Oxalonitrile

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Ethanedinitrile, hydrogen cyanide (HCN), potassium cyanide and sodium cyanide can be considered as a chemical category, along with and acetone cyanohydrin (ACH, also known as 2-hydroxy-2-methylpropanenitrile), based on structural similarity, common breakdown/metabolic products in physical and biological systems, and similar physico-chemical properties. Particular attention is paid to the dissociation constant of HCN. Ethanedinitrile breaks down in aqueous solution into cyanide ion (CN-) and cyanate ion (OCN-) (Cotton and Wilkinson 1980). Ethanedinitrile due to its low log Kow (0.07) and relatively high solubility in water (2.34 g/L) needs to get dissolved in aqueous solutions in lungs to enter the body. The rate of hydrolysis of ethanedinitrile is very fast (Ajwa 2015). Also, in the vast majority of environmental and physiologic conditions, the cyanide salts will dissolve in water to form hydrogen cyanide. The physico-chemical hazards and toxicity therefore result from the activity of HCN. An ECETOC Task Force, in the 2007 ECETOC Joint Assessment of Commodity Chemicals (JACC) Report No. 53, “Cyanides of Hydrogen, Sodium and Potassium, and Acetone Cyanohydrin (CAS No. 74-90-8, 143-33-9, 151-50-8 and 75-86-5)” supports the development of the chemical category inclusive hydrogen cyanide, sodium and potassium cyanides. Hydrogen cyanide (Index No.006-006-00-X) and salts of hydrogen cyanides (Index No.006-007-00-5) are both listed in Annex VI, Table 3.1 of Regulation (EC) No. 1272/2008, entry 006-007-00-5, and are restricted in comparable ways taking into account physical characteristics. Thus, the assignment of ethanedinitrile to a chemical category does not result in a less protective regulatory status.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

23 +/- °C

Details on test conditions:

Initial algae culture concentration: 10,000 cells in 1 ml
Exposure: 72 hours
Lighting: continual, min 6,000 lux, max 10,000 lux.
Volume of tested solution: 50 ml
No aeration
Algae culture mixed by shaking, swing 40 mm, frequency degree 4

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

EbC50

Effect conc.:

0.04 mg/L

Key result

Duration:

72 h

Dose descriptor:

EC50

Remarks:

ErC50

Effect conc.:

0.12 mg/L

Measured and calculated data Algal growth inhibition: Table: Preliminary test dilution ml.L^-1 conc. mg.L^-1 Algae culture concentration number of cells in 1 ml Ir(%) IA(%) in 24 hours in 48 hours in 72 hours 170 2.55 6,250 0 0 100 100 80 1.20 6,250 6,250 6,250 100 100 50 0.75 18,750 6,250 6,250 100 99.8 40 0.60 12,500 6,250 12,500 95.9 100 20 0.30 12,500 12,500 25,000 82.0 99.0 10 0.15 25,000 56,250  100,000 55.2 91.6 3 0.045 37,500  131,250 1, 043,750 9.9 47.3 1 0.015 43,750  206,250 1,318,750 5.2 30.0 Control 0 37,500  375,000 1,750,000 - -   Table: First test                                                                          dilution ml.L^-1 conc. mg.L^-1 pH 0 hours pH 72 hours Algae culture concentration number of cells in 1 ml Ir(%) IA(%) in 24 hours in 48 hours in 72 hours 20 0.30 7.81 7.94 8,333 31,250 41,667 72.3 97.5 10 0.15 7.80 7.95 12,500 50,000 75,000 61.3 94.7 8 0.12 7.80 8.02 20,833 89,583 122,917 51.4 89.5 6 0.09 7.80 8.19 29,167 104,167 266,667 37.0 82.8 4 0.06 7.80 8.63 37,500 189,583 737,500 17.3 59.3 2 0.03 7.79 8.70 52,083 220,833 839,583 14.5 52.4 1 0.015 7.78 8.97 58,333 462,500 1,664,583 1.7 5.3 Control 0 7.78 8.87 70,833 456,250 1,802,083 - -   Table: Second test                                                                                    dilution ml.L^-1 conc. mg.L^-1 pH 0 hours pH 72 hours Algae culture concentration number of cells in 1 ml Ir(%) IA(%) in 24 hours in 48 hours in 72 hours 20 0.30 7.95 7.76 14,583 22,917 45,833 70.3 97.1 10 0.15 7.93 7.79 25,000 31,250 60,417 65.1 95.0 8 0.12 7.93 7.84 27,083 41,667 97,917 55.8 92.4 6 0.09 7.93 7.94 31,250 81,250 181,250 43.6 85.4 4 0.06 7.92 8.25 33,333 129,167 343,750 31.4 74.7 2 0.03 7.91 9.07 37,500 177,083 756,250 16.3 53.6 1 0.015 7.90 9.20 43,750 231,250 1,333,333 5.2 25.0 Control 0 7.88 9.25 58,333 329,167 1,720,833 - -

