Potassium thiocyanate

Endpoint summary

Description of key information

The key value from acute oral toxicity is derived from a study with ammonium thiocyanate in Japanese quails (OECD 401, GLP) resulting to a LD50 508 mg/kg bw, which equals to 649 mg/kg bw when based on KSCN.
In an acute dermal toxicity study with potassium thiocyanate no mortalities occurred and the LD50 is >2000 mg/kg bw.
An acute inhalation study is not available but inhalation is not a likely route of exposure due to the low vapour pressure, hygroscopic properties of the substance and the way of use.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

08 December 1998 - 30 December 1998

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was performed according to internationally accepted guidelines and under GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

no

Species:

other: Japanese quail (Coturnix coturnix faponica)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: H. und E. Kilberich, Geesdorf, Germany
- Age at study initiation: 8 weeks
- Weight at study initiation: males : 182 - 254 g of treatment females: 185 - 234 g. The weight of one male was slightly outside the range given in the protocol. This deviation was considered not to have affected the study integrity.
- Fasting period before study: Prior to dosing food was withheld for If to 20 hours.
- Housing: Individual housing in stainless steel wire mesh, battery type cages (dimensions: 16 crn x 27 cm and a height of 20-23 cm).
- Diet (e.g. ad libitum): Free access to a standard commercial avian diet, (= basal diet) Special Diet Services, Witham, Essex, United Kingdom.
- Water (e.g. ad libitum): Free access to tap water.
- Acclimation period: 15 days under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15.5-23
- Humidity (%): 56-68
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 8/16

IN-LIFE DATES: 16 December 1998 - 30 December 1998

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

VEHICLE
- Concentration in vehicle: Concentration of test substance in vehicle was varied to allow constant dosage volume in terms of ml/kg body weight.
- Amount of vehicle (if gavage): doding volume was maximally 5 ml/kg
- Justification for choice of vehicle: The vehicle was selected based on trial formulations performed at NOTOX and/or test substance data supplied by the sponsor.
- Lot/batch no. (if required): not applicable
- Purity: not applicable

MAXIMUM DOSE VOLUME APPLIED: 5 ml/kg

DOSAGE PREPARATION (if unusual): The test formulation was homogenised to a visually acceptable level by stirring. The test formulation was dosed within 2 hours after preparation.

Doses:

191, 343, 617, 1111 and 2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
Mortality:
On day of dosing: continuously during the first 1 to 2 hours after dosing, and subsequently every 2 hours (at least three times). During remainder of study period: twice a day.
Clinical signs:
On day of dosing: continuously during the first 1 to 2 hours after dosing, and subsequently every 2 hours (at least three times). Durjng remainder of study period: once a day. All signs of reaction to treatment were recorded and graded according to fixed scales (specified in the report). The time of onset and duration was recorded. Mortality and clinical signs were recorded in the computer.
Body weights:
Day before dosing (when capsules are used), day 1 (day of dosing), day 8, day 15 and at death (from day 2 onwards).
- Necropsy of survivors performed: yes, necropsy and descriptions of all internal macroscopic abnormalities were recorded. Gross necropsies included general inspection of the gastrointestinal tract, liver , kidney, heart and spleen.
- Other examinations performed:
Food consumption:
Food consumption was monitored from days 1-4, 4-8, 8-11 and 11-15.

Statistics:

The LD50 value, the associated 95% confidence limits and the slope of the dose-response line were calculated in terms of the quantity of active ingredient or total formulation (as appropriate) per unit body weight. The LD50 value was calculated using the Maximum Likelihood method (Finney, D.G.,
Probit Analyses, 3rd Edition, London, Cambridge University Press, 1971). Group means were calculated for continuous data.
The following statistical methods were used to analyse body weights and food consumption:
- Since variables were assumed to follow a normal distribution, the Dunnett test (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control groups for each sex.
Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations may have been rounded off before printing. Therefore, for example, two groups may display the same printed means for a given parameter, yet display different test statistics values.
The test is invalid if more than 10% o f the birds in the control group die. No compound-related, observable toxic effects should be recorded in the lowest test concentration.

