Potassium O-pentyl dithiocarbonate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge nitrification inhibition testing

Type of information:

other: published data

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

ISO 9509 (Toxicity test for assessing the inhibition of nitrification of activated sludge microorganisms)

Principles of method if other than guideline:

The influence of 28 nitrification inhibitors on denitrification of nitrate in soil was studied by determining the effects of different amounts of each inhibitor on the amounts of nitrate lost and the amounts of nitrite, N2O and N2 produced when soil samples were incubated anaerobically after treatment with nitrate or with nitrate and mannitol.

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

Nitrosomonas sp.

Details on inoculum:

Nitrosomonas
Scientific classification
Domain: Bacteria
Phylum: Proteobacteria
Class: Beta Proteobacteria
Order: Nitrosomonadales
Family: Nitrosomonadaceae
Genus: Nitrosomonas

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

NR

Test temperature:

20 to 30°C

pH:

6.0-9.0

Dissolved oxygen:

NR

Salinity:

NR

Nominal and measured concentrations:

10 g g–1 soil ,50 g g–1 soil ,100 g g–1 soil.

Reference substance (positive control):

no

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of nitrification rate

Remarks on result:

other: Potassium ethyl xanthate is a nitrification inhibitor that has a been observed to inhibit soil denitrification at concentrations around 50 ppm, but only in soils previously amended with mannitol to stimulate denitrifying activity

Details on results:

Potassium ethyl xanthate retarded denitrification when applied at the rate of 50 g g–1 soil to soil that had been amended with mannitol to promote microbial activity.
No inhibition of denitrification was observed when this compound was applied at the rate of 10 g g–1 soil, and enhancement of denitrification was observed when it was applied at the rate of 50 or 100 g g–1 soil.
The Potassium amyl xanthate (CAS No. 2720-73-2), the subject of this dossier) is expected to exhibit very similar toxicity to Potassium ethyl xanthate (CAS No. 140-89-6), which is also xanthate compound.. Comparable metabolism would occur.

The influence of 28 nitrification inhibitors on denitrification of nitrate in soil was studied by determining the effects of different amounts of each inhibitor on the amounts of nitrate lost and the amounts of nitrite, N2O and N2 produced when soil samples were incubated anaerobically after treatment with nitrate or with nitrate and mannitol.

The inhibitors used included nitrapyrin (N-Serve), etridiazole (Dwell), potassium azide, 2-amino-4-chloro-6-methylpyrimidine (AM), sulfathiazole (ST), 4-amino-1,2,4-triazole(ATC),2,4-diamino-6-trichloromethyl-s-triazine (CL-1580), potassium ethyl xanthate, guanylthiourea (ASU), 4-nitrobenzotrichloride, 4-mesylbenzotrichloride, sodium thiocarbonate (STC), phenylmercuric acetate (PMA), and dicyandiamide (DCD).Only one of the nitrification inhibitors studied (potassium azide) retarded denitrification when applied at the rate of 10 g g–1 soil, and only two (potassium azide and 2,4-diamino-6-trichloromethyl-s-triazine) inhibited denitrification when applied at the rate of 50 g g–1 soil. The other inhibitors either had no appreciable effect on denitrification, or enhanced denitrification, when applied at the rate of 10 or 50 g g–1 soil, enhancement being most marked with 3-mercapto-1,2,4-triazole. Seven of the inhibitors (potassium azide, sulfathiazole,potassium ethyl xanthate,sodium isopropyl xanthate, 4-nitrobenzotrichloride, sodium thiocarbonate, and phenylmercuric acetate) retarded denitrification when applied at the rate of 50 g g–1 soil to soil that had been amended with mannitol to promote microbial activity.Reports that nitrapyrin (N-Serve) and etridiazole (Dwell) inhibit denitrification when applied at rates as low as 0.5 g g–1 soil could not be confirmed. No inhibition of denitrification was observed when these compounds were applied at the rate of 10 g g–1 soil, and enhancement of denitrification was observed when they were applied at the rate of 50 or 100 g g–1 soil.

Validity criteria fulfilled:

yes

Conclusions:

Potassium ethyl xanthate is a nitrification inhibitor that has been observed to inhibit soil denitrification at EC50= 50 mg/l.
The Potassium amyl xanthate (CAS No. 2720-73-2), the subject of this dossier) is expected to exhibit very similar toxicity to Potassium ethyl xanthate (CAS No. 140-89-6), which is also xanthate compound.. Comparable metabolism would occur.

