The Guinea Pig Maximization Test (1992) met the previous requirements before the entry into force of REACH. The GPMT is suitable and reliable to cover this endpoint. For this reason and for animal welfare reasons, no further in vivo study (LLNA test) needs to be performed.

Species:

guinea pig

Strain:

other: Pirbright White (Bor: DHPW)

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann GmbH, D-33176 Borchen, Germany
- Age at study initiation: Males 8 weeks, females 8 weeks
- Weight at study initiation: males 345 - 479 g, females 386 -453 g
- Housing: 1 animal per cage
- Diet (e.g. ad libitum): ad libitum (standard diet, ssniffG, special diet for guinea pigs)
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.0 -21.5 °C
- Humidity (%): 40-66 %
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 1994-05-03 To: 1994-06-02

Route:

intradermal

Vehicle:

physiological saline

Concentration / amount:

0.3 %, application volume 0.1 mL

Day(s)/duration:

On day 1

Adequacy of induction:

other: Maximum non-irritating concentration

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

20%, application volume: 1 mL

Day(s)/duration:

On day 8/ 48 hours

Adequacy of induction:

non-irritant substance, but skin pre-treated with 10% SDS

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

20%, application volume: 0.2 mL

Day(s)/duration:

On day 22/ 24 hours

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

Vehicle control group 1: 3 male, 3 female
Vehicle control group 2: 3 male, 3 female
Test substance group 1: 5 male, 5 female

Details on study design:

RANGE FINDING TESTS:
In preliminary tests, the maximum non-irritating concentration for the intradermal concentration for the epidermal application during the induction phase as well as a non-irritating concentration for epidermal application during the challenge phase were determined.

MAIN STUDY
A. INDUCTION EXPOSURE (intradermal)
- No. of exposures: 6 (- 2 x Freund complete adjuvant(FCA)/physiological saline solution (1:1)
- 2 x test substance
- 2 x test substance/FCA (1.1))
- Test groups: application day: 1
- Control group: Identical treatment, however the vehicle was used instead of the test substance.
- Concentrations: 0.3 %

B. INDUCTION EXPOSURE (epidermal)
- No. of exposures: 1
- Exposure period: day 8
- Test groups: Treatment on day 7 with 10% solution of sodium lauryl sulfate in water, day 8 test substance
- Control group: Identical treatement, however the vehicle was used instead of the test substance.
- Site: Scapular area
- Frequency of applications: once on day 8
- Duration: 48 h
- Concentrations: 20 %

B. CHALLENGE EXPOSURE
- No. of exposures: 2
- Day(s) of challenge: day 22
- Exposure period: 24 h
- Test groups: as the result of the first challenge was unequivocal a second challenge was not performed
- Control group: The animals of the control group were treated like the animals of the test substance group.
- Site: right flank (test substance), left flank (vehicle)
- Concentrations: 20 %
- Evaluation (hr after challenge): 24 and 48 h

Challenge controls:

yes

Positive control substance(s):

no

Positive control results:

no positive control

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

20 %

No. with + reactions:

3

Total no. in group:

6

Clinical observations:

4 animals died

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

20 %

No. with + reactions:

3

Total no. in group:

6

Clinical observations:

4 animal died

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

20 %

No. with + reactions:

1

Total no. in group:

6

Clinical observations:

one animal with erythema

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

20 %

No. with + reactions:

1

Total no. in group:

6

Clinical observations:

one animal with erythema

Following epidermal challenge, 3 of 6 guinea pigs reacted with very slight to well defined erythema and one of these animals also with slight edema at the exposed skin. One of the control animals also showed a very slight erythema. During the induction period 4 of 10 guinea pigs died within 48 hours after epidermal application because of systemic toxicity of the test substance.

Interpretation of results:

study cannot be used for classification

Conclusions:

The test item analogue, sodium cyanate, has sensitizing properties on the skin of guinea pig (Maximisation Test).

Executive summary:

In a dermal sensitization study with the test item analogue sodium cyanate in physiological saline solution, 8 week old Pirbright White (Bor: DHPW) guinea pigs (5/sex) were tested using the method of Magnusson and Kligmann. Following epidermal challenge, 3 of 6 guinea pigs reacted with very slight to well defined erythema and one of these animals also with slight edema at the exposed skin. One of the control animals also showed a very slight erythema. During the induction period 4 of 10 guinea pigs died within 48 hours after epidermal application because of systemic toxicity of the test substance.

