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Environmental fate & pathways

Biodegradation in soil

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Endpoint:
biodegradation in soil: simulation testing
Data waiving:
study technically not feasible
Justification for data waiving:
other:
Endpoint:
biodegradation in soil
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
secondary literature
Remarks:
The assessment contains a summary of relevant studies concerning biotic or abiotic degradation in soil and water.
Principles of method if other than guideline:
Effect of hydrazine on microbial activity not known. Therefore, degradation rates and effects on microorganisms determined.
GLP compliance:
not specified
Test type:
laboratory
Oxygen conditions:
aerobic
Soil classification:
not specified
Soil no.:
#1
Soil type:
other: Non-sterile Arredondo fine sand. Clay content assumed to be very low, it is fine sand primarily.
% Org. C:
1.7
Details on soil characteristics:
Inoculum concentration or number of microorganisms: 1 Cfu/g soil
Duration:
8 d
No.:
#1
Details on transformation products:
No evidence of ammonia produced via degradation.
Conclusions:
Hydrazine concentrations were monitored in sterile and non-sterile Arredondo fine sand. Autooxidation appeared to be the principal factor contributing to the disappearance of the chemical from the soil, as less than 3% of applied hydrazine at a concentration of 10 μg/g soil was recovered from sterile soil. By comparing the hydrazine loss from sterile and non-sterile soils, it appeared that biological degradation was responsible for about 20% of
the degradation.
Executive summary:

Half-life in soil were reported to be in the range of <4E-02 days (10 µg/g)

0.5 days (100 µg/g)

3 days (500 µg/g) at 25°C.

It is assumed that at higher concentrations bacteria were killed based on the toxic effects of hydrazine to bacteria.

Description of key information

Standard OECD test guidelines are not applicable to inorganic chemicals such as Hydrazine.

Key value for chemical safety assessment

Additional information

One older study (Ou et al 1987) was discussed by Environmental Canada 2011.

Hydrazine concentrations were monitored in sterile and non-sterile Arredondo fine sand. Autooxidation appeared to be the principal factor contributing to the disappearance of the chemical from the soil, as less than 3% of applied hydrazine at a concentration of 10 μg/g soil was recovered from sterile soil. By comparing the hydrazine loss from sterile and non-sterile soils, it appeared that biological degradation was responsible for about 20% of the degradation.

Half-life times of <4E-02 days (10 µg/g), 0.5 days (100 µg/g) and 3 days (500 µg/g) were reported. It is however assumed that at higher concentrations bacteria were killed based on the toxic effects of hydrazine to bacteria. The result based on 100 µg/g is, although a very high loading, is considered as worst case yielding a half-life of 0.5 days.