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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
12-11-2014 to 12-01-2015
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge: Measurement of Gas Production)
Version / remarks:
March 2006
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
anaerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
Digesting sludge from the municipal wastewater treatment plant Breisgauer Bucht was used as inoculum. The treatment plant clarifies predominantly domestic wastewater of the region of Freiburg and has a capacity of 600.000 inhabitant equivalents. Sampling date of activated sludge was November 6th 2014.
- Preparation of inoculum for exposure:
The inoculum was kept before use for 6 days under test conditions in order to reduce the blank values. It was then washed 3 times by centrifugation at 3000 g for 10min and decanting the supernatant, resuspending the sediment each time in anaerobic mineral medium.
- Concentration of sludge:
To determine the amount of total dry solids, three samples of digesting sludge were filtered (folded paper filters, diameter of 12.5 cm, Machery Nagel) and then dried at 105°C until the dry solids weight remained constant. The dry solid of the used sludge was determined as being 28.62 g/L.
- Initial cell/biomass concentration:
The measured IC after centrifugation and resuspendation in mineral medium (four times) was 16.07 mg/L. The calculated IC in the test vessel was therefore 1.6 mg/L.
Duration of test (contact time):
61 d
Initial conc.:
100 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
TEST SYSTEM
- Culturing apparatus: 600 ml serum bottles with chlorobutyl rubber septa and aluminium caps
- Method used to create anaerobic conditions: After filling and sealing the bottles, the oxygen in the headspace introduced by the filling process was replaced with nitrogen by inserting two syringe needles and blowing nitrogen gas through one of them for several seconds.
- Measuring equipment: Total carbon analyser TOC-5050A with autosampler ASI-5000A
- Other: Each test bottle was flushed with nitrogen gas for 60 seconds and immediately sealed with a rubber stopper. Afterwards bottles were shortly opened for the addition of appropriated amounts of the stock solutions of the test and reference items and immediately closed.
4400 mL deionised water was boiled for about 10min and allowed to cool down under a constant stream of nitrogen gas while being stirred on a magnetic stirrer. After reaching a temperature of 40°C the following stock solutions were added while mising: 10 mL of S1, 50 mL of S2, 50 mL of S3, 5 mL of S4 and 10 mL of S5. At a temperature of 40°C 500 mL of the washed digesting sludge was added (3.0 g/L dry solids final concentration). After about one minute of stirring, the test bottles were filled up to 450 mL each using a hose under a constant nitrogen gas stream. After filling and sealing the bottles, the oxygen in the headspace introduced by the filling process was replaced with nitrogen by inserting two syringe needles and blowing nitrogen gas through one of them for several seconds.
The test bottles were then transferred into a tempered water basin (35 +/- 2°C). After two hours the headspace pressure in the bottle was equalised to the atmosphere by inserting a syringe needle and gently pushing on the rubber stopper. The bottles were kept in the dark for 61 days. Two to three times a week all the bottles were shaken per hand. Headspace pressure was measured at least weekly. To do this the needle of the pressure meter was inserted through the seal of each bottle in turn. After recording the headspace pressure each time, the needle was detached from the pressure meter to allow equalisation before removal. At the end of the test IC and pH was determine in each bottle (day 61).

CONTROL AND BLANK SYSTEM
- Toxicity control: From a test item stock solution of 20 g/L 9.22 ml and from a reference item stock solution of 10 g/L 7.72 ml were added to the toxicity control flasks. This corresponds to a concentration of 200 mg TOC/L.

