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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: screening tests
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
see "General Justification for Read-Across" attached to IUCLID section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Mutual read across from the AAPBs to one another is justified:

a) Based on the information given in section 1, it can be concluded that all AAPBs mentioned above are similar in structure, since they are manufactured from similar resp. identical precursors under similar conditions and all contain the same functional groups. Thus a common mode of action can be assumed.
b) The content of minor constituents in all products are comparable and differ to an irrelevant amount.
c) The only deviation within this group of substances is a minor variety in their fatty acid moiety, which is not expected to have a relevant impact on intrinsic toxic or ecotoxic activity and environmental fate. Potential minor impact on specific endpoints will be discussed in the specific endpoint sections.

The read-across hypothesis is based on structural similarity of target and source substances. Based on the available experimental data, including key physico-chemical properties and data from toxicokinetic, acute toxicity, irritation, sensitisation, genotoxicity and repeated dose toxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all five substances.
The respective data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see "General Justification for Read-Across" attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see "General Justification for Read-Across" attached to IUCLID section 13

4. DATA MATRIX
see "General Justification for Read-Across" attached to IUCLID section 13
Reason / purpose:
read-across: supporting information
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Test performance:
The study was conducted according to ECETOC Anaerobic Biodegradation (Technical Report No. 28). Deviations from guideline were not reported.
Parameter:
% degradation (DOC removal)
Value:
ca. 80
Sampling time:
62 d
Parameter:
other: biogas production and TIC
Value:
>= 80 - <= 90
Sampling time:
60 d
Validity criteria fulfilled:
yes
Interpretation of results:
other: biodegradable under anaerobic conditions
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
see "General Justification for Read-Across" attached to IUCLID section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Mutual read across from the AAPBs to one another is justified:

a) Based on the information given in section 1, it can be concluded that all AAPBs mentioned above are similar in structure, since they are manufactured from similar resp. identical precursors under similar conditions and all contain the same functional groups. Thus a common mode of action can be assumed.
b) The content of minor constituents in all products are comparable and differ to an irrelevant amount.
c) The only deviation within this group of substances is a minor variety in their fatty acid moiety, which is not expected to have a relevant impact on intrinsic toxic or ecotoxic activity and environmental fate. Potential minor impact on specific endpoints will be discussed in the specific endpoint sections.

The read-across hypothesis is based on structural similarity of target and source substances. Based on the available experimental data, including key physico-chemical properties and data from toxicokinetic, acute toxicity, irritation, sensitisation, genotoxicity and repeated dose toxicity studies, the read-across strategy is supported by a quite similar toxicological profile of all five substances.
The respective data are summarised in the data matrix; robust study summaries are included in the Technical Dossier in the respective sections.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
see "General Justification for Read-Across" attached to IUCLID section 13

3. ANALOGUE APPROACH JUSTIFICATION
see "General Justification for Read-Across" attached to IUCLID section 13

4. DATA MATRIX
see "General Justification for Read-Across" attached to IUCLID section 13
Reason / purpose:
read-across: supporting information
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Oxygen conditions:
aerobic
Duration of test (contact time):
28 d
Key result
Remarks on result:
other: readily biodegradable based on read-across
Interpretation of results:
readily biodegradable

Description of key information

Experimental results from several guideline studies (e. g. OECD 301 A, 301 B, 301 D, 301 E) on the aerobic biodegradation of Coco AAPB, C12 AAPB and C8-18 AAPB are available.
The inherent biodegradability of C12-18 AAPB was proven in a Zahn-Wellens Test. The anaerobic biodegradability of Coco AAPB and C8-18 AAPB was investigated in studies conducted similar to OECD guideline 311.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

No data are available for the target substance C12 -14 AAPB. A Zahn-Wellens/EMPA Test on inherent biodegradability is available for the source substance C12 -18 AAPB. Aerobic as well as anaerobic biodegradation screening tests on ready biodegradation are available for the source substances C8-18 AAPB and C8-18 and C18 unsatd. AAPB (Coco AAPB). A justification for read-across is given in IUCLID section 5.2.

 

Aerobic biodegradation

C8 -18 and C18 unsatd. AAPB

A variety of different screening studies for C8-18 and C18 unsatd. AAPB are available, confirming the readily biodegradability. One reliable study (Klimisch 1) was selected as key study and described in more detail.

 

The ready biodegradability of C8-18 and C18 unsatd. AAPB was investigated in a study conducted according to EPA OPPTS 835.3120 (Sealed Vessel Carbon Dioxide Production Test) and ISO/DIS 14593 over a period of 28 days and using activated sludge as inoculum. The biodegradation rate was determined by measurement of CO2 evolution. Inoculum blank and procedural/functional control with the reference substance sodium benzoate performed.

C8-18 and C18 unsatd. AAPB proved to be readily biodegradable and fulfilling the 10 -d window criterion (87.2% biodegradation after 28 d). The functional control reached the pass level >60% after 14 d.

