Guanidinium nitrate

Endpoint summary

Description of key information

Hydrolysis: 

Based on hydrolysis of a structural analog substance a hydrolysis half live of > 1 year was deducted

  

Photodegradation

Due to the low vapour pressure the substance under investigation will not be present in the gas phase in the atmosphere in appreciable amounts and therefore the elimination path photodegradation in air will be only of minor importance.

 

Biodegradation: 

Guanidine nitrate is inherently biodegradable. This was proved in a non guideline study (Mitchell 1987). Test conditions especially test substance concentration and bacteria concentration are comparable to a OECD301 guideline study, inoculum is expected to be adapted. Guanidinenitrat is also biodegradable under less favourable conditions as was demonstrated in degradation tests with 14-C Guanidine in river water and aerated soil.

Degradation tests with 8 river water samples from different locations showed a mean degradation half life for guanidine of 5.25 d at 25°C after a mean lag phase of 30 d.

 

The salt Guanidine nitrate consists of the Guanidinium-Cation and Nitrate-Anion. Nitrate-salts are widely used as Nitrogen plant fertilizers. Plants metabolize the Nitrate-anioin for their nitrogen nutrition and thus quickly reduze it's concentration in soils and water as long as the Nitrate concentration doesn't reach toxic levels.

The river water die away test showed that the development of the microbial populations capable of enhanced guanidinium mineralization is related to the concentration of the cation. At the three highest concentrations (0.1 - 10 mg/l), a biodegrading population developed that ultimately effected the persistence of the 14-C guanidinium cation. Mineralization occurred also at 3 guanidinium concentrations tested from 0.0005 - 0.01 mg/l but not with a similar extensive mineralization rate as at 0.1 - 10 mg/ Guanidinium /L and mineralization rate developed more slowly as at 0.1 mg/L.

Both from direct observations in surface water samples (other experiments in the publication) and from the evaluation of an enriched laboratory population, the development of such a population as well as its degradation of guanidinium would likely be slow.

14-C Guanidinium in aerated soil is biodegraded with a half live of 2.5 - 8 days for guanidine concentrations of 2.5 – 100 mg/kg dw. The degradation rate is dependent on the concentration of guanidinium with a lower degradation rate at high concentrations, on the type of soil used and on the availability of carbon sources (Glucose or Cellulose) which enhance mineralization rate. Nitrogen in form of Ammonium, Nitrate, Nitroguanidine only slightly inhibit guanidinium mineralization.

 

Bioaccumulation:

In accordance with column 2 of REACH Annex IX, the study on bioaccumulation (required in section 9.3.2) does not need to be conducted as the substance has a low potential for bioaccumulation (measured log Kow < -1.7).

 

Transport and distribution:

In accordance with REACH Annex IX, the study on "Further information on adsorption/desorption" (required in section 9.3.3) does not need to be conducted as the substance has a low potential for bioaccumulation (measured log Kow < -1.7).