Preliminary study:

Treatment:
The test substance was administered as a single dose by oral gavage using water {milli-U) as a vehicle at dose concentrations of 20, 200 and 2000 mg/kg body weight. The dose volume was 5 ml/kg body weight. One male and one female were used per dose group.
Observations:
Birds were checked for mortality, clinical signs and body weights in a similar way as described for the main study with the exception that the study
continued for 8 days.
Results:
The two birds of the 2000 mg/kg group died within one hour after dosing. Clinical signs observed were clonic spasms, tremors of the head, ventrolateral recumbency, hunched posture, uncoordinated movements, breathing abnormalities, fluid faeces and ptosis in the highest dosage group prior to death. Fluid faeces was noted at 200 mg/kg and 20 mg/kg. No effects on body weights were found in the surviving birds.
Conclusions:
Based on these results it was decjded to conduct a full study with dose levels selected to be 0, 191, 343, 617, 1111 and 2000 mg/kg body weight.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

508 mg/kg bw

95% CL:

349 - 693

Sex:

female

Dose descriptor:

LD50

Effect level:

508 mg/kg bw

95% CL:

285 - 790

Sex:

male

Dose descriptor:

LD50

Effect level:

508 mg/kg bw

95% CL:

285 - 790

Mortality:

None of the animals died in group 1-3 (0, 191, 343 mg/kg bw) and all animals died in groups 4-6 (617, 1111, 2000 mg/kg bw) .All deaths of group 4 (617 mg/kg) were recorded within 5 hours after dosing except for one male, which was found dead on day 2 after treatment. Four deaths of group 5 (1111 mg/kg) were observed within 3 hours, the remaining deaths of this group and all of group 6 (2000 mg/kg) were recorded within 1 hour after dosing.

Clinical signs:

other: The following clinical findings were noted: 0 mg/kg: Fluid faeces until 3 hours after dosing in all birds. 191 mg/kg: Fluid faeces until 5 hours after dosing in all birds. 343 mg/kg : Fluid faeces until day 2 in all birds. Uncoordinated movements, letharg

Gross pathology:

0 mg/kg: No findings noted.
191 mg/kg: No findings noted.
343 mg/kg: No findings noted.
617 mg/kg: Haemorrhages in the intestines, swollen andlor dark red liver, a dark red spleen and a detached cuticle of the
stomach were noted among the birds.
1111 mg/kg: Haemorrhages in the intestines, swollen andlor dark red liver, and detached cuticles of the stomach were noted
among the birds.
2000 mg/kg: Haemorrhages in the intestines, swollen andlor dark red liver and detached cuticles of the stomach were noted among
the birds.

The findings in the dosage groups of 617 mg/kg and above were considered to be adverse effects of treatment with the test substance.

Other findings:

Mean food intake was statistically significantly decreased far both sexes in the 343 mg/kg group after 4 days of treatment when comparing with the control group. This was considered to be an adverse effect of administration of ammonium thiocyanate. Due to death of the birds, non-relevant statistical significant differences were obtained for the higher dose groups. No effect on mean food consumption was seen at 191 mg/kg.

Interpretation of results:

Category 4 based on GHS criteria

Remarks:

Migrated information

Conclusions:

Under the conditions of this study, the oral LD values of ammoniumthiocyanate in Japanese quail for the sexes combined was established as 508
mg/kg body weight with 95% confidence limits being 349 - 693 mg/kg and the slope of the dose-response curve 3.11. For the individual sexes the LD50 values were also established to be 508 mg/kg body weight with the 95% confidence intervals being 285 - 790 mg/kg and the slope being 2.45. The no observed effect level (NOEL) in this study was 191 mg/kg body weight.

Executive summary:

This study was performed to assess the acute thiocyanate to the Japanese quail when administered as a single oral dose. The study carried out was based on the OECD Guideline No. 401 and on the EPA FIFRA Ref. No. 71-1, EPA TSCA Par. 797.2175, EPA OPPTS Par. 850.2100 Guidelines, with the exception that the study was performed with Japanese quails.

Treatment

Ammonium thiocyanate was administered by oral gavage, using water (Milli-U) as a vehicle, to five birds of each sex at 191, 343, 617, 1111 or 2000 mg/kg body weight. A control group of five birds of each sex was dosed with vehicle (5 ml/kg). Birds were observed at periodic intervals on the day of dosing and daily thereafter; body weight was determined at start of the study (day 1), day 8 and day 15; food consumption was measured from days 1-4, 4-8, 8-11 and 11-15. Macroscopic post-mortem examination was performed at termination (day 15).

Results

0 mg/kg: 1) Fluid faeces.

191 mg/kg: 1) Fluid faeces.

343 mg/kg: 1) Fluid faeces, uncoordinated movements, lethargy, clonic spasms, abnormal posture of the head, ventro-lateral recumbency, hunched posture, breathing abnormalities or ptosis were seen among the birds.

2) Reduced food consumption during 4 days after dosing.

1111 mg/kg 1) All birds died within 5 hours after dosing, except for one male which was found dead on day 2. 2 )Clinical signs noted were fluid or red faeces, uncoordinated movements, lethargy, clonic spasms, abnormal posture of the head, tremors of the head or wing, ventro-lateral recumbency, hunched posture, breathing abnormalities and ptosis. 3) Examination post-mortem revealed haemorrhages in the intestines, swollen andlor dark red liver, dark red spleen and a detached cuticle of the stomach.