Conclusions:

The results of Algal Growth Inhibition Test with exposure of Scenedesmus (Desmodesmus) subspicatus to hydrogen cyanide are:
EbC50 (0-72h) = 0.04 mg.L-1
ErC50 (0-72h) = 0.12 mg.L-1

Executive summary:

 

The tested substance, hydrogen cyanide, liquid, stabilized, was subject to a test of algal growth inhibition. Considering the expected substance toxicity detected in a preliminary test, a complete test was carried out two times.

 

Test conditions:

• 
  

  Temperature: 23 ± 2°C

  
  


• 
  

  Lighting: continual, min 6,000 lux, max 10,000 lux.

  
  


• 
  

  Exposure: 72 hours

  
  


• 
  

  Volume of tested solution: 50 ml

  
  


• 
  

  Initial algae culture concentration: 10,000 cells in 1 ml

  
  


• 
  

  No aeration

  
  


• 
  

  Algae culture mixed by shaking, swing 40 mm, frequency degree 4

  
  

Preliminary test:

• 
  

  Basic solution of the tested substance: 15 mg.L^-1

  
  


• 
  

  Inoculation algae culture volume: 0.61 ml in 50 ml mixture

  
  


• 
  

  Lighting during test: 6,300 Lux

  
  


• 
  

  Temperature during test: 22.0 – 22.5°C

  
  

Based on the preliminary test results, a complete test was started.

Complete test was performed in 7 concentrations of the tested substance that were determined on the basis of preliminary test results and in control solution without the tested substance. The concentrations were tested parallelly in three rows. The whole test was repeated two times. Test procedure as such was identical as in the case of preliminary test.

 

Test 1:

• 
  

  Basic solution of tested substance: 15 mg.L^-1

  
  


• 
  

  Inoculation algae culture volume: 0.42 ml in 50 ml solution

  
  


• 
  

  Lighting during test: 6,200 – 6,300 Lux

  
  


• 
  

  Temperature during test: 22.5°C

  
  

Test 2:

• 
  

  Basic solution of tested substance: 15 mg.L^-1

  
  


• 
  

  Inoculation algae culture volume: 0.78 ml in 50 ml solution

  
  


• 
  

  Lighting during test: 6,300 – 6,400 Lux

  
  


• 
  

  Temperature during test: 22.0 – 22.5°C

  
  

 

Determination of concentration of the tested substance

At the beginning and at the end of the test, a determination of concentration of the tested substance was carried out by volumetric method.

Solutions in flasks with the highest concentration of the tested substance were analysed. Solutions with the lowest content of the tested substance could not be analysed as their concentrations were below determination limit of the used analytical method, which is 0.1 mg.L^-1in direct determination; therefore, such concentration that can still be safely determined was opted for. All determinations were carried out after the algae were filtered away. Filtration was performed using an inert membrane filter with 0.2 µm porosity.

 

Measured and calculated data

 

Algal growth inhibition:

 

Table 8.2.6.1 – 3.Preliminary test

dilution ml.L^-1	conc. mg.L^-1	Algae culture concentration number of cells in 1 ml			Ir(%)	IA(%)
		in 24 hours	in 48 hours	in 72 hours
170	2.55	6,250	0	0	100	100
80	1.20	6,250	6,250	6,250	100	100
50	0.75	18,750	6,250	6,250	100	99.8
40	0.60	12,500	6,250	12,500	95.9	100

 

20	0.30	12,500	12,500	25,000	82.0	99.0
10	0.15	25,000	56,250	100,000	55.2	91.6
3	0.045	37,500	131,250	1, 043,750	9.9	47.3
1	0.015	43,750	206,250	1,318,750	5.2	30.0
Control	0	37,500	375,000	1,750,000	-	-

