Potassium cyanate

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

2.96 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

25

Dose descriptor starting point:

NOAEL

Value:

60 mg/kg bw/day

Modified dose descriptor starting point:

NOAEC

Value:

74 mg/m³

Explanation for the modification of the dose descriptor starting point:

Using a conservative approach, a worker DNEL (long-term inhalation exposure) is derived.

Relevant dose descriptor (NOAEL): 60 mg/kg bw/day

Standard respiratory volume, human (sRVhuman) for 8 h per person (70 kg): 6.7 m³

Standard respiratory volume of the rat (sRVrat) for 8 hours: 0.38 m³/kg bw

Worker respiratory volume (wRV) for 8 hours with light physical activity per person: 10 m³

Oral absorption of the rat/ inhalation absorption of humans (ABS oral-rat / ABS inh-human): 1/2 (default)

Correction for difference between human and experimental exposure conditions: 7 d rat/5 d worker

Corrected NOAEC (inhalation) for workers:

NOAEC_corr = NOAEL_oral x 1/0.38 m³/kg bw/day x 6.7 m³/10m³ x 7d/5d x ABS_oral/ABS_inh

NOAEC_corr = 60 mg/kg bw/day x (1/0.38 m³/kg bw/day) x (6.7 m³/10 m³) x (7 days/ 5 days) x 0.5 

NOAEC_corr = 74 mg/m³

AF for dose response relationship:

1

Justification:

The dose response relationship is considered unremarkable, therefore no additional factor is used.

AF for differences in duration of exposure:

2

Justification:

The default factor for the differences between sub-chronic and chronic exposure duration is used.

AF for interspecies differences (allometric scaling):

1

Justification:

No allometric scaling factor is applied because an oral-to-inhalation route extrapolation is performed

AF for other interspecies differences:

2.5

Justification:

Recommended AF for other interspecies differences.

AF for intraspecies differences:

5

Justification:

The default value for the relatively homogenous group "worker" is used.

AF for the quality of the whole database:

1

Justification:

The quality of the whole data base is considered to be sufficient and uncritical.

AF for remaining uncertainties:

1

Justification:

The approach used for DNEL derivation is conservative. No further assessment factors are required.

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

8.9 mg/m³

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

3

DNEL extrapolated from long term DNEL

Local effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

3.36 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

100

Dose descriptor starting point:

NOAEL

Value:

60 mg/kg bw/day

Modified dose descriptor starting point:

NOAEL

Value:

336 mg/kg bw/day

Explanation for the modification of the dose descriptor starting point:

Using a conservative approach, a worker DNEL (long-term dermal exposure) is derived. Based on the physico-chemical properties of potassium cyanate especially its high hydrophilicity (log Kow: <0.3 and water solubility: 750 g/L) dermal absorption is considered to be 25% of oral absorption.

Correction for difference between human and experimental exposure conditions: 7 d rat/5 d worker

Corrected NOAEL (dermal) for workers:

NOAEL_corr = NOAEL_oral x 7d/5d x ABS_oral/ABS_dermal

NOAEL_corr = 60 mg/kg bw/day x 1.4 x 4

NOAEL_corr = 336 mg/kg bw/day

AF for dose response relationship:

1

Justification:

The dose response relationship is considered unremarkable, therefore no additional factor is used.

AF for differences in duration of exposure:

2

Justification:

The default factor for the differences between sub-chronic and chronic exposure duration is used.

AF for interspecies differences (allometric scaling):

4

Justification:

The default allometric scaling factor for the differences between rats and humans is used.

AF for other interspecies differences:

2.5

Justification:

Recommended AF for other interspecies differences.

AF for intraspecies differences:

5

Justification:

The default value for the relatively homogenous group "worker" is used.

AF for the quality of the whole database:

1

Justification:

The quality of the whole data base is considered to be sufficient and uncritical.

AF for remaining uncertainties:

1

Justification:

The approach used for DNEL derivation is conservative. No further assessment factors are required.

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

low hazard (no threshold derived)

Additional information - workers

General

Long-term DNELs were derived from data of sodium cyanate (read across). No adjustment regarding the different molecular weights of the two substances was made. In the case of potassium cyanate the DNELs would change by a factor of 1.25. Thus, the DNELs derived represent worst case assumptions.

DNEL derivation for the substance potassium cyanate is performed under consideration of the recommendations of ECHA. In view of the data used for evaluation, the "quality of whole database factors" and "dose-response factors" are considered to amount each to a value of 1, and are thus not shown in the calculations presented below.  

 

Workers – Hazard via inhalation route  

 

Long term systemic inhalation DNEL, worker

 

Calculation of dose descriptor  

Step 1: Selection of the relevant dose descriptor (starting point):

For risk characterisation a inhalation NOAEC was derived by route to route extrapolation. The oral NOAEL of 50 mg/kg bw/day, obtained from chronic repeated dose toxicity testing in dogs by Cerami, A (1973), was considered as key value for the chemical safety assessment and therefore, most relevant starting point.  