MEASURING OF IC
IC was measured using the TOC 5050 A with autosampler ASI 5000 A. This apparatus uses the method of non-dispersive infra-red detection of CO2 after stripping with H2PO3-addition. Samples were taken through the septum from the supernatant via syringes. Tubes containing 5 mL each were sealed with parafilm and placed into the autosampler. At the beginning, in the middle and at the end of the sample group a 100 ppm standard solution was tested to make sure the measuring points were valid.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
61
Sampling time:
61 d
Details on results:
The test item had a degradation extent of 61% in 61 days after considering the IC in the liquor (mean of four replicates). The degradation result refers to the active content of the test solution. The single degradation extents ranged from 48 to 73%. The pH at the end of the test was 6.8-6.9.
Results with reference substance:
The degradation of the reference item (sodium benzoate) started after a lag phase of 16 days and reached a degradation extent of 82% by day 61 (after considering the IC in the liquor, measurement of 4 flasks). The pH at the end of the test was 6.7 in the bottles.

No inhibition was observed in the toxicity control.

Validity criteria fulfilled:
yes
Interpretation of results:
other: biodegradable in anaerobic conditions
Conclusions:
The anaerobic degradation of the substance was investigated according to the OECD guideline 311. Withing 61 days, the biodegradation of the test item was 61% based on IC-measurement. Based on the cutoff value of 60%, the substance can be described as biodegradable in anaerobic conditions.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2005-05-25 - 2005-08-15
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
- Name of test material (as cited in study report): Oxidet L-75
- Identifiers: EC268-938-5, CAS68155-09-9
- Physical state: clear, colourless, slightly viscous liquid with an amine like odor
- Water solubility: Easily soluble in cold water
- Isomers composition: Not applicable
- Lot/batch No.: PHA007.1165
- Storage condition of test material: at room temperature
- Purity: 30% solution in water
- Expiry date: June 2007
- Storage condition of test material: 20 ± 5 ºC and in the dark
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): activated sludge from the sewage plant at Taunusstein-Bleidenstadt was washed twice with nutrient solution of the CO2 evolution test to eliminate organic components and carbonates from the sludge.
After resolution with mineral nutrient medium the sludge was aerated by means of compressed humidified air for about 4 hours. Before use as inoculum for the CO2 evolution test the sludge was homogenised in a Waring Blender at low speed for 2 min and then filtered through a cotton filter previously carefully rinsed with deionised water. The filtrate was used as inoculum (1% of the final volume of the test solution) on the same day of preparation.
Duration of test (contact time):
ca. 28 d
Initial conc.:
ca. 17 other: mg C/L
Based on:
test mat.
Reference substance:
benzoic acid, sodium salt
Key result
Parameter:
% degradation (CO2 evolution)
Value:
75
Sampling time:
28 d
Results with reference substance:
The control item sodium benzoate was degraded 84%. The 10-day window was met within 9 days (76%).

Results with sample 1:













































Time [d]mg CO2 generated in the test solution, cumulative% TCO2 (=% biodegradation)*
23.542
557.6327
9112.0652
18160.5274
22161.3774
28160.2574**
29162.8175***

*% TCO2: Percentage of total CO2 the test item has generated in relation to the thCO2


**The test solution was stopped by the addition of 1 mL conc. HCl


*** The difference between this titration and that before is due to the liberation of CO2 after acidification of the test solution


Results with sample 2:













































Time [d]mg CO2 generated in the test solution, cumulative% TCO2 (=% biodegradation)*
26.253
562.9629
9104.2148
18153.2070
22157.3272
28159.9174**
29161.7774***

*% TCO2: Percentage of total CO2 the test item has generated in relation to the thCO2


**The test solution was stopped by the addition of 1 mL conc. HCl


*** The difference between this titration and that before is due to the liberation of CO2 after acidification of the test solution


 

