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Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
Justification for type of information:
The supporting QMRF report has been attached
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Principles of method if other than guideline:
The data is predicted using the OECD QSAR toolbox version 3.3 with logKow as the primary descriptor.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material (as cited in study report): aluminum trioctadecanoate- Molecular formula (if other than submission substance): C18H36O2.1/3Al- Molecular weight (if other than submission substance): 877.3995 g/mol- Smiles notation (if other than submission substance): 1S/3C18H36O2.Al/c3*1-2-3-4-5-6-7-8-9-10-11-12-13-14-15-16-17-18(19)20;/h3*2-17H2,1H3,(H,19,20);/q;;;+3/p-3-InChI: CCCCCCCCCCCCCCCCCC(=O)[O-].CCCCCCCCCCCCCCCCCC(=O)[O-].CCCCCCCCCCCCCCCCCC(=O)[O-].[Al+3]- Substance type: Organic
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, adapted
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation:
CO2 evolution
Key result
Parameter:
% degradation (CO2 evolution)
Value:
76.75
Sampling time:
28 d
Remarks on result:
other: Other details not known
Details on results:
Test substance undergoes 76.75% degradation by CO2 evolution parameter in 28 days.

The prediction was based on dataset comprised from the following descriptors: "CO2 evolution"
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

(((((((((("a" or "b" or "c" or "d" or "e" )  and "f" )  and "g" )  and "h" )  and "i" )  and "j" )  and "k" )  and ("l" and ( not "m") )  )  and "n" )  and ("o" and "p" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Anionic Surfactants by US-EPA New Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Carboxylic acid by Organic Functional groups

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Carboxylic acid by Organic Functional groups (nested)

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Acid, aliphatic attach [-COOH] AND Alcohol, olefinic attach [-OH] AND Aliphatic Carbon [CH] AND Aliphatic Carbon [-CH2-] AND Aliphatic Carbon [-CH3] AND Carbonyl, aliphatic attach [-C(=O)-] AND Miscellaneous sulfide (=S) or oxide (=O) AND Olefinic carbon [=CH- or =C<] by Organic functional groups (US EPA)

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Carbonic acid derivative AND Carboxylic acid AND Carboxylic acid derivative by Organic functional groups, Norbert Haider (checkmol)

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 1) ONLY

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 2) ONLY

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 5) ONLY

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 6) ONLY

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Biodegrades Fast by Biodeg probability (Biowin 7) ONLY

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as days - weeks by Biodeg ultimate (Biowin 3) ONLY

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.3

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Radical OR Radical >> Generation of reactive oxygen species OR Radical >> Generation of reactive oxygen species >> Thiols by DNA binding by OASIS v.1.3

Domain logical expression index: "n"

Similarity boundary:Target: CCCCCCCCCCCCCCCCCC(O)=O
Threshold=40%,
Dice(Atom centered fragments)
Atom type; Count H attached; Hybridization

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 278 Da

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 306 Da

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
The test chemical aluminum trioctadecanoate was estimated to be readily biodegradable in water.
Executive summary:

Biodegradability of aluminum trioctadecanoate (CAS no. 637 -12 -7) is predicted using QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 76.75% degradation by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, the test chemical aluminum trioctadecanoate was estimated to be readily biodegradable in water.

Description of key information

Biodegradability of aluminum trioctadecanoate (CAS no. 637 -12 -7) is predicted using QSAR toolbox version 3.3 with logKow as the primary descriptor (2017). Test substance undergoes 76.75% degradation by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, the test chemical aluminum trioctadecanoate was estimated to be readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

1 predicted data for the target compound aluminum trioctadecanoate (CAS no. 637-12-7) and the total 4 weight of evidence studies (2 from peer reviewed journal and 2 from authoritative database) for its closest read across substance with logKow as the primary descriptor were reviewed for the biodegradation end point which are summarized as below:

 

In a predicted data done by SSS (2017) using QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical aluminum trioctadecanoate (CAS no. 637 -12 -7) was estimated.Test substance undergoes 76.75% degradation by CO2 evolution parameter in 28 days. Thus, based on percentage degradation, the test chemical aluminum trioctadecanoate was estimated to be readily biodegradable in water.

