Oxalonitrile

Phototransformation in air

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in air

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Conclusions:

Most of the ethanedinitrile naturally present in the environment is located in the atmosphere and only negligible amounts are transported to soil and water.
Cyanogen is reactive and does not persist in the environment unchanged (EPA 1978c, ATSDR 2006). One of possible degradation pathways is hydrolysis in the atmosphere. Cyanogen reacts with water to yield hydrogen cyanide and cyanic acid (HOCN) (Yngard 2008, EPA 1979, ATSDR 2006).
Cyanogen also reacts with hydroxyl radicals in the gas phase (Atkinson 1989) however, based on the range constant and assuming average concentration of hydroxyl radicals, the residence time for the reaction of cyanogen with hydroxyl radical in the atmosphere is about 25 years.

Executive summary:

Route and rate of degradation in air

Most of the ethanedinitrile naturally present in the environment is located in the atmosphere and only negligible amounts are transported to soil and water. Cyanogen is reactive and does not persist in the environment unchanged (EPA 1978c, ATSDR 2006). One of possible degradation pathways is hydrolysis in the atmosphere. Cyanogen reacts with water to yield hydrogen cyanide and cyanic acid (HOCN) (Yngard 2008, EPA 1979, ATSDR 2006). Cyanogen also reacts with hydroxyl radicals in the gas phase (Atkinson 1989) however, based on the range constant and assuming average concentration of hydroxyl radicals, the residence time for the reaction of cyanogen with hydroxyl radical in the atmosphere is about 25 years.

Reference 2

Endpoint:

phototransformation in air

Type of information:

other: Model

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

Principles of method if other than guideline:

OECD Pov (overall persistence) and LRTP (long range transport potential) screening tool was used to study fate of ethanedinitrile. According the scientific article about this model (Wegmann at al. 2009) and manual from OECD webpage (OECD 2009) this model is designed to support decision making for chemical management and includes features that are recommended by the Organization for Economic Cooperation and Development (OECD) expert group on multimedia modelling. The Tool software has been designed to implement the recommendations of the OECD expert group on multimedia modelling, and to facilitate screening of individual chemicals and large sets of substances for POP-like POV and LRTP properties.
POV (overall persistence), CTD (characteristic travel distance, km) and TE (transport efficiency, %) values obtained for the three scenarios of emissions to soil, water and air are listed.
The three pie charts (attached excel file 09_EDN_LZD_Model_LRTP_EDN results_2016) show the chemical’s fractions that are contained in soil, water and air in the three emission scenarios. In addition to these primary model results, the page displays a table with properties of the model compartments (bulk compartment properties and sub-compartment properties) and with all mass fluxes calculated by the model (degrading reactions, physical removal, and inter-compartment exchange).
With these numbers, the users can identify processes that dominate the observed fate of a particular chemical.

Specific details on test material used for the study:

Parameters of ethanedinitrile entered into the model:
MW=52.04
Log Kaw = -1.851 (value from Chemspider, calculated)
Log Kow = 0.07 (value from Chemspider, calculated)
Half-life in air (hours) – 3624 h (experimental data, photolysis in air in the dark)
Half-life in water (hours) – 0.84 h (experimental data, hydrolysis, pH = 7)
Half-life in soil (hours) – 1000 h (default value-worst case, data not available)

Conclusions:

Time of persistence, transport potential (CTD) – km and distribution between compartments for various emission scenario (emission to air, water or soil) and other parameters are described in this model. For ethanedinitrile, overall persistence time (Pov) is 98 days (based on persistence time in air) and travel distance is 32 868 km.
When there is emission of ethanedinitrile to air only, most of the compound (99.96%) remains in air and only 0.03% is transported to water and only 0.01% is transported to soil.
Thus, ethanedinitrile is transported to long distances, however, remains mostly in air.

Executive summary:

Modelling of transport of ethanedinitrile after releasing of ethanedinitrile to air after timber fumigation – OECD LRTP model Introduction to OECD LRTP model OECD Pov (overall persistence) and LRTP (long range transport potential) screening tool was used to study fate of ethanedinitrile. According the scientific article about this model (Wegmann at al. 2009) and manual from OECD webpage (OECD 2009) this model is designed to support decision making for chemical management and includes features that are recommended by the Organization for Economic Cooperation and Development (OECD) expert group on multimedia modelling. The Tool software has been designed to implement the recommendations of the OECD expert group on multimedia modelling, and to facilitate screening of individual chemicals and large sets of substances for POP-like POV and LRTP properties. POV (overall persistence), CTD (characteristic travel distance, km) and TE (transport efficiency, %) values obtained for the three scenarios of emissions to soil, water and air are listed. The three pie chartsshow the chemical’s fractions that are contained in soil, water and air in the three emission scenarios. In addition to these primary model results, the page displays a table with properties of the model compartments (bulk compartment properties and sub-compartment properties) and with all mass fluxes calculated by the model (degrading reactions, physical removal, and inter-compartment exchange). With these numbers, the users can identify processes that dominate the observed fate of a particular chemical.   I.       Methods   Parameters of ethanedinitrile entered into the model: MW=52.04 Log Kaw = -1.851 (value from Chemspider, calculated) Log Kow = 0.07 (value from Chemspider, calculated) Half-life in air (hours) – 3624 h (experimental data, photolysis in air in the dark) Half-life in water (hours) – 0.84 h (experimental data, hydrolysis, pH = 7) Half-life in soil (hours) – 1000 h (default value-worst case, data not available)   II.     Conclusion Time of persistence, transport potential (CTD) – km and distribution between compartments for various emission scenario (emission to air, water or soil) and other parameters are described in this model. For ethanedinitrile, overall persistence time (Pov) is 98 days (based on persistence time in air) and travel distance is 32 868 km. When there is emission of ethanedinitrile to air only, most of the compound (99.96%) remains in air and only 0.03% is transported to water and only 0.01% is transported to soil.

Thus, ethanedinitrile is transported to long distances, however, remains mostly in air.

Reference 3

Endpoint:

phototransformation in air

Remarks:

in environment in general

Type of information:

other: model

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

Principles of method if other than guideline:

This overview summarizes the results of environmental fate of ethanedinitrile by model EQC (EQuilibrium Criterion). This model uses chemical-physical properties to quantify a chemical‘s behavior in an evaluative environment. It is useful for establishing the general features of a new or existing chemical‘s behavior, i.e. the media into which the chemical will tend to partition, the primary loss mechanism and its tendency for intermedia transport (EQC model 2003).
There are three degrees of complexity treated in the EQC, for our purposes we have used Level III, which is a non-equilibrium, steady state assessment of chemical fate in the environment (EQC model 2003). This level (III) was evaluated as the most realistic for characterization of the environmental fate of the compound (Hughes et al. 2012).


Methods

Input parameters
Input parameters (chemical-physical properties, half-lives of ethanedinitrile in water, air, soil and sediment) are described in. Data for chemical-physical properties are based mostly on literature data and half-lives are values from experimental studies – data for most probable scenario in the environment (neutral pH, temperature ±23°C etc.) are set for this model. For half-life in sediment and soil was used default value 1000 h, because there are no reliable data from the literature or from our experimental studies. However, the real half-life in sediment or soil is probably lower. As input emissions we used 3000t/year, which is the highest capacity of our factory.

In picture below (Overall remarks, attachments: Illustration (picture/graf)), you can see diagram with partitioning of ethanedinitrile in air, soil, water and sediment, when emission of 3000 t C2N2/year is produced. In this diagram you can see, that most of ethanedinitrile (almost 100%) remains in air and only minor amount is transported to water, soil or sediment. The amount distributed into soil is 0.0048% and for water it is 0.000125%. According to this model, respective concentration for amount 3000 t/year will be 0.0000007 ng/g solids and concentration in water will be 0.0002 ng/L. These concentrations are negligible compared to toxic concentrations of ethanedinitrile for fish or algae (toxic concentrations are more than 1 mg/L).

Conclusions:

As reported in this model, most of ethanedinitrile which is emitted to air (as it is in our case) remains in air and only minor amounts are transported to water, soil or sediment. Concentrations in environmental compartments are very low compared to concentrations that present risk for nature or humans.

Executive summary:

Modelling of transport of ethanedinitrile after releasing of ethanedinitrile to air after timber fumigation – EQC model Introduction to EQC model This overview summarizes the results of environmental fate of ethanedinitrile by model EQC (EQuilibrium Criterion). This model uses chemical-physical properties to quantify a chemical‘s behavior in an evaluative environment. It is useful for establishing the general features of a new or existing chemical‘s behavior, i.e. the media into which the chemical will tend to partition, the primary loss mechanism and its tendency for intermedia transport (EQC model 2003). There are three degrees of complexity treated in the EQC, for our purposes we have used Level III, which is a non-equilibrium, steady state assessment of chemical fate in the environment (EQC model 2003). This level (III) was evaluated as the most realistic for characterization of the environmental fate of the compound (Hughes et al. 2012).   I.       Methods   Input parameters Input parameters (chemical-physical properties, half-lives of ethanedinitrile in water, air, soil and sediment) are described in. Data for chemical-physical properties are based mostly on literature data and half-lives are values from experimental studies – data for most probable scenario in the environment (neutral pH, temperature ±23°C etc.) are set for this model. For half-life in sediment and soil was used default value 1000 h, because there are no reliable data from the literature or from our experimental studies. However, the real half-life in sediment or soil is probably lower. As input emissions we used 3000t/year, which is the highest capacity of our factory.   II.     Results   In Fig.1, you can see diagram with partitioning of ethanedinitrile in air, soil, water and sediment, when emission of 3000 t/year ethanedinitrile is produced. In this diagram you can see, that most of ethanedinitrile (almost 100%) remains in air and only minor amount is transported to water, soil or sediment. The amount distributed into soil is 0.0048% and for water it is 0.000125%. According to this model, respective concentration for amount 3000 t/year will be 0.0000007 ng/g solids and concentration in water will be 0.0002 ng/L. These concentrations are negligible compared to toxic concentrations of ethanedinitrile for fish or algae (toxic concentrations are more than 1 mg/L).   III.   Conclusion

As reported in this model, most of ethanedinitrile which is emitted to air (as it is in our case) remains in air and only minor amounts are transported to water, soil or sediment. Concentrations in environmental compartments are very low compared to concentrations that present risk for nature or humans.

Reference 4

Endpoint:

phototransformation in air

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Conclusions:

The reaction of cyanogen with OH-radical has been also calculated by atmospheric oxidation program (AOP), a model included in the Estimation Program Interface (EPI), U.S. Environmental Protection Agency, Washington, DC.
According to this model, ethanedinitrile does not react with hydroxyl radicals in the atmosphere. These data are in agreement with mentioned literature data of experimental studies, where the reaction of cyanogen with hydroxyl radical is very slow, with residence time for reaction with hydroxyl radical about 25 years (Atkinson 1989). For details of AOP model see Report 1 AOP.

Executive summary:

The reaction of cyanogen with OH-radical has been also calculated by atmospheric oxidation program (AOP), a model included in the Estimation Program Interface (EPI), U.S. Environmental Protection Agency, Washington, DC. According to this model, ethanedinitrile does not react with hydroxyl radicals in the atmosphere. These data are in agreement with mentioned literature data of experimental studies, where the reaction of cyanogen with hydroxyl radical is very slow, with residence time for reaction with hydroxyl radical about 25 years (Atkinson 1989). For details of AOP model see Report 1 AOP.

Reference 5

Endpoint:

phototransformation in air

Type of information:

experimental study

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

Principles of method if other than guideline:

Photolysis in air was evaluated following procedures published for soil fumigants (referenced in 09_EDN_AJWA_photolysis_2015: Moilanen et al., 1978) with these exceptions:
1) The incubation temperature stated in the protocol is 23 ± 2oC for both dark and light incubation. In this study, the incubation temperature was 21.5 ± 2.5°C for the dark incubator and 25 ± 2°C.
Impact on the study: None. Temperature in the study range has no significant effect of cyanogen degradation.
2) The degradation products were not identified due to the slow degradation process.
Impact on the study: None. The concentrations of the degradation products were very small and accurate measurements were not possible. Degradation products were identified in a separate study.

GLP compliance:

yes

Light source:

other: UV light

Details on test conditions:

The experiments were performed to determine the rate of cyanogen decomposition in air inside a closed 160-mL bottle. In the dark at 21.5 ± 2.5°C, the half-life of cyanogen was 150 days, at 25 ± 2°C under continuous UV light (1500-2500 µw/cm2), the half-life was reduced to 98 days. Photolysis in air was evaluated following procedures published for soil fumigants (referenced in 09_EDN_AJWA_photolysis_2015: Moilanen et al., 1978) with these exceptions:
1) The incubation temperature stated in the protocol is 23 ± 2oC for both dark and light incubation. In this study, the incubation temperature was 21.5 ± 2.5°C for the dark incubator and 25 ± 2°C.
Impact on the study: None. Temperature in the study range has no significant effect of cyanogen degradation.
2) The degradation products were not identified due to the slow degradation process.
Impact on the study: None. The concentrations of the degradation products were very small and accurate measurements were not possible. Degradation products were identified in a separate study.

Conclusions:

Cyanogen is stable in air; the half-life is 98 days at 25±2°C under UV light and 151 days at 21.5±2.5°C in the dark. This study used continuous light over 24-hour period. However, direct sunlight has higher intensity (measured UVA and UVB intensity of 9000 µW/cm2) and cyanogen may degrade at a faster rate under direct sunlight, especially if the air has high relative humidity. Hydrolysis in water (under light and in the dark) was conducted in a different study (AAL-2015-12).

