Calcium cyanamide

Phototransformation in air

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

phototransformation in air

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Study period:

2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Qualifier:

no guideline required

Principles of method if other than guideline:

For details on method see below (model calculation)

GLP compliance:

no

Remarks:

study is a model calculation.

Estimation method (if used):

The photo-chemically and oxidative decomposition of cyanamide in air was evaluated based on a theoretical calculation according to Atkinson.
The calculation was performed with the help of the programme AOPWIN, Atmospheric Oxidation Programme v1.90 for Microsoft Windows 3.1, Windows 95/98, Windows NT (© 2000 US Environmental Agency).

Light source:

other: not applicable

Details on light source:

Not applicable

Details on test conditions:

Not applicable

Reference substance:

no

Preliminary study:

Not applicable

Test performance:

Not applicable

Results with reference substance:

Not applicable

Model results: The total OH radical reaction rate constant (kOH) is given by: kOH = k (H-atom abstraction from C-H and O-H bonds) + k (OH radical addition to CC double and triple bonds) + k (OH radical addition to aromatic rings) + k (OH radical interaction with N-, S- and OH-containing groups) For cyanamide it is: kOH = k (OH radical interaction with N bonds) The reaction rates with the amino group of cyanamide (OH radical interaction with N containing groups) have a value of k = 0.0000 × 10-12 cm3 molecule^-1 sec^-1. That means, that for cyanamide the OH radicals do not react with the N containing groups and therefore, the overall rate constant was estimated to be 0.0 cm3 molecule^-1 sec^-1.

Validity criteria fulfilled:

not applicable

Conclusions:

Cyanamide was estimated to be stable in the atmosphere. Cyanamide is not supposed to react with hydroxyl radicals and ozone

Executive summary:

An estimation of the photochemical degradation of cyanamide was performed using the Atkinson calculation method. The reaction rates with the amino group of cyanamide (OH radical interaction with N containing groups) have a value of k = 0.0000 × 10-12 cm3 molecule^-1 sec^-1. That means, that for cyanamide the OH radicals do not react with the N containing groups and therefore, the overall rate constant was estimated to be 0.0 cm3 molecule^-1 sec^-1.

It can therefore be concluded that cyanamide is stable in the atmosphere. It is, however, questionable whether the Atkinson calculation allows for an adequate estimation of the photochemical degradation of cyanamide. It has to be considered that cyanamide is a substance that is chemically far away from typical organic molecules like phenols or halogen-hydrocarbons, for which the model seems to be better suited.

Reference 2

Endpoint:

phototransformation in air

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Available data for the phototransformation of hydrogen cyanamide in air are used in a read-across approach for the assessment of calcium cyanamide:
Upon dissolution in water calcium cyanamide is fast transformed to hydrogen cyanamide. Thus, upon release of calcium cyanamide via wastewater streams in relation to industrial manufacture and use, the environmental distribution and exposure is driven by the physico-chemical/fate properties of cyanamide.
For the agricultural application of calcium cyanamide the substance is formulated in a slow dissolving granule (PERLKA). Calcium cyanamide technical grade has a melting point of 1145-1217°C and thus a negligible vapour pressure. In contact with soil moisture, PERLKA granules will slowly release hydrogen cyanamide. Thus, any potential air exposure will be driven by cyanamide, not calcium cyanamide.

For detailled description where read across is used/recommended and where it is preferrable to refain from read across, please see section 13.2 "read across justification for environmental endpoints" and "Scientific rationale for not using cyanamide as read-across substance for calcium cyanamide on toxicological endpoints"

Reason / purpose for cross-reference:

read-across source

Preliminary study:

Not applicable

Test performance:

Not applicable

Results with reference substance:

Not applicable

Model results: The total OH radical reaction rate constant (kOH) is given by: kOH = k (H-atom abstraction from C-H and O-H bonds) + k (OH radical addition to CC double and triple bonds) + k (OH radical addition to aromatic rings) + k (OH radical interaction with N-, S- and OH-containing groups) For cyanamide it is: kOH = k (OH radical interaction with N bonds) The reaction rates with the amino group of cyanamide (OH radical interaction with N containing groups) have a value of k = 0.0000 × 10-12 cm3 molecule^-1 sec^-1. That means, that for cyanamide the OH radicals do not react with the N containing groups and therefore, the overall rate constant was estimated to be 0.0 cm3 molecule^-1 sec^-1.