 

 

Table 8.2.6.1 – 4.First test                                                                       

dilution ml.L^-1	conc. mg.L^-1	pH 0 hours	pH 72 hours	Algae culture concentration number of cells in 1 ml			Ir(%)	IA(%)
				in 24 hours	in 48 hours	in 72 hours
20	0.30	7.81	7.94	8,333	31,250	41,667	72.3	97.5
10	0.15	7.80	7.95	12,500	50,000	75,000	61.3	94.7
8	0.12	7.80	8.02	20,833	89,583	122,917	51.4	89.5
6	0.09	7.80	8.19	29,167	104,167	266,667	37.0	82.8
4	0.06	7.80	8.63	37,500	189,583	737,500	17.3	59.3
2	0.03	7.79	8.70	52,083	220,833	839,583	14.5	52.4
1	0.015	7.78	8.97	58,333	462,500	1,664,583	1.7	5.3
Control	0	7.78	8.87	70,833	456,250	1,802,083	-	-

 

Table 8.2.6.1 – 5.Second test                                                                                

dilution ml.L^-1	conc. mg.L^-1	pH 0 hours	pH 72 hours	Algae culture concentration number of cells in 1 ml			Ir(%)	IA(%)
				in 24 hours	in 48 hours	in 72 hours
20	0.30	7.95	7.76	14,583	22,917	45,833	70.3	97.1
10	0.15	7.93	7.79	25,000	31,250	60,417	65.1	95.0
8	0.12	7.93	7.84	27,083	41,667	97,917	55.8	92.4
6	0.09	7.93	7.94	31,250	81,250	181,250	43.6	85.4
4	0.06	7.92	8.25	33,333	129,167	343,750	31.4	74.7
2	0.03	7.91	9.07	37,500	177,083	756,250	16.3	53.6
1	0.015	7.90	9.20	43,750	231,250	1,333,333	5.2	25.0
Control	0	7.88	9.25	58,333	329,167	1,720,833	-	-

 

CA 8.1.1.1 Effects on growth of an additional algal species

The substance will be dispatched in the air and will get quickly diluted due to its high volatility. The substance will stay in the air based on its physical and chemical properties and will not transfer to

other environmental compartments such as soil and water as confirmed by models in the environmental fate part of dossier, CA 7.3.2.Literature data suggest range from 5.3 to 30,000 ug CN/L for LOEC, EC50 and

NOEC data towards 8 algal or cyanobacterial speciesGensemeret al.(2005).

 

CA 8.1.2 Effects on aquatic macrophytes

The substance will be dispatched in the air and will get quickly diluted due to its high volatility. The substance will stay in the air based on its physical and chemical properties and will not transfer to other environmental compartments such as soil and water as confirmed by models in the environmental fate part of dossier, CA 7.3.2.

Instead of data on ethanedinitrile, data on hydrogen cyanide are presented which are more appropriate than data on the active compound according to OECD23 (Guidance Document On Aquatic Toxicity Testing Of Difficult Substances And Mixtures) due to the rapid hydrolysis in water.

 

The results of Algal Growth Inhibition Test with exposure of Scenedesmus (Desmodesmus) subspicatusto hydrogen cyanide are:

E_bC₅₀(0-72h) = 0.04 mg.L^-1

E_rC₅₀(0-72h) = 0.12 mg.L^-1

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Justification for type of information:

Ethanedinitrile, hydrogen cyanide (HCN), potassium cyanide and sodium cyanide can be considered as a chemical category, along with and acetone cyanohydrin (ACH, also known as 2-hydroxy-2-methylpropanenitrile), based on structural similarity, common breakdown/metabolic products in physical and biological systems, and similar physico-chemical properties. Particular attention is paid to the dissociation constant of HCN. Ethanedinitrile breaks down in aqueous solution into cyanide ion (CN-) and cyanate ion (OCN-) (Cotton and Wilkinson 1980). Ethanedinitrile due to its low log Kow (0.07) and relatively high solubility in water (2.34 g/L) needs to get dissolved in aqueous solutions in lungs to enter the body. The rate of hydrolysis of ethanedinitrile is very fast (Ajwa 2015). Also, in the vast majority of environmental and physiologic conditions, the cyanide salts will dissolve in water to form hydrogen cyanide. The physico-chemical hazards and toxicity therefore result from the activity of HCN. An ECETOC Task Force, in the 2007 ECETOC Joint Assessment of Commodity Chemicals (JACC) Report No. 53, “Cyanides of Hydrogen, Sodium and Potassium, and Acetone Cyanohydrin (CAS No. 74-90-8, 143-33-9, 151-50-8 and 75-86-5)” supports the development of the chemical category inclusive hydrogen cyanide, sodium and potassium cyanides. Hydrogen cyanide (Index No.006-006-00-X) and salts of hydrogen cyanides (Index No.006-007-00-5) are both listed in Annex VI, Table 3.1 of Regulation (EC) No. 1272/2008, entry 006-007-00-5, and are restricted in comparable ways taking into account physical characteristics. Thus, the assignment of ethanedinitrile to a chemical category does not result in a less protective regulatory status.