2000 mg/kg

1) All birds died within 1 hour post-dosing.

2) Clinical signs noted were fluid faeces, uncoordinated movements, lethargy, clonit spasms, tremors or abnormal posture of the head, ventro-lateral recumbency, hunched posture, breathing abnormalities and ptosis.

3) Examination post-mortem revealed haemorrhages in the intestines, swollen andlor dark red liver and detached cuticles of the stomach.

Conclusion

Under the conditions of this study, the oral LD50 values of ammonium thiocyanate in Japanese quail was established as 508 mg/kg body weight with 95% confidence limits being 349 - 693 mg/kg and the slope of the dose-response curve 3.11. For the individual sexes the LD50 values were also established to be 508 mg/kg body weight with the 95% confidence intervals being 285 - 790 mg/kg and the slope being 2.45. The no observed effect level (NOEL) in this study was 191 mg/kg body weight.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

649 mg/kg bw

Quality of whole database:

The database show consistent results. Although the quail is not the preferred for this endpoint, all other data from lower quality data sources indicate the same level of toxicity.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 August 2003 - 20 August 2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is performed according to internationally accepted guidelines and acocrding to GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Qualifier:

according to guideline

Guideline:

other: Japanese Ministry of Agriculture, Forestry and Fisheries (.JMAFF), 12 Nousan, Notification No 8147, November 2000, including the most recent partial revisions.

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany.
- Age at study initiation: ±10 weeks
- Weight at study initiation: males 340 g, females 238 g
- Fasting period before study: not applicable
- Housing: Individually housed in labelled Macrolon cages (type III, height 15 cm.) containing purified sawdust as bedding material (SAWI, Jelu Werk, Rosenberg, Germany). Certificates of analysis were examined and then retained in the NOTOX archives.
- Diet (e.g. ad libitum): Free access to standard pelleted laboratory animal diet (from Altromin (code VRF 1), Lage, Germany). Certificates of analysis were examined and then retained in the NOTOX archives.
- Water (e.g. ad libitum): Free access to tap·water. Certificates of quarterly analysis were examined and then retained in the NOTOX archives.
- Acclimation period: at least 5 days before start of treatment under laboratory conditions.

ENVIRONMENTAL CONDITIONS
- Temperature (°C):19.1-24.5
- Humidity (%): 44-79
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: 06 August 2003 - 20 August 2003

Type of coverage:

occlusive

Vehicle:

water

Details on dermal exposure:

TEST SITE
- Area of exposure: back
- % coverage: 10%
- Type of wrap if used: The formulation was held in contact with the skin with a dressing, consisting of a surgical gauze patch (Surgy 1D)*, successively covered with aluminium foil and Coban flexible bandage. A piece of Micropore tape was additionally used for fixation of the bandages in females only.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): after dressings were removed and the skin cleaned of residual test substance using water
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 2000 mg/kg (10 ml/kg) body weight
- Concentration (if solution): variable
- Constant volume or concentration used: constant volume
- For solids, paste formed: no

VEHICLE
- Amount(s) applied (volume or weight with unit): variable
- Concentration (if solution): variable
- Lot/batch no. (if required): not applicable
- Purity: not applicable

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

Mortality/Viability: Twice daily

Body weights: Days 1 (pre-administration), 8 and 15

Clinical signs:
At periodic intervals on the day of dosing (day 1) and once daily
thereafter, until day 15. The time of onset, degree and duration
were recorded and the symptoms graded according to fixed scales:
Maximum grade 4: grading slight (1) to very severe (4)
Maximum grade 3: grading slight (1) to severe (3)
Maximum grade 1: presence is scored (1).

Necropsy
At the end of the observation period, all animals were sacrificed by asphyxiation using an oxygen/carbon dioxide procedure and subjected to necropsy. Descriptions of all internal macroscopic abnormalities were recorded.

Statistics:

No statistical analysis was performed.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

No mortality occurred.

Clinical signs:

other: Chromodacryorrhoea was noted in all animals. All animals had recovered from the symptoms between days 2 and 3. Erythema, necrosis, scales, scabs were seen in the treated skin-area of the animals during the observation period.

Gross pathology:

No abnormalities were found at macroscopic post mortem examination of the animals.

Other findings:

None

Interpretation of results:

study cannot be used for classification

Remarks:

Migrated information

Conclusions:

The dermal LD50 value of KSCN (POTASSIUM THIOCYANATE) in Wistar rats was established to exceed 2000 mg/kg body weight. No significant signs of toxicity were observed at this dose level and therefore the test substance is not classified for acute dermal toxicicty.

