Cyanamide

Endpoint summary

Description of key information

Stability of cyanamide in the air

According to the Atkinson calculation cyanamide was estimated to be 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 which is chemically far away from typical organic molecules like phenols or halogen-hydrocarbons, for which the model seems to be better suited.

 

Stability of cyanamide in water

The hydrolytic degradation of cyanamide under sterile conditions is both temperature and pH dependent. At 25°C cyanamide was hydrolytically stable, regardless of the pH values.

 

Stability of cyanamide in soil

Two studies examined the phototransformation of cyanamide in soil. In the newer higher Tier soil photolysis that was conducted under more realistic conditions, no major metabolites of cyanamide were encountered and cyanamide was almost completely mineralised to CO2 in both irradiated and dark control samples.

Additional information

Stability of cyanamide was examined in air, water and soil. Phototransformation in air was evaluated by an estimation method, namely a calculation according to Atkinson. Stabilty in water was experimentally investigated by a hydrolysis study and a photolysis study. Two studies examined the phototransformation in soil.

 

Stability of cyanamide in the air

According to the Atkinson calculation the overall rate constant for cyanamide was estimated to be 0.0 cm³ molecule-1 sec-1. cyanamide was therefore estimated to be stable in the atmosphere. Cyanamide is not supposed to react with hydroxyl radicals and ozone. 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 which is chemically far away from typical organic molecules like phenols or halogen-hydrocarbons, for which the model seems to be better suited.

 

Stability of cyanamide in water

The hydrolytic stability of cyanamide was studied in aqueous solutions buffered at pH values of 5, 7 and 9. Solutions containing cyanamide were prepared at nominal concentrations of 100 µg/mL and were incubated for up to 720 hours (30 days) at different temperature and pH in the dark. The hydrolytic degradation of cyanamide under sterile conditions is both temperature and pH dependent. At 25°C cyanamide was hydrolytically stable, regardless of the pH values, therefore, additional tests were performed at higher temperatures (50/65 °C and 80 °C). With increasing temperature and pH value of the buffer solutions cyanamide was degraded with DT50 values of 1100 h (pH 5), 563 h (pH 7), 302 h (pH 9) at 50°C and 60.7 h (pH 5), 147 h (pH 7) and 7.2 h (pH 9) at 80°C. Photolysis of cyanamide is a more significant degradation pathway at pH 5 and pH 7 (25°C) than hydrolysis. The photolytical half-life of cyanamide in buffered aqueous solutions was calculated to be 28.9 days and 38.5 days at pH 5 and pH 7. Urea was detected as major degradation product in the light exposed samples (Urea was also detected in the pH 5 dark control samples at concentrations up to 8.18 % of IMD).

 

Stability of cyanamide in soil

Two studies examined the phototransformation of cyanamide in soil. In the newer higher Tier soil photolysis that was conducted under more realistic conditions, no major metabolites of cyanamide were encountered and cyanamide was almost completely mineralised to CO2 in both irradiated and dark control samples. The degradation of cyanamide was fast both in irradiated and in the dark samples with DT50 values of 2.4 and 2.0 h, respectively, indicating that the rate of degradation due to photolysis is negligible compared to the rate of degradation caused by biodegradation.