Qualifier:

no guideline followed

Principles of method if other than guideline:

test procedure in accordance with generally accepted scientific standards

GLP compliance:

no

Key result

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

>= 5.3 - <= 30 000 µg/L

Conclusions:

The substance will be dispatched in the air and will get quickly diluted due to its high volatility. The substance will stay in the air based on its physical and chemical properties and will not transfer to other environmental compartments such as soil and water as confirmed by models in the environmental fate part of dossier (10.3 Fate and behaviour in air).
Literature data suggest range from 5.3 to 30,000 ug CN/L for LOEC, EC50 and NOEC data towards 8 algal or cyanobacterial species Gensemer et al. (2005).

Executive summary:

The substance will be dispatched in the air and will get quickly diluted due to its high volatility. The substance will stay in the air based on its physical and chemical properties and will not transfer to other environmental compartments such as soil and water as confirmed by models in the environmental fate part of dossier (10.3 Fate and behaviour in air). Literature data suggest range from 5.3 to 30,000 ug CN/L for LOEC, EC50 and NOEC data towards 8 algal or cyanobacterial species.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Remarks:

Effects on growth rate of green algae

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

22.9 °C - 23.2 °C

pH:

7.0 - 7.96

Details on test conditions:

Volume of tested mixture: 50ml
Illumination: 24 hours per day
Light intensity: 7346 lx
Intensity of stirring with flask: 4 per day

Key result

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

1.79 mg/L

Details on results:

In order to reach higher specification of IC50, another basic test was performed in different span of concentrations.

Table: Basic test 1 –Desmodesmus subspicatus Concentration [mg/L] K 0.5 1 2 4 7 10 Inhibition [%] 0 3.6 54.1 93.1 89.8 100 >100

Table. Basic test 2 –Desmodesmus subspicatus Concentration [mg/L] K 0.4 0.6 0.8 1.0 2.0 3.0 Inhibition [%] 0 8.5 8.2 14.5 14.9 36.8 96.2

Conclusions:

The 72-hour IC50 of ethanedinitrile towards Desmodesmus subspicatus was estimated to be 1.79mg/L.
The substance will be dispatched in the air and will get quickly diluted due to its high volatility. The substance will stay in the air based on its physical and chemical properties and will not transfer to other environmental compartments such as soil and water as confirmed by models.

Executive summary:

The 72-hour IC₅₀ of ethanedinitrile towards Desmodesmus subspicatus was estimated to be 1.79mg/L.

Exposure of aquatic organisms is not expected. The substance will be dispatched in the air and will get quickly diluted due to its high volatility. The substance will stay in the air based on its physical and chemical properties and will not transfer to other environmental compartments such as soil and water as confirmed by models.

Description of key information

Ethanedinitrile: The substance will stay in the air based on its physical and chemical properties and will not transfer to other environmental compartments such as soil and water as confirmed by models in the environmental fate part of dossier (10.3 Fate and behaviour in air). Literature data suggest range from 5.3 to 30,000 ug CN/L for LOEC, EC50 and NOEC data towards 8 algal or cyanobacterial species Gensemer et al. (2005).

 

Hydrogencyanide: The results of Algal Growth Inhibition Test with exposure of Scenedesmus (Desmodesmus) subspicatus to hydrogen cyanide are: EbC50 (0-72h) = 0.04 mg.L-1 ErC50 (0-72h) = 0.12 mg.L-1

Key value for chemical safety assessment

EC50 for freshwater algae:

1.79 mg/L