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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil: simulation testing
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
RA study
Justification for type of information:
Refer to the section 13 for details on the read across justification. The biodegradation study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.
Reference:
Composition 1
Principles of method if other than guideline:
The study comprised two treatments - test substance and chemical blank control, each with three replicates - and was carried out in biometers containing approximately 50 g dry weight equivalents of soil. The test substance was added in appropriate amounts of deionised water not exceeding that required for bringing the soils to 50 to 70% of the maximum moisture capacity. The amount of water to remoisturize 50 g of soil to approximately 60% of its maximum field capacity was determined from the data of the moisture content of the soil after air-drying and the maximum field moisture capacity. The soils were maintained at this moisture level by the addition of deionised water, when necessary. Loam was added to the biometers after the test solutions to facilitate moistening of the soils uniformly by capillary action. Test substance was added at a concentration of 10 mg carbon per 50 g soil. The side tube of the biometer contained 20 mL 0.2 M KOH for absorbing carbon dioxide produced by the microorganisms. The test was incubated at 22 ± 3°C and run for approximately 90 d. The theoretical CO2 production of the test substance was calculated from its carbon content. The amounts of carbon dioxide produced was calculated by subtracting the mean carbon dioxide production in the test systems containing the test substance and the mean carbon dioxide production level in the control blank. Biodegradation was calculated as the ratio of experimental carbon dioxide production to theoretical carbon dioxide production [ThCO2P].
GLP compliance:
no
Test type:
laboratory
Test material information:
Composition 1
Specific details on test material used for the study:
- Purity: 50% (in water)
Oxygen conditions:
aerobic
Soil classification:
other: loam
Key result
% Degr.:
64
Parameter:
CO2 evolution
Sampling time:
70 d
Key result
Half-life:
40 d
Remarks on result:
other: DT50
Transformation products:
no
Details on results:
The test substance was biodegraded in loam. The percentage reached at Day 70 was 64. This percentage of the theoretical carbon dioxide production presumes complete mineralisation. The DT50 was estimated to be 40d.

Conclusions:
Based on the results of the read across study, the test substance was 64% biodegraded in loam at Day 70. This percentage of the theoretical carbon dioxide production presumes complete mineralisation. The DT50 was estimated to be 40 days.
Executive summary:

A study was conducted to determine the biodegradation of the read across substance, quaternary ammonium compounds, benzyl C12-C16 (even numbered)-alkyldimethyl chlorides (C12-16 ADBAC), in a loamy soil. The study comprised two treatments - test substance and chemical blank control, each with three replicates - and was carried out in biometers containing approximately 50 g dry weight equivalents of soil. The test substance was added in appropriate amounts of deionised water not exceeding that required for bringing the soils to 50 to 70% of the maximum moisture capacity. The soils were maintained at this moisture level by the addition of deionised water, when necessary. Loam was added to the biometers after the test solutions to facilitate uniform moistening of the soils by capillary action. Test substance was added at a concentration of 10 mg carbon per 50 g soil. The side tube of the biometer contained 20 mL 0.2 M KOH for absorbing carbon dioxide produced by the microorganisms. The test was incubated at 22 ± 3°C and run for approximately 90 d. The theoretical CO2 production of the test substance was calculated from its carbon content. The amounts of carbon dioxide produced was calculated by subtracting the mean carbon dioxide production in the test systems containing the test substance and the mean carbon dioxide production level in the control blank. Biodegradation was calculated as the ratio of experimental carbon dioxide production to theoretical carbon dioxide production [ThCO2P]. Based on the results of the read across study, the test substance was 64% biodegraded in loam at Day 70. This percentage of the theoretical carbon dioxide production presumes complete mineralisation. The DT50 was estimated to be 40 days (van Ginkel, 1994).

Description of key information

Key value for chemical safety assessment

Half-life in soil:
40 d

Additional information

A study was conducted to determine the biodegradation of the read across substance, quaternary ammonium compounds, benzyl C12-C16 (even numbered)-alkyldimethyl chlorides (C12-16 ADBAC), in a loamy soil. The study comprised two treatments - test substance and chemical blank control, each with three replicates - and was carried out in biometers containing approximately 50 g dry weight equivalents of soil. The test substance was added in appropriate amounts of deionised water not exceeding that required for bringing the soils to 50 to 70% of the maximum moisture capacity. The soils were maintained at this moisture level by the addition of deionised water, when necessary. Loam was added to the biometers after the test solutions to facilitate uniform moistening of the soils by capillary action. Test substance was added at a concentration of 10 mg carbon per 50 g soil. The side tube of the biometer contained 20 mL 0.2 M KOH for absorbing carbon dioxide produced by the microorganisms. The test was incubated at 22 ± 3°C and run for approximately 90 d. The theoretical CO2 production of the test substance was calculated from its carbon content. The amounts of carbon dioxide produced was calculated by subtracting the mean carbon dioxide production in the test systems containing the test substance and the mean carbon dioxide production level in the control blank. Biodegradation was calculated as the ratio of experimental carbon dioxide production to theoretical carbon dioxide production [ThCO2P]. Based on the results of the read across study, the test substance was 64% biodegraded in loam at Day 70. This percentage of the theoretical carbon dioxide production presumes complete mineralisation. The DT50 was estimated to be 40 days (van Ginkel, 1994).