This study does not allow a final conclusion with regard to skin sensitising properties.

Reference 4

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

from 1994-02-24 to 1994-07-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Version / remarks:

92/32/EEC

Deviations:

no

GLP compliance:

yes

Type of study:

Buehler test

Justification for non-LLNA method:

The Buehler Test (1994) met the previous requirements before the entry into force of REACH. The Buehler Test is suitable and reliable to cover this endpoint. For this reason and for animal welfare reasons, no further in vivo study (LLNA test) needs to be performed.

Species:

guinea pig

Strain:

other: Hsd/Win: DH

Sex:

male/female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann GmbH, D-33176 Borchen, Germany
- Age at study initiation: Males 9 weeks, females 9 weeks
- Weight at study initiation: males 455-520 g, females 405-469 g
- Housing: 1 animal per cage
- Diet (e.g. ad libitum): ad libitum (standard diet, ssniffG, special diet for guinea pigs)
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-20°C
- Humidity (%): 51-65 %
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 1994-05-03 To: 1994-06-02

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

50%, application volume: 0.5 mL

Day(s)/duration:

On day 1, 8 and 15/ 6 hours

Adequacy of induction:

other: In a preliminary test no primary irritation of the test substance was observed.

Concentration / amount:

Induction: 50 %, application volume 0.5 mL
Challenge: 0.50 %, application volume 0.5 mL

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

physiological saline

Concentration / amount:

0.50%, application volume: 0.5 mL

Day(s)/duration:

On day 29/ 6 hours

Adequacy of challenge:

highest non-irritant concentration

No. of animals per dose:

Vehicle control group 1: 5 male, 5 female
Vehicle control group 2: 5 male, 5 female
Test substance group 1: 10 male, 10 female

Details on study design:

RANGE FINDING TESTS:
In a preliminary test no primary irritation of the test substance was observed.

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 3
- Exposure period: 15 days
- Test groups: application days: 1,8 and 15
- Control group: Identical treatment, however the vehicle was used instead of the test substance.
- Site: 3x3 cm of the left flank
- Frequency of applications: on day 1, 8 and 15
- Duration: 6 h
- Concentrations: 50 %

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: day 29
- Exposure period: 6 h
- Test groups: as the result of the first challenge was unequivocal a second challenge was not performed
- Control group: The animals of the control group were treated like the animals of the test substance group.
- Site: right flank (test substance), left flank (vehicle)
- Concentrations: 0.50 %
- Evaluation (hr after challenge): 24 and 48 h

Challenge controls:

yes

Positive control substance(s):

no

Positive control results:

no positive control

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

test chemical

Dose level:

0.5%

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no adverse effects

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

test chemical

Dose level:

0.5 %

No. with + reactions:

0

Total no. in group:

20

Clinical observations:

no adverse effects

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

negative control

Dose level:

0.5 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no adverse effects

Key result

Reading:

2nd reading

Hours after challenge:

48

Group:

negative control

Dose level:

0.5 %

No. with + reactions:

0

Total no. in group:

10

Clinical observations:

no adverse effects

No systemic toxic effects were observed. The general condition and body weight gain of the animals were not affected.

Interpretation of results:

GHS criteria not met

Conclusions:

The test item analogue, sodium cyanate, has no sensitizing properties on the skin of guinea pig (Buehler Test).

Executive summary:

In a dermal sensitization study with the test item analogue sodium cyanate in physiological saline solution, 9 weeks old Hsd/Win: DH guinea pigs (10/sex) were tested using the method of Buehler. Following epidermal challenge neither treated nor control animals showed erythema or edema. No systemic toxic effects were observed. The general condition and body weight gain of the animals were not affected. In this study, sodium cyanate is not a dermal sensitizer.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

No study is available to investigate the skin sensitization potential of the test item potassium cyanate. However, suitable and reliable studies with the test item analogue sodium cyanate are available which are considered to fulfill the requirements of REACH Annex VII, section 8.3.

