Oxalonitrile

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

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.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Details on sampling:

For each test one control test (with dilution water) was carried out. Base (“primary”) solution of test substance: 15 mg.L-1 of distilled water. Test media of the required concentration for both the range finding test and the definitive test were prepared from the base solution by serial dilution with dilution water. 7 and 8 concentrations were studied in the range-finding test and the definitive test, respectively. For the definitive test, 20 animals at each test concentration divided into two batches of 10 animals each were studied.

Details on test solutions:

Basic solution was prepared in distilled water with concentration 15 mg.l-1. Concentrations of solution used in the test were obtained by diluting the basic solution with dilution water.

Test organisms (species):

Daphnia magna

Details on test organisms:

10 organisms for each concentration and check in preliminary test, 20 organisms for concentration and check in complete test.

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Test temperature:

20+/-2 °C

pH:

7.82

Dissolved oxygen:

No aeration

Details on test conditions:

Lightenoing: Daylight
Solution volume: 50 ml (10 individuals)
pH and oxygen content measurement: at the beginning and at the end of complete (limit) test for
each test concentration and trial.

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

1.18 mg/L

95% CI:

>= 0.88 - <= 1.47

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.03 mg/L

95% CI:

>= 0.9 - <= 1.16

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

1.27 mg/L

95% CI:

>= 0.92 - <= 1.62

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1.11 mg/L

95% CI:

>= 0.95 - <= 1.26

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

1. Range-finding test concentrations in mg.L^-1: 2.1, 1.8, 1.5, 1.2, 0.9, 0.6, 0.3 mg.L^-1 2. Definitive test concentrations in mg.L^-1: 1.8, 1.65, 1.50, 1.35, 1.20, 1.05, 0.90, 0.75 mg.L^-1   Table8.2.4.1. – 4. (1^strun): Effect data   EC50 [mg.L^-1] 95 % c.L. Approximation function 24 hours 1.18 0.88 – 1.47 log linear 48 hours 1.03 0.90 – 1.16 log linear   Table 8.2.4.1. – 5. (2^ndrun): Effect data   EC50 [mg.L^-1] 95 % c.L. Approximation function 24 hours 1.27 0.92 – 1.62 log linear 48 hours 1.11 0.95 – 1.26 log linear

The 48-hour EC₅₀of hydrogen cyanide to Daphnia magna was estimated to be 1.07 mg/L.

Conclusions:

The 48-hour EC50 of hydrogen cyanide toDaphnia magna was estimated to be 1.07 mg/L.

Executive summary:

Test was performed in GLP compliant laboratory following GLP conditions, with GLP trained staff according to OECD guideline 202.

Stabilized hydrogen cyanide liquid was tested for acute toxicity to water fleas (Daphnia magna). For a range-finding test the total of 140 young daphnid (less than 24 hours old) were exposed to seven concentrations and control. For a definitive test the total of 320 young daphnid (less than 24 hours old) were exposed to 8 concentrations, controls and replicates. The duration of exposure was 24 and 48 hours under static conditions. Test concentrations were verified by argentometric titration.

1. Range-finding test concentrations in mg.L^-1: 2.1, 1.8, 1.5, 1.2, 0.9, 0.6, 0.3 mg.L^-1 2. Definitive test concentrations in mg.L^-1: 1.8, 1.65, 1.50, 1.35, 1.20, 1.05, 0.90, 0.75 mg.L^-1 Table8.2.4.1. – 4. (1^strun): Effect data   EC50 [mg.L^-1] 95 % c.L. Approximation function 24 hours 1.18 0.88 – 1.47 log linear 48 hours 1.03 0.90 – 1.16 log linear   Table 8.2.4.1. – 5. (2^ndrun): Effect data   EC50 [mg.L^-1] 95 % c.L. Approximation function 24 hours 1.27 0.92 – 1.62 log linear 48 hours 1.11 0.95 – 1.26 log linear

The 48-hour EC₅₀of hydrogen cyanide to Daphnia magna was estimated to be 1.07 mg/L.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

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 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Test conducted with considerations of "The Chironomid Acute Toxicity Test: development of a new test system”, Weijte, L., et al. (2009) and OECD Draft Test Guideline for an Acute Chironomid Test (version of 11.03.2011, ENV/JM/TG (2011)16).

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

At test start samples of the control and all double concentrated application solutions were taken just before distributing it to the replicates and measured. The double concentrated solutions were applied for measurement to ensure adequate results also in the lowest treatment to demonstrate accurate concentrations at start and renewal. At media renewal, samples of the final test solutions were measured to show the real concentration right after introduction and mixing. Aged media were sampled out of each replicate and pooled per concentration for measurement. Samples were analyzed immediately after sampling.