 

Experimental results from several guideline studies (e. g. OECD 301 A, 301 B, 301 D, 301 E) on the aerobic biodegradation of Coco AAPB are available. The following results were obtained from studies fulfilling the validity criteria: (ISO/DIS 14593: 87.2 - 93 % biodegradation after 28 d; DOC Die-Away Test: 92 % degradation after 28 d; ; Closed-Bottle-Test: 86 % degradation after 28 d; Modified OECD Screening Test: 100 % biodegradation after 28 d). (Data are summariesed in an overview table in Annex I).

 

C12 AAPB

The ready biodegradability of C12 AAPB was investigated in a study conducted according to EU Method C.4-F (Determination of the "Ready" Biodegradability - MITI Test) over a period of 28 days and using an inoculum taken from a purifying plant for municipal and industrial effluents, from an industrial effluent purifying plant and surface water and surface soil from a river bank. The biodegradation rate was determined by measurement of oxygen consumption. Inoculum blank and procedural/functional controls with the reference substance sodium benzoate were performed. In deviation from guideline 2 instead of 3 bottles containing test material and inoculum were used. Furthermore, a bottle containing test substance in water only was not included in the tests. The test item proved to be readily biodegradable. After 28 days the percentage of biodegradability was 82 % based on ThOD (ThOD=0.7 mg O2/mg; ThOD not further specified: ThODNH4 or ThODNO3) and 95 % based on COD (COD=0.60 mg O2/mg). The functional control reached the pass level > 60 % after 14 d.

 

C12 -18 AAPB

The inherent biodegradation of C12 -18 AAPB was investigated in a study conducted according to DIN 38 412, Part 25 (1984) and which is equivalent or similar to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test) over a period of 15 days and using non-adapted industrial activated sludge as inoculum. The substance proved to be inherently biodegradable (elimination: 90.8 % after 15 d; biodegradation: 89.4 % after 15 d). The adsorption to sludge was determined to 13 % after 3 h. The reference substance diethylene glycol was biodegraded by 96.6 % after 8 d. Based on these results it can be assumed that C12 -18 AAPB will be readily biodegradable in OECD Guideline tests on ready biodegradation. This assumption is supported by Zahn-Wellens tests with Coco AAPB where similar results were obtained and the ready biodegradability could be shown.

 

C8 -18 AAPB

C8 -18 AAPB proved to be readily biodegradable. In a study conducted according to OECD Guideline 301 B (Ready Biodegradability: CO2Evolution Test) over a period of 28 days and using activated sludge obtained from a municipal wastewater treatment plant as inoculum, the test substance was biodegraded by 91.6 % after 28 d (10 d window criterion fulfilled). These results were supported by a further guideline study. In a supporting study conducted according to EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test), the test substance was biodegraded by 76.3 % after 28 d).

 

Anaerobic biodegradation

The anaerobic biodegradability of C8-18 and C18 unsatd. AAPB was investigated in a study conducted according to ISO11734 (Water quality - Evaluation of the ultimate anaerobic biodegradability of organic compounds in digested sludge - Method by measurement of the biogas production) and equivalent or similar to OECD Guideline 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge: Measurement of Gas Production) over a period of 60 days and using non-adapted digester sludge as inoculum. The biodegradation rate was determined by measurement of total biogas production. Inoculum blank and procedural/functional controls with the reference substance polyethylene glycol 400 were performed. The test item proved to be biodegradable under anaerobic conditions (total biodegradation: 80-90 % after 60 d). The functional control reached the pass level > 60 % after 60 d.

 

In a second study the anaerobic biodegradability of C8 -18 AAPB was investigated in a study conducted according to ECETOC Anaerobic Biodegradation (Technical Report No. 28; similar to OECD guideline 311) over a period of 62 days and digested sludge as inoculum.The biodegradation rate was determined by measurement of gas production and TIC. Inoculum blank, procedural/functional control with the reference substance sodium benzoate and toxicity control were performed. Deviations from guideline were not reported.

The test item proved to be well biodegradable under anaerobic conditions (ca. 80% after 62 d).The functional control reached the pass level >70% (80% after 62 d). In the toxicity control containing both test and reference item an inhibitory effect of the test item on the anaerobic biodegradation was not observed.

 

Conclusion

Experimental results from several guideline studies (e. g. OECD 301 A, 301 B, 301 D, 301 E) on the aerobic biodegradation of C8-18 and C18 unsatd. AAPB, C12 AAPB and C8 -18 AAPB are available. Based on the results, C8 -18 and C18 unsatd. AAPB, C12 AAPB, and C8 -18 AAPB can be regarded as readily biodegradable. The inherent biodegradability of C12-18 AAPB was proven in a Zahn-Wellens Test. Based on these results, the AAPBs can be regarded as readily biodegradable.

The anaerobic biodegradability of C8 -18 and C18 unsatd. AAPB and C8-18 AAPB was investigated in studies conducted similar to OECD guideline 311. Based on the results of these studies, the AAPBs are considered to be biodegradable under anaerobic condition.