Executive summary:

Potassium ethyl xanthate retarded denitrification when applied at the rate of 50 g g–1 soil to soil that had been amended with mannitol to promote microbial activity. No inhibition of denitrification was observed when this compound was applied at the rate of 10 g g–1 soil, and enhancement of denitrification was observed when it was applied at the rate of 50 or 100 g g–1 soil.

The Potassium amyl xanthate (CAS No. 2720-73-2), the subject of this dossier) is expected to exhibit very similar toxicity to Potassium ethyl xanthate (CAS No. 140-89-6), which is also xanthate compound.. Comparable metabolism would occur.

Reference 2

Endpoint:

toxicity to microorganisms

Type of information:

other: published data

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline available

Principles of method if other than guideline:

The Microtox test for reduction of luminescence in Photobacterium phosphoreum was used. The test was carried out using the procedure described in the manual of the Beckman 2055 apparatus (1982).

GLP compliance:

no

Analytical monitoring:

not required

Vehicle:

no

Test organisms (species):

Photobacterium phosphoreum

Details on inoculum:

marine bacterium

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

15 min

Hardness:

90 mg CaCO3/L

Test temperature:

20 ± 1 °C

pH:

8.7 ± 0.2

Dissolved oxygen:

Not reported

Salinity:

Not reported

Nominal and measured concentrations:

The test was carried out in sealed flasks to prevent evaporation of CS2.
The medium contained major salts, urea, Ca-glycerophosphate, dextrose and trace elements. The complete composition of the test medium is given in Van Leeuwen and Maas, Environ. Pollution A37: 105-115 (1985).

Details on test conditions:

The test was carried out in sealed flasks to prevent evaporation of CS2.

Reference substance (positive control):

no

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

341 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: inhibition of bacterial luminescence

Remarks on result:

other: 95% C.I.: 260-448 mg/L

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

906.5 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Potassium amyl xanthate

Basis for effect:

other: inhibition of bacterial luminescence

Remarks on result:

other: On a molecular weight scaled basis, the EC50 would be 906.5 mg/l. (341 x 202.37) /76.13 =906.5 mg/l

Details on results:

Potassium amyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of potassium amyl xanthate.
On a molecular weight scaled basis, the EC50 would be 906.5 mg/l. (341 x 202.37) /76.13 =906.5 mg/l

This study reports a 15-min EC50 of 341 mg/L (carbon disulphide (CS2) for the marine bacterium Photobacterium phosphoreum based on the results of a Microtox test.

Validity criteria fulfilled:

yes

Conclusions:

The 15-min EC50 of CS2 for Photobacterium posphoreum luminescence was 341 mg/L.
Potassium amyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of potassium amyl xanthate.
On a molecular weight scaled basis, the EC50 would be 906.5 mg/l. (341 x 202.37) /76.13 =906.5 mg/l

Executive summary:

The 15-min EC50 of CS2 for Photobacterium posphoreum luminescence was 341 mg/L.

Potassium amyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of potassium amyl xanthate.

On a molecular weight scaled basis, the EC50 would be 906.5 mg/l. (341 x 202.37) /76.13 =906.5 mg/l

Reference 3

Endpoint:

activated sludge respiration inhibition testing

Type of information:

other: published data

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

other: A-Z test, Deutsches Einheidsverfahren DEV-L 9

Principles of method if other than guideline:

Measurement of oxygen consumption of activated sludge in a closed system to prevent evaporation of CS2.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

Mixed bacterial population (activated sludge).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

24 h

Hardness:

NR

Test temperature:

20 ± 1 °C

pH:

8.7 ± 0.2

Dissolved oxygen:

Not reported

Salinity:

Not reported

Details on test conditions:

not available

Reference substance (positive control):

not required

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

24 h

Dose descriptor:

EC10

Effect conc.:

4.6 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

24 h

Dose descriptor:

EC100

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

34.6 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Potassium amyl xanthate

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: On a molecular weight scaled basis, the EC50 would be 34.6mg/l. (13 x 202.37) /76.13 =34.6 mg/l

Duration:

24 h

Dose descriptor:

EC10

Effect conc.:

12.2 mg/L

Nominal / measured:

nominal

Conc. based on:

other: Potassium amyl xanthate

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: On a molecular weight scaled basis, the EC10 would be 12.2 mg/l. (4.6x 202.37) /76.13 =12.2 mg/l

Details on results:

Potassium amyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of potassium amyl xanthate.
On a molecular weight scaled basis, the EC50 would be 34.6mg/l. (13 x 202.37) /76.13 =34.6 mg/l
On a molecular weight scaled basis, the EC10 would be 12.2 mg/l. (4.6x 202.37) /76.13 =12.2 mg/l

.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 for inhibition of oxygen consumption in activated sludge by CS2 is 13 mg/L.
Potassium amyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of potassium amyl xanthate.
On a molecular weight scaled basis, the EC50 would be 34.6mg/l. (13 x 202.37) /76.13 =34.6 mg/l
On a molecular weight scaled basis, the EC10 would be 12.2 mg/l. (4.6x 202.37) /76.13 =12.2 mg/l

Executive summary:

The EC50 for inhibition of oxygen consumption in activated sludge by CS2 is 13 mg/L.

