Quaternary ammonium compounds, C18 and C18 (unsaturated) alkyltrimethyl, chlorides

Biodegradation in soil

Link to relevant study record(s)

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

Justification for type of information:

Refer to the Quaternary ammonium salts (QAS) category or section 13 of IUCLID for details on the category justification.

Principles of method if other than guideline:

The aerobic biodegradation of the substance in loamy soil (at 10 mg carbon per 50 g soil) was determined by measuring carbon dioxide evolution in biometers for 90 days according to the US FDA Environmental Assessment Handbook, Technical Assistance Document 3.12 (1987). The amount of carbon dioxide (CO2) produced by the test substance was calculated by subtracting the mean CO2 production in the test systems containing the test substance and the mean CO2production level in the control blank. The biodegradation was calculated as the ratio of the experimental CO2 production to theoretical CO2 (ThCO2P which was based on the carbon content of the test substance).

GLP compliance:

no

Test type:

laboratory

Oxygen conditions:

aerobic

Soil classification:

other: loam

Details on soil characteristics:

COMPOSITION OF SOIL:
- %OM: 2.4
- % sand: 35.4
- % silt: 49.3
- % clay: 15.3
- CEC: 13.1 meq/100 g
- Additional substrate: No
- Test temperature: 22  3 degree C
- pH: 7.6
- Aeration of dilution water: No

Duration:

90 d

Initial conc.:

10 other: mg C per 50 g soil

Based on:

other: carbon

Parameter followed for biodegradation estimation:

CO2 evolution

Details on experimental conditions:

TEST SYSTEM:
- Culturing apparatus: Slightly modified biometers described by Bartha and Pramer. Both the Erlenmeyer and the side tube were closed with Mininert valves to enable direct sampling from the side tube and to provide pure oxygen in the Erlenmeyer. The Erlenmeyer and the side tube were fused together with an air- tight coupling so that the side tube and the Erlenmeyer could be weighed separately
- Number of culture flasks/concentration: 3
- Measuring equipment: Dohrmann DC-190 NPOC apparatus
- Test performed in closed vessels due to significant volatility of TS: No

INOCULUM:
- Nature: Loam
- Source: Heino, The Netherlands
- Sampling site: The soil was collected from below the litter layer
- Laboratory culture: No
- Preparation of inoculum for exposure: Stones and plant fragments were removed by hand. After collection the soil was air dried for approximately 2 days and sieved through a 2 mm sieve
- Pretreatment: No pretreatment, the soil was stored at room temperature in polyethylene bags until use in the experiment

SAMPLING: Once a week

STATISTICS:
The theoretical CO2 production of the test substance was calculated from the carbon content of the test substance. The amount of carbon dioxide produced by the test substance was calculated by subtracting the mean carbon dioxide production level in the control blank. The biodegradation was calculated as the ratio of experimental dioxide production to the theoretical carbon dioxide production (ThCO2P).

Key result

% Degr.:

64

Parameter:

CO2 evolution

Sampling time:

70 d

Key result

DT50:

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.

No validity criteria are available for this test, but the test was performed according to a standard guideline and therefore considered to be valid without restrictions.

Conclusions:

Under the study conditions, there was 64% degradation of the read across substance after 70 days. This percentage of the theoretical carbon dioxide production presumes complete mineralization. The DT50 was estimated to be 40 days

Executive summary:

A study was conducted to determine the aerobic biodegradation of the read across substance, C12-16 ADBAC (50% active in water) in loamy soil, according to the US FDA Environmental Assessment Handbook, Technical Assistance Document 3.12 (1987). The study comprised two treatments: test and chemical blank control group, each with three replicates. The read across substance was added into biometers at a concentration of 10 mg carbon per 50 g soil using appropriate amount of deionised water required for bringing the soils to 50-70% of the moisture capacity. Loam was added to the biometers after the test solutions to facilitate uniform moistening of the soils by capillary action. The test was then incubated at 22 ± 3°C and run for approximately 90 d. The side tube of the biometer contained 20 mL 0.2 M KOH for absorbing carbon dioxide produced by the microorganisms. The theoretical CO2 production of the read across substance was calculated from its carbon content. The amounts of carbon dioxide were calculated by subtracting the mean carbon dioxide production in the test systems containing the read across 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]. Under the study conditions, there was 64% degradation of the read across substance after 70 days. This percentage of the theoretical carbon dioxide production presumes complete mineralization. The DT50 was estimated to be 40 days (Ginkel, 1994). Based on the results of the read across study, similar degradation potential and half-life is considered for the test substance.  ​

Description of key information

Please note:A new better quality biodegradation study is available under the biocides consortium for C12-16 ADBAC substance. LoA discussions are ongoing with the data owners and it is expected to be completed soon. Another dossier update will be submitted as soon as this study is made available. The key results has been shared by the data owner to allow proceeding with risk assessment.

Based on the results of the read across study, the transformation of the C12 carbon chain of the test substance can be considered to be rapid with DT50 values ranging from 2.2-8.7 days with the SFO model and 1.6 – 7.2 days with the FOMC model.

Key value for chemical safety assessment

Half-life in soil:

8.7 d

at the temperature of:

20 °C

Additional information

Study 1: To ADD THE NEW SOIL BIODEGRADATION STUDY

Study 2:A study was conducted to determine the aerobic biodegradation of the read across substance, C12-16 ADBAC (50% active in water) in loamy soil, according to the US FDA Environmental Assessment Handbook, Technical Assistance Document 3.12 (1987). The study comprised two treatments: test and chemical blank control group, each with three replicates. The read across substance was added into biometers at a concentration of 10 mg carbon per 50 g soil using appropriate amount of deionised water required for bringing the soils to 50-70% of the moisture capacity. Loam was added to the biometers after the test solutions to facilitate uniform moistening of the soils by capillary action. The test was then incubated at 22 ± 3°C and run for approximately 90 d. The side tube of the biometer contained 20 mL 0.2 M KOH for absorbing carbon dioxide produced by the microorganisms. The theoretical CO2 production of the read across substance was calculated from its carbon content. The amounts of carbon dioxide were calculated by subtracting the mean carbon dioxide production in the test systems containing the read across 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]. Under the study conditions, there was 64% degradation of the read across substance after 70 days. This percentage of the theoretical carbon dioxide production presumes complete mineralization. The DT50 was estimated to be 40 days (Ginkel, 1994). Based on the results of the read across study, similar degradation potential and half-life is considered for the test substance.  ​

Based on the most recent and radiolabelled read across study in soil, the transformation of the C12 carbon chain of the test substance can be considered to be rapid with DT50 values ranging from 2.2-8.7 days with the SFO model and 1.6 – 7.2 days with the FOMC model.​