Step 2: Modification into a correct starting point:

In a first step the oral NOAEL was transferred to humans with a factor of 1.4 for allometric scaling from dogs. For worker a NOEC long-term, inhalation was calculated assuming 70 kg per person, 8h light activity (10 m³ breathing volume), 50 % absorption via oral routes and 100 % absorption via inhalatory routes.   NOEC (Worker)inhalation = 50 mg/kg bw/day * 1/1.4 *70 kg * 1/10 m³ * 50%Abs, (oral) / 100 % Abs, (inhal) =125 mg/m³  

Step 3: Use of assessment factors: 12.5

Interspecies: no allometric scaling factor is applied because an oral-to-inhalation route extrapolation is performed.

Interspecies AF, remaining differences: 2.5

Intraspecies AF (worker): 5  

In conclusion the long term systemic inhalation DNEL workers was calculated to be 10 mg/m³ bw/day.

 

Short term inhalation DNEL, worker

No study for acute inhalation toxicity is availabe. As the substance is classified as acute toxic (oral) cat 4 a acute inhalation tixucuty can not be excluded and a cute inhalation DNEL is derived. The acute inhalation DNEL was based on long-term inhalation DNEL. The acute inhalation DNEL was calculated as 3 times the value of the corresponding long-term DNEL (ECHA CSR R.8, 2012). Thus, worker DNEL acute inhalation = 3 x 10 mg/m³/day = 30 mg/m³.

 

Local effects skin irritation/corrosion: 

Potassium cyanate is not classified for skin irritation and skin sensitisation according to Regulation (EC) No 1272/2008 (CLP) based on the available experimental data. Therefore, no qualitative assessment is conducted.  

 

Eye irritation: Potassium cyanate is classified for eye irritation as cat. 2, based on the results of the eye irritation studies available. A qualitative risk assessment is conducted and the substance assigned to the low hazard band.

 

Workers – Hazard via dermal route  

 

Long term systemic dermal DNEL, worker

 

Calculation of dose descriptor  

 

Step 1: Selection of the relevant dose descriptor (starting point):

For risk characterisation a dermal NOAEL was derived by route to route extrapolation. The oral NOAEL of 50 mg/kg bw/day, obtained from chronic repeated dose oral toxicity testing in dogs by Cerami, A (1973), was considered as key value for the chemical safety assessment and therefore, most relevant starting point.  

 

Step 2: Modification into a correct starting point:

Based on the physical chemical properties of the substance (inorganic ionic substance, with high water solubility) a dermal absorption rate of 25 % through skin was deduced. In conclusion, dermal NOAEL = oral NOAEL x [ABS oral dog /ABS dermal human] = 50 mg/kg bw/day x (100/25) = 200 mg/kg bw/d.  

 

Step 3: Use of assessment factors: 17 .5

Interspecies AF, allometric scaling (dog to human): 1.4

Interspecies AF, remaining differences: 2.5

Intraspecies AF (worker): 5

Exposure duration AF (chronic exposure period): 1  

In conclusion the long term systemic dermal DNEL workers were calculated to be 11.43 mg/kg bw/day.  

 

Acute short term dermal DNEL, worker

The test material is not classified and labelled for acute dermal toxicity, according to Regulation (EC) No 1272/2008 (CLP). Thus, in accordance with “Guidance on information requirements and chemical safety assessment chapter R8: Characterisation of dose (concentration)- response for human health” no DNEL is required.  

 

References (not included as endpoint study record)  

- ECHA (2012). Guidance on information requirements and chemical safety assessment. Chapter R.8: Characterisation of dose [concentration]-response for human health. Version 2.1 ECHA-2010 -G-19 –EN.  

- ECHA (2017). Guidance on information requirements and chemical safety assessment.Chapter R.7.12: Endpoint specific guidance: Guidance on Toxicokinetics. Version 3.0. ECHA-17-G-11-EN.  

- ECHA (2012) Practical Guide 15: How to undertake a qualitative human health assessment and document it in a chemical safety report, November 2012.  

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - General Population

General

 

General population is not intended to be exposed to Potassium cyanate via inhalation or dermal route. Therefore, no DNEL (long-term, inhalation and dermal exposure) is derived for general population. As Potassium cyanate has no bioaccumulation potential no risk assessment for secondary poisoning is required for the general population.

 

References

(not included as endpoint study record)

- ECHA (2012) Guidance on information requirements and chemical safety assessment. Chapter R.8: Characterisation of dose [concentration]-response for human health. Version 2.1 ECHA-2010-G-19-EN.

- ECHA (2011) Guidance on information requirements and chemical safety assessment. Part B: Hazard assessment. Version 2 ECHA-11-G-16-EN