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item was tested for biodegradability according to the CO2 evolution test (OECD guideline 301B). Calculated from the organic carbon content of the test item and the measured CO2 generation, 75% of the theoretical CO2 (thCO2) has been generated by the test item within 28d of test period in the first culture with 274.8 mg of the test item. 74% of the theoretical CO2 has been generated by the test item within 28d in the second cutlure with 275.4 mg of the test item. The mean degradation value of the test item was 75%. The "10-days window" as described in the OECD guideline 301B was not regarded because the test item is a mixture of different reaction products and not a pure substance. Thus the test item is regarded as readily biodegradable.
The mean degradation value of the test item was 75%.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1989-07 - 1989-08
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Qualifier:
according to guideline
Guideline:
EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test)
GLP compliance:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): Amides, coco, N-[3-(dimethylamino)propyl], N-oxides
- Substance type: amide
- Physical state: liquid, faint yellowish
- Storage condition of test material: test substance stored at room temperature
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): inoculum collected from the clarifier effluent of a municipal waste water treatment plant (waste water treatment plant located at Bergisch Gladbach/Refrath, Germany)
- Laboratory culture: no
- Storage conditions: not reported
- Preparation of inoculum for exposure: Inoculum was filtered through a coarse filter paper, the first 200 ml were discarded; 0.5 mL of inoculum were used in the test.
- Pretreatment: not reported
- Concentration of sludge: not applicable
- Water filtered: not reported
Duration of test (contact time):
28 d
Initial conc.:
24.6 mg/L
Based on:
DOC
Initial conc.:
25.4 mg/L
Based on:
DOC
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium (not further specified)
- Additional substrate: not reported
- Solubilising agent (type and concentration if used): not necessary as the test item was well soluble in water
- Test temperature: not reported
- pH: not reported
- pH adjusted: not reported
- Aeration of dilution water: not reported
- Continuous darkness: not reported

TEST SYSTEM
- Culturing apparatus: not reported
- Number of culture flasks/concentration: 2 each (test conducted with 24.6 and 25.4 mg DOC/L)
- Method used to create aerobic conditions: not reported
- Measuring equipment: Shimadzu TOC-500 analyzer
- Test performed in closed vessels due to significant volatility of test substance: not reported

SAMPLING
- Sampling frequency: sampling/measurement was carried out on day 0 and after 6, 14, 21, 27, and 28 days

CONTROL AND BLANK SYSTEM
- Inoculum blank: performed
- Abiotic sterile control: not reported
- Toxicity control: not reported
Reference substance:
acetic acid, sodium salt
Test performance:
The study was conducted according to EU Method C.4-B (Determination of the "Ready" Biodegradability - Modified OECD Screening Test, 1984) and similar to OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test).
Key result
Parameter:
% degradation (DOC removal)
Value:
66
Sampling time:
28 d
Remarks on result:
other: the pass level (70%) was not reached within the test period, therefore the test item can be regarded as not readily biodegradable
Details on results:
Biodegradation rates of the test substance

% DOC/L after x days
0 6 14 21 27 28
Test 1* 0 63 63 63 68 68
Test 2* 0 64 62 62 62 66
mean 0 63 63 63 66 67
The test item proved to be not readily biodegradablethe as the pass level (70%) was not reached within the test period.
Results with reference substance:
The following results were obtained with the reference substance sodium acetate (concentrations tested: 29.7 and 30.3 mg DOC/L)
day 0: 0%
days 6: 91-92%
days 14: 100%
days 21: 100%
days 27: 100%
days 28: 100%

In a study conducted according to EU method C.4 -B (determination of the "Ready Biodegradability - Modified OECD Screening Test, 1984) and similar to OECD Guideline 301 E (Ready biodegradability. Modified OECD Screening Test) the following results were obtained:

a. results of the DOC measurements

mg DOC/L after x days

0

6

14

21

27

28

Test 1*

1

2

mean

26.1

24.7

25.4

10.8

11.4

11.1

8.7

8.7

8.7

8.6

8.6

8.6

8.6

8.5

8.6

7.1

7.9

7.5

Test 2*

1

2

mean

24.7

24.6

24.7

10.9

10.2

10.6

8.7

8.7

8.7

8.6

8.6

8.6

8.5

8.7

8.6

7.4

8.0

7.7

Inoculum blank

1

2

mean

1.9

1.9

1.9

2.6

2.4

2.5

0

0

0

0

0

0

0

0

0

0

0

0

* concentrations of the test substance : 24.6 and 25.4 mg/L

b. biodegradation rates

% DOC/L after x days

0

6

14

21

27

28

Test 1*

0

63

63

63

68

68

Test 2*

0

64

62

62

62

66

mean

0

63

63

63

66

67

The test item proved to be not readily biodegradable at the pass level (70%) was not reached within the test period

Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
The test item proved to be not readily biodegradable as the pass level (70%) was not reached within the test period (biodegradation after 28 d: 67%).
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2000-08-09 - 2000-09-06
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Name (as cited in study report): N-(3-N,N-dimetylainooxidetrimetylene)alkylamide
- Code name: NINOX HCDO
- Purity: 92%
- Lot/batch no.: 876 TK Sample IX
- Expiration date of the lot/batch: not stated
- Stability under test conditions: the confirmation of the stability in the test conditions is unnecessary, because the study is for estimation of biodegradation
- Storage conditions of test material: dark place at room temperature
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): the standard activated sludge was purchased from Chemicals and Research Institute Japan on July 9, 2000
- Laboratory culture: the AS was cultured under the conditions of 25±2.0°C, 5 mg/L of DO concentration and pH 7.0± 1 at the test facility
- Initial cell/biomass concentration: 2601 mg/L
Duration of test (contact time):
28 d
Initial conc.:
ca. 100 mg/L
Based on:
other: Total organic carbon (TOC)
Parameter followed for biodegradation estimation:
TOC removal
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: standard activated sludge purchased from Chemicals Evaluation and Research Institute Japan, on July 2000
- Additional substrate: no
- Solubilising agent (type and concentration if used): no
- Test temperature: 24.9 - 25.0 ºC
- pH: 7.0 ± 1.0
- pH adjusted: no
- CEC (meq/100 g):
- Aeration of dilution water:
- Suspended solids concentration: 2601 mg/L
- Continuous darkness: yes/no
- Other: volume of test solution was 300 mL, test water was prepared by MILLI-Q (Japan Millipore Ltd.)

STATISTICAL METHODS:
- values of TOC were calculated by a data processor belonging to TOC analyzer
Reference substance:
aniline
Remarks:
(for the biodegradability test)
Key result
Parameter:
% degradation (TOC removal)
Value:
98
Sampling time:
28 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
85
Sampling time:
28 d
Results with reference substance:
The percentage degradation obtained with the reference substance was 58% after 7 day of exposure.
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test substance is considered as readily biodegradable after 28 days with a biodegradation percentage of 85%.
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2004-12-02 - 2004-12-31
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): Aminoxid WS 35
- Identifiers: EC268-938-5, CAS68155-09-9
- Substance type: fatty acid amidoalkyldimethylaminoxide
- Physical state: not reported (provided as aqueous solution)
- Analytical purity: 35% active ingredient
- Impurities (identity and concentrations): not stated
- Composition of test material, percentage of components: aqueous solution of test item
- Purity test date: 23.11.2004
- Lot/batch No.: PA14900085
- Expiration date of the lot/batch: 2005-11-19
- Stability under test conditions: not reported
- Storage condition of test material: the test item was stored at room temperature, protected from moisture and light
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): activated sludge sampled from municipal sewage treatment plant (Hildesheim, Germany) which treated mostly municipal sewage and hardly industrial chemical waste
- Preparation of inoculum for exposure: the activated sludge was maintained in aerobic condition by aeration for four hours and was then homogenized with a mixer; the sludge was filtered and the filtrate (30 mL) was subsequently used for inoculation
- Pretreatment: no
- Concentration of sludge: 30 mL
- Initial cell/biomass concentration: 10E5-10E6 CFU/L in the test vessels
- Water filtered: not reported
Duration of test (contact time):
28 d
Initial conc.:
45 mg/L
Based on:
test mat.
Initial conc.:
11.7 mg/L
Based on:
other: carbon content in test vessel
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral nutrient solution acc. to OECD guideline 301B
- Additional substrate: not reported
- Solubilising agent (type and concentration if used): no
- Test temperature: 20-24°C
- pH: initial pH not reported; at the end of the study the pH was measured in all bottles: 7.51-7.59 (control), 7.86 (functional control), 7.59 (test item), and 7.96 (toxicity control)
- pH adjusted: not reported
- Aeration of dilution water: not reported
- Suspended solids concentration: filtrate of activated sludge was used as inoculum (30 mL), 10E5-10E6 CFU/L in the test vessels
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: brown glass bottles
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: aeration
- Measuring equipment: pH-Meter, Multilab 340i, WTW, Thermohygrograph, type 3.015/3 K, fabr.-no. 9003146, Thermohygrograph, LUFFT, Flow meter, KROHNE DUISBURG TYP DK 800 PV
- Test performed in closed vessels: yes
- Details of trap for CO2 and volatile organics if used: after aeration of the test vessels with CO2 free air for 24 h the CO2 adsorption vessels were connected to the air outlets of the incubation vessels via a series of 3 gas wash bottles containing Ba(OH)2