Validity criteria fulfilled:

not applicable

Conclusions:

Hydrogen cyanamide was estimated to be stable in the atmosphere. Hydrogen cyanamide is not supposed to react with hydroxyl radicals and ozone.

Available data for the phototransformation of hydrogen cyanamide in air are used in a read-across approach for the assessment of calcium cyanamide:
Upon dissolution in water calcium cyanamide is fastsly transformed to hydrogen cyanamide. Thus, upon release of calcium cyanamide via wastewater streams in relation to industrial manufacture and use, the environmental distribution and exposure is driven by the physico-chemical/fate properties of hydrogen cyanamide.
For the agricultural application of calcium cyanamide the substance is formulated in a slow dissolving granule (PERLKA). Calcium cyanamide has a melting point of 1145-1217°C and thus a negligible vapour pressure. In contact with soil moisture, PERLKA granules will slowly release hydrogen cyanamide. Thus, any potential air exposure will be driven by hydrogen cyanamide, not calcium cyanamide.

For detailled description where read across is used/recommended and where it is preferrable to refain from read across, please see section 13.2 "read across justification for environmental endpoints" and "Scientific rationale for not using cyanamide as read-across substance for calcium cyanamide on toxicological endpoints"

Executive summary:

An estimation of the photochemical degradation of cyanamide was performed using the Atkinson calculation method. The reaction rates with the amino group of cyanamide (OH radical interaction with N containing groups) have a value of k = 0.0000 × 10-12 cm³ molecule^-1 sec^-1. That means, that for cyanamide the OH radicals do not react with the N containing groups and therefore, the overall rate constant was estimated to be 0.0 cm³ molecule^-1 sec^-1.

It can therefore be concluded that cyanamide is stable in the atmosphere. It is, however, questionable whether the Atkinson calculation allows for an adequate estimation of the photochemical degradation of cyanamide. It has to be considered that cyanamide is a substance that is chemically far away from typical organic molecules like phenols or halogen-hydrocarbons, for which the model seems to be better suited.

This information is used in a read-across approach in the assessment of the target substance.

For detailled description where read across is used/recommended and where it is preferrable to refain from read across, please see section 13.2 "read across justification for environmental endpoints" and "Scientific rationale for not using cyanamide as read-across substance for calcium cyanamide on toxicological endpoints"

Description of key information

Cyanamide was estimated to be stable in the atmosphere and is thus not expected to react with hydroxyl radicals and ozone.

Additional information

Available data for the phototransformation of cyanamide in air are used in a read-across approach for the assessment of calcium cyanamide:

Upon dissolution in water calcium cyanamide is fast transformed to hydrogen cyanamide. Thus, upon release of calcium cyanamide via water in relation to industrial manufacture and use, the environmental distribution and exposure is driven by the physico-chemical/fate properties of cyanamide.

For the agricultural application of calcium cyanamide the substance is formulated in a slow dissolving granule (PERLKA). Calcium cyanamide has a melting point of 1145-1217 °C and thus a negligible vapour pressure. In contact with soil moisture, PERLKA granules will slowly release cyanamide. Thus, any potential air exposure will be driven by cyanamide, not calcium cyanamide.

For detailed description where read across is used/recommended and where it is preferable to refrain from read across, please see section 13.2 "read across justification for environmental endpoints" and "Scientific rationale for not using cyanamide as read-across substance for calcium cyanamide on toxicological endpoints"