Potassium amyl xanthate readily decomposes to carbon disulphide, especially in the presence of moisture/water. Therefore, the health effects of carbon disulphide (CS2) need to be considered in the assessment of potassium amyl xanthate.

On a molecular weight scaled basis, the EC50 would be 34.6mg/l. (13 x 202.37) /76.13 =34.6 mg/l

On a molecular weight scaled basis, the EC10 would be 12.2 mg/l. (4.6x 202.37) /76.13 =12.2 mg/l

Reference 4

Endpoint:

toxicity to microorganisms

Type of information:

other: published data

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Justification for type of information:

According to the OECD SIDS document for potassium hydroxide (30 January 2002), a Klimisch 2 reliability score was assigned since the study was comparable to a guideline study with acceptable restrictions. However, the methodology used is not reliable. The Klimisch reliability score is therefore 3.

Qualifier:

equivalent or similar to guideline

Guideline:

other: Environment Canada EPS 1/RM/24: biological test method: toxicity test using luminescent bacteria

Principles of method if other than guideline:

Microtox Toxicity Analyser system, Microbics Corporation (Carlsbad CA). Test substance in added to cells suspensions and light readings are measured before and 15 minutes after sample addition. Light loss is proportional to toxicity of the sample, with 50% light loss being defined as the EC50.

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

- concentrations: 10,,20,30,40 mg/l
- Sampling method: 4g of test substance was extracted in 20 ml of saline. This sample was weigehed into 2% NaCl to make a 1% (10g/l) solution. This sample was diluted into a concentration range where a normal dose response was observed with LBT

Vehicle:

no

Test organisms (species):

Photobacterium phosphoreum

Details on inoculum:

- Laboratory culture:B-NRRL 11177
- Initial biomass concentration:50g/l

Test type:

other: closed test vial

Water media type:

saltwater

Limit test:

no

Total exposure duration:

15 min

Test temperature:

15°C

pH:

7.8

Dissolved oxygen:

9.1 mg/l

Salinity:

2% NaCl

Nominal and measured concentrations:

nominal concentrations: 10,,20,30,40 mg/l (recovery: 98-103%)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable):closed
- No. of organisms per vessel:10µl of cell suspension

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : reduction in light

Reference substance (positive control):

yes

Remarks:

sodium hypochlorite

Duration:

15 min

Dose descriptor:

EC50

Effect conc.:

22 mg/L

Nominal / measured:

estimated

Basis for effect:

other: light reduction

Remarks on result:

other: the luminiscent bacteria toxicity test gives following result: 15 minutes EC50 = 22 mg/L for photobacterium phosphoreum

Validity criteria fulfilled:

not specified

Conclusions:

The luminiscent bacteria toxicity test gives following result: 15 minutes EC50 = 22 mg/L for photobacterium phosphoreum.
Potassium Hydroxide is used in the manufacturing process for Potassium amyl xanthate and is present in the final product. Therefore, the health effects of Potassium Hydroxide need to be considered in the assessment of potassium amyl xanthate.

Description of key information

Potassium ethyl xanthate is a nitrification inhibitor that has been observed to inhibit soil denitrification at EC50= 50 mg/l.
The Potassium amyl xanthate (CAS No. 2720-73-2), the subject of this dossier) is expected to exhibit very similar toxicity to Potassium ethyl xanthate  (CAS No. 140-89-6), which is also xanthate compound.. Comparable metabolism would occur.

Key value for chemical safety assessment

EC50 for microorganisms:

50 mg/L

EC10 or NOEC for microorganisms:

10 mg/L

Additional information

Potassium ethyl xanthate is a nitrification inhibitor that has been observed to inhibit soil denitrification at EC50= 50 mg/l.

The Potassium amyl xanthate (CAS No. 2720-73-2), the subject of this dossier) is expected to exhibit very similar toxicity to Potassium ethyl xanthate (CAS No. 140-89-6), which is also xanthate compound.. Comparable metabolism would occur.