In aqueous solution cyanate salts dissociate very quickly to cyanate ion and the respective alkali metal ion. It is not expected that Na+ or K+ contribute to the skin sensitizing potential. Sodium cyanate was shown to have no sensitisation potential (non-sensitizer) in the Local Lymph Node Assay in concentrations up to 10 % (maxium solubility). This result is supported by a Buehler Test with sodium cyanate (not sensitising). A third test showed sensitizing potential. However this test was not taken into account, as it is regarded as invalid (4 animals died in test group and also significant erythema was noted in the negative control group, so not allowing a conclusion with regard to this endpoint).

Key Study

Local Lymph Node Assay according to OECD 429 and Commission Regulation (EC) No 440/2008 of 30 May 2008, B.42 was performed with CBA/CaOlaHsd mice. The aim of this study was to determine the skin sensitisation potential of the test item analogue, sodium cyanate, following dermal exposure in the Local Lymph Node Assay. The test item was a white solid; vehicle compatibility was verified in a Preliminary Compatibility Test with Acetone: Olive oil 4:1 mixture (AOO), N,N-dimethylformamide, Propylene glycol, Dimethyl sulphoxide and 1 (w/v) % Pluronic. The test item was insoluble in first – fourth solvents. The suitable vehicle was 1 (w/v) % Pluronic. The maximum available concentration was 10% in this vehicle. Pluronic PE9200 is a surfactant, which ensures that 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. A Preliminary Irritation/Toxicity test was performed with the test item at concentrations of 10 % and 5 % in the selected vehicle. The 10 % concentration was considered acceptable as the maximum concentration in the main assay. In the main assay twenty female CBA/CaOlaHsd mice were allocated to five groups of four animals each:

- three groups received the appropriate formulation of test item analogue at concentrations of 10 %, 5 % and 2.5 %,

- the negative control group received the vehicle (1 % Pluronic),

- the positive control group received 25 (w/v) % HCA in relevant vehicle. The test item solutions were applied on the dorsal surface of ears of experimental animals (25 l/ear) for three consecutive days (Days 1, 2 and 3). There was no treatment on Days 4, 5 and 6. On Day 6, the cell proliferation in the local lymph nodes was measured by incorporation of tritiated methyl thymidine (3HTdR) and the values obtained were used to calculate stimulation indices (SI). No mortality or systemic clinical signs were observed during the study. No treatment related effect on the body weights was observed. No signs of irritation or other cutaneous effect were observed in any of the treated groups. No significant lymphoproliferative response (SI 3) of test item analogue 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. No dose-response to treatment was observed. α-Hexylcinnamaldehyde (25 (w/v) % dissolved in 1% Pluronic) was used as the positive control to demonstrate the appropriate performance of the assay. A significant lymphoproliferative response (stimulation index value of 8.9) was noted for the positive control chemical, this result confirmed the validity of the assay.

The test item analogue, sodium cyanate, is not considered to be a skin sensitizer under the test conditions chosen.

Supporting study

In a dermal sensitization study with the test item analogue, sodium cyanate, in physiological saline solution, 9 weeks old Hsd/Win: DH guinea pigs (10/sex) were tested using the method of Buehler. For induction the animals were exposed epidermally (occlusive patch, 24 h) with a concentration of 50 %. The challenge was conducted twice by exposure 0.5 % sodium cyanate in physiological saline (occlusive patch, 6 h). Following epidermal challenge neither treated nor control animals showed erythema or edema. No systemic toxic effects were observed. The general condition and body weight gain of the animals were not affected. In this study, sodium cyanate is not a dermal sensitizer.

 

Disregarded Study

In a dermal sensitization study with the test item analogue, sodium cyanate, in physiological saline solution, 8 week old Pirbright White (Bor: DHPW) guinea pigs (5/sex) were tested using the method of Magnusson and Kligmann. Following epidermal challenge, 3 of 6 guinea pigs reacted with very slight to well defined erythema and one of these animals also with slight edema at the exposed skin. One of the control animals also showed a very slight erythema. During the induction period 4 of 10 guinea pigs died within 48 hours after epidermal application because of systemic toxicity of the test substance. This study does not allow a final conclusion with regard to skin sensitising properties.

Conclusion

Based on the applied read-across approach the test item potassium cyanate is not considered to be a skin sensitiser.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Classification, Labelling, and Packaging Regulation (EC) No 1272/2008

Based on the available experimental data, the test item is not considered to be classified for skin sensitisation under Regulation (EC) No 1272/2008, as amended for the seventeenth time in Regulation (EU) 2021/849.