Test organisms (species):

other aquatic arthropod: Chironomus riparius

Details on test organisms:

First instar specimens originally obtained from Bayer Crop Science AG, and bred in the Faunhofer IME laboratory for many generations. Chironomids showed no signs of stress (high mortality or discolouration), maintained under conditions similar to the test and fed daily with TetraMin® Hauptfutter. Seven days before adding the test organisms to the test vessels, egg masses (<24 h) were taken from the cultures and placed in small aerated vessels (Petri dishes) with test water at about 20 oC. Larvae were fed until start of exposure. First instar larvae (3 days post-hatching) were used in the test. Only apparently healthy specimens were used in the study. Test specimens were removed by wide bore pipette (to avoid damage) and isolated in fresh dilution water for at least one hour prior to being exposed to the appropriate test or control media.

Test type:

semi-static

Water media type:

freshwater

Total exposure duration:

48 h

Hardness:

1.1 mmol/L total hardness in dilution water.

Test temperature:

Temperature ranged from 20 degrees C to 20.5 degrees C during the conduct of the test.

pH:

The pH ranged from 8.4 to 8.6 during the conduct of the test.

Dissolved oxygen:

Dissolved oxygen ranged from 95% saturation to 102% saturation (TWA) during the conduct of the test.

Nominal and measured concentrations:

Nominal concentrations of free cyanide: 5.31 ug/L; 13.3 ug/L; 33.2 ug/L; 82.8 ug/L; 208 ug/L.
Measured concentrations of free cyanide (TWA): 3.70 ug/L; 6.95 ug/L; 12.9 ug/L; 22.5 ug/L; and 47.0 ug/L.

Details on test conditions:

Incubation took place in a fume hood. The beakers were covered with glass panes and subjected to a light/dark cycle of 16/8 hours. The test temperature during the 20 +/- 2 degrees C and was constant within +/- 1 degree C during the test.

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

32.5 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

labile/free

Remarks:

free cyanide

Basis for effect:

mobility

Remarks on result:

other: 95% UCL: 21.4 - 75.6 ug/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

12.4 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

labile/free

Remarks:

free cyanide

Basis for effect:

mobility

Remarks on result:

other: 95% UCL: 6.4 - 23.0 ug/L

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

6.9 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

labile/free

Remarks:

free cyanide

Basis for effect:

mobility

Validity criteria fulfilled:

yes

Conclusions:

Exposure to sodium cyanide resulted in a NOEC of 6.9 ug free CN-/L (TWA) for acute immobilization of larvae of Chironomus riparius under the chosen test conditions. The 24-h EC50 is 32.5 ug free CN-/L (TWA), the 48 h EC50 is 12.4 ug free CN-/L (TWA).

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Remarks:

Daphnia magna

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 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna Straus, family - Crustacea

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Test temperature:

20.8 - 22.0

pH:

6.59 - 8.16

Dissolved oxygen:

without aeration

Nominal and measured concentrations:

5+1 dilution - water control series

Details on test conditions:

day light , with feeding

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

3.33 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Table 8.2.4.1. – 1. - Preliminary test – Daphnia magna Concentration [mg/L]   C           1            2            3            5            10 Immobilization [%]         0           5            15          10          50          90   Concentrations for basic test 1 were selected according to the results of preliminary test. These concentrations and percentage of immobilization are in Table8.2.4.1. – 2.   Table 8.2.4.1. – 2. - Basic test 1 – Daphnia magna Concentration [mg/L]   C           0.5         1            2            4            5 Immobilization [%]         0           0            0            35          70          100   48-hour EC50= 2.97 mg/L   In order to reach higher specification of EC50, another basic test was performed in different span of concentrations.   Concentration series of basic test 2 were selected according to the results of basic test 1. These concentrations and percentage of inhibition are in Table8.2.4.1. – 3.   Table 8.2.4.1. – 3. - Basic test 2 – Daphnia magna Concentration [mg/L]   C           1            2            3            4            5 Immobilization [%]         0           0            10          35          60          90   48-hour EC50= 3.33 mg/L   The 48-hour EC50of ethanedinitrile towards Daphnia magnawas estimated to be 3.33 mg/l.

Conclusions:

The 48-hour EC50 of ethanedinitrile towards Daphnia magna was estimated to be 3.33 mg/l.

Executive summary:

Test was performed in GLP compliant laboratory following GLP conditions, with GLP trained staff according to OECD guideline 202. Young daphnids, aged less than 24 hours at the beginning of the test, are exposed to the test substance at a range of concentrations for a period of 48 hours. Immobilization is recorded at 24 hours and 48 hours and compared with control values. The results are analysed in order to calculate the EC50 at 48 hours. The 48-hour EC50 of ethanedinitrile towards Daphnia magna was estimated to be 3.33 mg/l.

Description of key information

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. More than 20 aquatic invertebrate species were tested towards cyanides in Gensemer (2005). The LC50s were in the range of 78 – 50,000 ug CN / L in 48 to 96-hour long exposures.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

3.33 mg/L