Executive summary:

Assessment of acute dermal toxicity with KSCN (POTASSIUM THIOCYANATE) in the rat. The study was carried out based on the guidelines described in: Environmental Protection Agency (EPA): Health Effects Test Guidelines OPPTS 870.1200. "Acute Dermal Toxicity", EC Commission Directive 92/69/EEC, Part B.3, "Acute Toxicity-Dermal", OECD NoA02, "Acute Dermal Toxicity" and JMAFF: Japanese Test Guidelines.

KSCN (POTASSIUM THIOCYANATE) was administered to five Wistar rats of each sex by dermal application at 2000 mg/kg body weight for 24 hours. Animals were subjected to daily observations and weekly determination of body weight. Macroscopic examination was performed after terminal sacrifice (day 15).

No mortality occurred. Chromodacryorrhoea was noted in all animals. All animals had recovered from the symptoms between days 2 and 3.

Erythema, necrosis, scales, scabs were seen in the treated skin-area of the animals during the observation period. The changes noted in body weight gain in males and females were within the range expected for rats used in this type of study. No abnormalities were found at macroscopic post mortem examination of the animals.

The dermal LDso value of KSCN (POTASSIUM THIOCYANATE) in Wistar rats was established

to exceed 2000 mg/kg body weight.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

discriminating dose

Value:

2 000 mg/kg bw

Quality of whole database:

The study is GLP compliant and has Klimisch score 1

Additional information

Oral toxicity: For potassium thiocyanate a valid acute oral toxicity study is not available. However values from literature are all within the same range. In one study the LD50 in mice is 594.4 ± 27.0 mg/kg bw and the LD50 in rats is 854.1 ± 66.6 mg/kg bw. An LD50 of 590 mg/kg bw is also reported for mice in a table retrieved from RTECS. The key value from acute oral toxicity is derived from a study with ammonium thiocyanate in Japanese quails (OECD 401, GLP) resulting toan LD50 of 508 mg NH4SCN/kg bw. Calculated to KSCN this equals 649 mg KSCN/kg bw. Although this is not the standard species the value from this study is supported by values from literature: 500/720, 750 and 500 mg/kg bw in mouse rat and guinea pig, respectively. And also by values reported for sodium thiocyanate in literature are with the same range. In one study the LD50 in mice is 598.4 ± 18.3 mg/kg bw and the LD50 in rats is 764.7 ± 50.9 mg/kg bw. In a table retrieved from RTECS values rats are reported from 232-1180 mg/kg bw, for mice 360-809 mg/kg bw and one for domestic animal of 520 mg/kg bw.

 

Dermal toxicity:

In an acute dermal toxicity study with potassium thiocyanate no mortalities occurred and the LD50 was established as >2000 mg/kg bw. This fits with the notion that dermal absorption of salts that are fully dissociated in aqueous solution is slow.

 

Inhalation toxicity:

Only available information is an LC50 > 100 mg/m3 for ammonium thiocyanate listed in RTECS of unassignable validity, and a level that is not conclusive for classification. Other information on sodium thiocyanate reports a LD50 of 232 mg/kg bw following intratracheal application.

There are no relevant data from acute inhalation toxicity studies. However, inhalation is not a likely route of exposure due to the very low vapour pressure (< 1.33 x 10-8 Pa for KSCN), hygroscopic properties of the substance and the way of use, generally involving aqueous solutions in which sodium thiocyanate is completely dissociated and thus will not lead to evaporation of thiocyanate ions.

 

Information on acute toxicity via other routes of application includes i.p., s.c. and i.v. in various species. All results indicate similar level of acute toxicity compared to oral, with only a generally somewhat lower LD50 level of around 100 mg/kg administration following direct i.v. administration. This indicates that oral absorption is complete, and that following absorption by any route the distribution over the extracellular volume is the same.

 

Potassium thiocyanate is a hygroscopic solid that does not contain aliphatic, alicyclic and aromatic hydrocarbons and in aqueous solutions does not decrease surface tension and therefore does not indicate a concern for aspiration hazard.

Justification for selection of acute toxicity – oral endpoint
Most valid study based on read-across.

Justification for selection of acute toxicity – inhalation endpoint
Low likelihood of exposures

Justification for selection of acute toxicity – dermal endpoint
Only available study

Justification for classification or non-classification

Based on weight of the evidence potassium thiocyanate is classified in GHS category IV for acute oral toxicity.

 

In an acute dermal toxicity study with potassium thiocyanate no mortalities occurred and the LD50 is >2000 mg/kg bw and based on this study there is no need for classification for acute dermal toxicity.

 

There is no data on inhalation toxicity. In view of limited likelihood of exposure no classification is indicated.

 

Thiocyanates are hygroscopic solids, do not contain aliphatic, alicyclic and aromatic hydrocarbons and in aqueous solutions do not decrease surface tension and therefore do not indicate a concern for aspiration hazard.