SAMPLING
- Sampling frequency: CO2 production was determined on day 1,4,6,8,11,14,18,21,25,28,and 29* (*last two gas wash bottles)
- Sampling method: CO2 was determined in the adsorption units

CONTROL AND BLANK SYSTEM
- Inoculum blank: performed
- Toxicity control: performed
- Other: functional control (reference substance) performed
Reference substance:
acetic acid, sodium salt
Test performance:
The study was conducted according to OECD Guideline 301B 'CO2 evolution test'.
Key result
Parameter:
% degradation (CO2 evolution)
Value:
68
Sampling time:
28 d
Results with reference substance:
Results with the reference substance sodium acetate
study day biodegradation (%)
day 1: 8
day 8: 55
day 14: 68
day 21: 74
day 28: 82

In a study conducted according to OECD Guideline 301 B 'Ready Biodegradability: CO2 Evolution Test' the following results were obtained:


a. CO2 production and biodegradation in the control and test item samples





































































































































Study day



Control (mg CO2/3L); mean value



Test item (45 mg/L; 11.7 mg C/L)



Replicate 1



Replicate 2



Gross (mg CO2/3L)



Net (mg CO2/3L)



Degradation (%)



Gross (mg CO2/3L)



Net (mg CO2/3L)



Degradation (%)



1



4.0



3.2



-0.8



0



2.9



-1.1



0



4



21.4



17.7



-3.7



0



28.3



6.9



5



6



35.3



50.9



15.6



12



53.4



18.1



14



8



48.4



79.4



31.0



24



78.4



30.0



23



11



62.1



108.1



46.0



35



108.7



46.6



36



14



79.0



134.2



55.2



43



135.7



56.7



44



18



99.9



163.7



63.8



49



161.2



61.3



47



21



119.3



190.5



71.2



55



186.4



67.1



52



25



139.6



220.4



80.8



62



214.3



74.7



58



28



154.8



245.0



90.2



70



241.7



86.9



67



29*



168.1



260.6



92.5



71



256.3



88.2



68



*results of the last two gas wash bottles determined on day 29 (after 28 days the aeration was continued for further 24 h and the quantity of CO2 released in the last two gas wash bottles was measured)


 


Based on the results, the test item can be regarded as readily biodegradable. The "10-day window" was not met (the 10% level was reached after 6 days and the pass level of 60% on day 25), however this criteria is not considered further as the substance is a UVCB.


 


In the control a gross CO2 production of 168.1 mg CO2/3L (=56.0 mg CO2/L) was measured. According to guideline the CO2 evolution in the control should not normally exceed 40 mg/L, but values up to 70 mg/L were acceptable.