Executive summary:

Chemicals can escape to the air or enter surface water by such routes as direct application, spray drift, run-off drainage, waste disposal, industrial, domestic or agricultural effluent and atmospheric deposition and may be transformed in those waters by chemical (e.g., hydrolysis, oxidation etc.), photochemical and/or microbial processes. Hydrolysis test methods are presented separately. Photolysis in air was evaluated following procedures published for soil fumigants (referenced below: Moilanen et al., 1978). The experiments were performed to determine the rate of cyanogen decomposition in air inside a closed 160-mL bottle. In the dark at 21.5 ± 2.5°C, the half-life of cyanogen was 150 days, at 25 ± 2°C under continuous UV light (1500-2500 µw/cm^2), the half-life was reduced to 98 days. Photolysis in air was evaluated following procedures published for soil fumigants (referenced below: Moilanen et al., 1978) with these exceptions: 1)     The incubation temperature stated in the protocol is 23 ± 2^oC for both dark and light incubation. In this study, the incubation temperature was 21.5 ± 2.5°C for the dark incubator and 25 ± 2°C. Impact on the study: None. Temperature in the study range has no significant effect of cyanogen degradation. 2)     The degradation products were not identified due to the slow degradation process.  Impact on the study: None. The concentrations of the degradation products were very small and accurate measurements were not possible. Degradation products were identified in a separate study. Compliance: This study was conducted following the United States Environmental Protection Agency (EPA) Good Laboratory Practice Standards (40 CFR Part 160), 16 October 1989, the Organisation for Economic Cooperation and Development (OECD) Principles of Good Laboratory Practice[C(97) 186/Final], 26 November 1997; and the standard operating procedures of Ajwa Analytical Laboratories, LLC, and the protocol as approved by the Sponsor with the following exceptions: Ajwa Analytical Laboratories, LLC was not certified by the OECD. However, GLP-compliant equipment was used by GLP-trained staff from University of California-Davis and Ajwa Analytical Laboratories, LLC. Signed and dated GLP, Quality Assurance and Data Confidentiality statements were provided. Conclusion:

Cyanogen is stable in air; the half-life is 98 days at 25±2°C under UV light and 151 days at 21.5±2.5°C in the dark. This study used continuous light over24-hourperiod. However, direct sunlight has higher intensity (measured UVA and UVB intensity of 9000 µW/cm²) and cyanogen may degrade at a faster rate under direct sunlight, especially if the air has high relative humidity. Hydrolysis in water (under light and in the dark) was conducted in a different study

Description of key information

Cyanogen is reactive and does not persist in the environment unchanged (EPA 1978c, ATSDR 2006). One of possible degradation pathways is hydrolysis in the atmosphere. Cyanogen reacts with water to yield hydrogen cyanide and cyanic acid (HOCN) (Yngard 2008, EPA 1979, ATSDR 2006). Cyanogen is stable in air; the half-life is 98 days at 25±2°C under UV light and 151 days at 21.5±2.5°C in the dark. This study used continuous light over 24-hour period. However, direct sunlight has higher intensity (measured UVA and UVB intensity of 9000 µW/cm2) and cyanogen may degrade at a faster rate under direct sunlight, especially if the air has high relative humidity. Based on physical-chemical properties, most of the cyanogen used during fumigation is released into the atmosphere. Cyanogen also reacts with hydroxyl radicals in the gas phase (Atkinson 1989) however, based on the range constant and assuming average concentration of hydroxyl radicals, the residence time for the reaction of cyanogen with hydroxyl radical in the atmosphere is about 25 years. The reaction of cyanogen with OH-radical has been also calculated by atmospheric oxidation program (AOP), a model included in the Estimation Program Interface (EPI), U.S. Environmental Protection Agency, Washington, DC. Time of persistence, transport potential (CTD) – km and distribution between compartments for various emission scenario (emission to air, water or soil) and other parameters are described in LRTP model. For ethanedinitrile, overall persistence time (Pov) is 98 days (based on persistence time in air) and travel distance is 32 868 km. When there is emission of ethanedinitrile to air only, most of the compound (99.96%) remains in air and only 0.03% is transported to water and only 0.01% is transported to soil. Thus, ethanedinitrile is transported to long distances, however, remains mostly in air. In EQC model, most of ethanedinitrile which is emitted to air (as it is in our case) remains in air and only minor amounts are transported to water, soil or sediment. Concentrations in environmental compartments are very low compared to concentrations that present risk for nature or humans.

Key value for chemical safety assessment

Half-life in air:

98 d