 

In a weight of evidence study from peer reviewed journal (Chemosphere, 1987) for read across substancecalcium stearate(CAS no. 1592-23-0),biodegradability of calcium stearate was assessed by OECD 301B guideline also known as Sturm test. Installations and equipment used in the test were as described in the OECD Guideline 301B. The size of the carbosys was reduced from 5 l to 3l and the volume of the solution from 2 to 1.5 l. A magnetic stirrer with a PTFE – coated rod of 6 cm length rotating at approximately 60 rpm was used for agitation. A constant temperature of 23°C was maintained by immersion of carbosys in a water bath. Sludge for the preparation of the inoculum was taken from a sewage treatment plant receiving predominantly domestic waste. The inoculum and the mineral solutions were prepared according to the OECD 301 guidelines.

In the method with direct dispersion of the test chemical, calcium stearate (20mg/l) was added as a powder or as a suspension in water prepared by ultrasonic dispersion, to the carbosys containing the inoculum. No additional treatment was given to the mixture containing the inoculum. In the method with solid carriers the samples were prepared by melting calcium stearate on glass filter papers. The glass filter papers were cut into small pieces before putting them into carbosys. The test chemical was biodegraded under all test conditions, fulfilling the strict criteria of ready biodegradability [60% within 10 days] except in one case where it was applied on a glass filter in a non-agitated container. The solubility of 2mg/l water was apparently sufficient to ensure the continuous availability of the test chemical to the bacteria. The decreased rate of biodegradation of the sample melted on the glass filter can be explained by a reduction in the availability of calcium stearate as a consequence of the melting operation [glazing of the surface] and the absence of agitation. The percentage degradation of test substance was determined to be 91% degradation by CO2 evolution parameterin 24 days in absence of agitation and glass filter paper was not used as a carried, whereas 99% degradation was observed by CO2 evolution parameter in 24 days in absence of agitation and 55 and 88% degradation was observed by CO2 evolution parameter in 24 days when glass filter papers was used as a carrier. In addition to this, test substance also undergoe degradation upto 72% and 84% in 20 days by CO2 evolution parameter using glass filter papers and ultrasound as a carrier and in presence of agitation. Thus, based percentage degradation, Calcium stearate was considered to be readily biodegradable in water.

 

Another supporting weight of evidence study of biodegradation for read across substancecalcium stearate(CAS no. 1592-23-0)was assessed by OECD 301C guideline also known as MITI test(Chemosphere, 1987). The test was carried out at 22±3°C in a HACH manometric respirometer according to OECD 301 C guidelines. The mineral solution was prepared according to the guidelines. Sludges for the preparation of the inoculum were obtained from domestic sewage treatment works, washed twice by centrifugation and resuspension in the test medium. These sludges were dispersed in the test medium to give a final activated sludge concentration of 30mg/l. Prior to the start of the test the bottles were incubated for 1 week at the test temperature to reduce the endogenous rate of the inoculum. The test chemical was added to the bottles to give a final concentration of 100mg/l Nonyphenol was used as an emulsifier. Blank tests were set up with the emulsifiers at the concentration used to correct the oxygen uptake. The test chemical is readily biodegradable under all test conditions, fulfilling the strict criterion of biodegradation [60% degradation in 10 days]. The percentage degradation of test substance was determined to be 91% degradation by BOD and ThOD parameterin 32 days. Thus, based on percentage degradation, Calcium stearate was considered to be readily biodegradable in nature.

 

In an additional study for the same read across substance calcium stearate(CAS no. 1592-23-0), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of test substance Calcium stearate (GSBL database, 2016). The study was performed according OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test).The percentage degradation of test substance was determined to be 95% degradation by ThOD or COD parameter in 28 days. Thus, based on percentage degradation, Calcium stearate was considered to be readily biodegradable in nature.

 

For read across substance Lead distearate (CAS no. 1072 -35 -1), biodegradation study was conducted for 14 days for evaluating the percentage biodegradability of substance Lead distearate (J-CHECK, 2016). Concentration of inoculum i.e, activated sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. When the test substance was esterified and a GC analysis was performed, the results contained Lead distearate and substances with fewer number of carbons, namely, Lead dipalmitate and Lead myristate. Degree of degradation of each substance was found to be Lead dipalmitate: 59.5%, Lead myristate: 67.7%. The percentage degradation of read across substance was determined to be 32.9 and 49.1% by BOD and GC parameter in 14 days. Thus, based on percentage degradation, Lead distearate is considered to be readily biodegradable in nature.

 

On the basis of above results for target chemicalaluminum trioctadecanoate (from OECD QSAR toolbox version 3.3) and for its read across substance (from peer reviewed journal and authoritative database J-CHECK and GSBL, 2016), it can be concluded that the test substance aluminum trioctadecanoate can be expected to be readily biodegradable in nature.