 


b. CO2 production and biodegradation in the control, functional control and toxicity control samples




































































































































 



 



Functional control (35 mg/L)



Toxicity control (35 mg/L reference item and 45 mg/L test item)



Study day



Control (mg CO2/3L); mean value



Gross (mg CO2/3L)



Net (mg CO2/3L)



Degradation (%)



Gross (mg CO2/3L)



Net (mg CO2/3L)



Degradation (%)



1



4.0



13.4



9.4



8



3.9



-0.1



0



4



21.4



54.1



32.7



29



58.5



37.1



15



6



35.3



88.1



52.8



47



113.0



77.7



32



8



48.4



109.9



61.5



55



154.6



106.2



44



11



62.1



133.7



71.6



64



187.5



125.4



52



14



79.0



155.3



76.3



68



215.7



136.7



56



18



99.9



179.2



79.3



71



244.7



144.8



60



21



119.3



202.1



82.8



74



264.5



145.2



60



25



139.6



228.0



88.4



79



292.9



153.3



63



28



154.8



247.1



92.3



82



315.7



160.9



67



29*



168.1



269.2



101.1



90



345.4



177.3



73



Based on the results of toxicity testing, it can be concluded that the test item was not inhibitory to the inoculum (>35% biodegradation after 14 d).

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
In a study conducted according to OECD Guideline 301 B 'Ready Biodegradability: CO2 Evolution Test' the test item proved to be readily biodegradable, with the two replicates attaining 68% and 71% degradation respectively after 29 days.
The test substance did not meet the "10-day window" criterion (the 10% level was reached after 6 days and the pass level of 60% on day 25). However, this 10-day window is not applicable as the substance is a UVCB mixture of structurally similar chemicals. As the substance exhibited the potential for rapid degradation and the 60% pass level was met on day 25, the substance is regarded as readily biodegradable.

Description of key information

The study of Noack (2005) is selected as key study and used to conclude on the ready biodegradability of the substance in an aerobic aqueous medium. The study is given a Klimisch score of 1 and was conducted under GLP. The study is carried out according to OECD guideline 301B (CO2 evolution test). The test item is regarded as readily biodegradable, with the two replicates attaining 68% and 71% degradation respectively after 29 days. The test substance did not meet the "10-day window" criterion (the 10% level was reached after 6 days and the pass level of 60% on day 25). However, this 10-day window is not applicable as the substance is a UVCB mixture of structurally similar chemicals. As indicated in the Guidance on Information Requirements and Chemical Safety Assessment R.7b (2017) and in the OECD Guidelines for the Testing of Chemicals, Revised Introduction To The OECD Guidelines For Testing Of Chemicals, Section 3 Part I: Principles And Strategies Related To The Testing Of Degradation Of Organic Chemicals (OECD, 2006b), the 10-day window does not apply in cases where the substance is made of a composition of homologous constituents. Because the substance exhibited the potential for rapid degradation and the 60% pass level was met on day 25, the substance is regarded as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

Four additional studies are included as supporting information on the ready biodegradability of the substance.


 


The study of Lebertz (2005) was carried out according to the OECD guideline 301B (CO2 evolution test). The study reported a mean degradation value of the test item of 75% after 28 days. As discussed for the key study, the "10-day window" criteria was not regarded and the test item was concluded to be readily biodegradable. The study was conducted under GLP and is given a Klimisch score of 1.


 


The GLP study of Ishihara (2000) was carried out according to the OECD guideline 301C (modified MITI study) and is assigned a Klimisch score of 2. The substance showed 85% degradation after 28 days and is concluded to be readily biodegradable.


 


The non-GLP study of Wörmann (1989) was assigned a Klimisch score of 2 and is selected as supporting study. The study is conducted according to EU method C.4 -B and similar to OECD Guideline 301E. The test substance proved to be not readily biodegradable as the pass level of 70% was not reached within the test period (biodegradation after 28 d: 66%).


 


The GLP study of Brunswik-Titze (2015) investigates the anaerobic biodegradation of the substance according to the OECD guideline 311. The biodegradation of the substance was 61% within 61 days. The study is assigned a Klimisch score of 1 and is used as a supporting study providing additional information on the biodegradability of the substance in anaerobic conditions.