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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:
key study
Study period:
08 June 2017 - 24 August 2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Version / remarks:
23 March 2006
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: municipal sewage treatment plant: 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands,
- Storage conditions: not applicable, the freshly obtained sludge was used immediately.
- Preparation of inoculum for exposure: before use, the sludge was allowed to settle (40 minutes) and the liquid was decanted for use as inoculum at the amount of 10 mL/L of mineral medium.
- Concentration of sludge: 3.2 g suspended solids/L
Duration of test (contact time):
28 d
Initial conc.:
3.5 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
TOC
Initial conc.:
0.62 other: mg/mg
Based on:
ThIC
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
TEST CONDITIONS
- Composition of medium: mineral medium according to OECD guideline 310
- Test temperature: 19.7 and 24.1°C
- pH: 7.8 for the test item vessels (7.5-7.9 for controls)
- pH adjusted: no
- Aeration of dilution water: not indicated
- Suspended solids concentration: sludge liquid at an amount of 10 mL/L mineral medium (concentration of suspended solids not indicated)
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: well sealed glass serum vessels.
- Number of culture flasks/concentration: five test vessels for analysis at the end of the test and three test vessels for other time intervals for the test item and each of the control treatments.
- Method used to create aerobic conditions: not indicated
- Measuring equipment: Shimadzu TOC-VCPH total organic carbon analyser combined with a Shimadzu ASI-V autosampler
* Calibration solution: IC standard: sodium hydrogen carbonate/sodium carbonate solution
- Other: incubation was peformed in an orbital shaker, with a shaking rate sufficient to keep the vessel well mixed and in suspension.

SAMPLING
- Sample pretreatment: 1 mL 7 M NaOH was injected through the septum of each vessel and the vessels were returned to the orbital shaker for 1 h. Thereafter, the vessels were removed from the shaker and allowed to settle. The supernatant was used for IC analysis.
- Sampling frequency:
*inoculum blank and test item: day 1, 7, 14, 21 and 28
*procedure control and toxicity control: day 1, 7 and 14
*abiotic control: day 1 and 28

DETERMINATION OF BIODEGRADATION:
The CO2 evolution resulting from the aerobic biodegradation of the test item was determined by determining the inorganic carbon (IC) produced in the test item vessels in excess of that produced in the inoculum blank. Biodegradation was expressed as a percentage of the ThIC, based on the quantity of test item (as C) initially added.

CONTROL AND BLANK SYSTEM
- Inoculum blank: containing inoculated medium
- Abiotic sterile control: containing untreated medium, test item and 1 mL of a solution containing 10 g/L of HgCl2 as sterilising agent
- Toxicity control: containing inoculated medium, reference item and test item
- Procedure control: containing inoculated medium and reference item

Reference substance:
other: octan-1-ol
Remarks:
purity: 98%; ThIC: 0.74 mg/mg
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
3
Sampling time:
28 d
Details on results:
- The value for biodegradation of the test item was corrected for degradation in the abiotic control (13%).
- In the toxicity control more than 25% biodegradation occurred within 14 days (45%, based on ThIC). Therefore, the test item was assumed not to inhibit microbial activity.
Results with reference substance:
The reference item biodegraded for 105% after 14 days, indicating that the test system functioned properly.

Table 1 Biodegradation in Percentage of theTheoretical maximum IC Production (ThIC)

Nominal day

Microbial degradation in percentage of the ThIC

Degradation

Reference Item

Test Item

Toxicity Control

Abiotic Control

1

0

14

1

12

7

83

13

48

-

14

105

16

45

-

21

-

18

-

-

28

-

16

-

13

- = Not measured

Validity criteria fulfilled:
yes
Remarks:
see 'Overall remarks'
Interpretation of results:
not readily biodegradable
Conclusions:
Under the conditions of the Headspace Test, performed according to OECD guideline 310 and GLP conditions, FORTIMOTM 1,4-H6XDI was not readily biodegradable.
Executive summary:

A Headspace Test was performed according to OECD guideline 310 and GLP principles, to assess the ready biodegradability of FORTIMOTM 1,4-H6XDI. Activated sludge was exposed to the test item at a concentration of 3.5 mg/L, corresponding to a organic carbon content of 20 mg/L, for 28 days. Octan-1 -ol was tested as reference substance (procedure control) and a blank control, abiotic control and toxicity control were included. Analysis of test item samples was performed at day 1, 7, 14, 21 and 28. Five replicates were used for the analysis at the end of the test and three replicates for analysis at other time intervals. The percentage biodegradation was determined by the amount of inorganic carbon produced in excess of the amount produced in the inoculum blank. Biodegradation was expressed as a percentage of the theoretical inorganic carbon (ThIC) based on the quantity of test item initially added. The ThIC of the test item was determined to be 0.62 mg/mg. At the end of the exposure period, the test item showed 3% biodegradation (corrected for degradation by the abiotic control (13%)) and thus the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. Since the reference item was biodegraded for 105% and the mean amount of ThIC present in the inoculum blanks at the end of the test was 2 mg/L, the test system was shown to function properly and the acceptability criteria were met. Also, based on the results of the toxicity control, the test item was found not to inhibit microbial activity. Under the conditions of this test, FORTIMO(TM) 1,4-H6XDI was not readily biodegradable.

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:
The rationale to read across the data is attached in Section 13.
Reason / purpose:
read-across source
GLP compliance:
yes
Duration of test (contact time):
d
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
3
Sampling time:
28 d
Details on results:
- The value for biodegradation of the test item was corrected for degradation in the abiotic control (13%).
- In the toxicity control more than 25% biodegradation occurred within 14 days (45%, based on ThIC). Therefore, the test item was assumed not to inhibit microbial activity.
Results with reference substance:
The reference item biodegraded for 105% after 14 days, indicating that the test system functioned properly.

Table 1 Biodegradation in Percentage of theTheoretical maximum IC Production (ThIC)

Nominal day

Microbial degradation in percentage of the ThIC

Degradation

Reference Item

Test Item

Toxicity Control

Abiotic Control

1

0

14

1

12

7

83

13

48

-

14

105

16

45

-

21

-

18

-

-

28

-

16

-

13

- = Not measured

Validity criteria fulfilled:
yes
Remarks:
see 'Overall remarks'
Interpretation of results:
not readily biodegradable
Conclusions:
Under the conditions of the Headspace Test, performed according to OECD guideline 310 and GLP conditions, FORTIMOTM 1,4-H6XDI was not readily biodegradable. This result is read across to 1,3-H6XDI.
Executive summary:

A Headspace Test was performed according to OECD guideline 310 and GLP principles, to assess the ready biodegradability of FORTIMOTM 1,4-H6XDI. Activated sludge was exposed to the test item at a concentration of 3.5 mg/L, corresponding to a organic carbon content of 20 mg/L, for 28 days. Octan-1 -ol was tested as reference substance (procedure control) and a blank control, abiotic control and toxicity control were included. Analysis of test item samples was performed at day 1, 7, 14, 21 and 28. Five replicates were used for the analysis at the end of the test and three replicates for analysis at other time intervals. The percentage biodegradation was determined by the amount of inorganic carbon produced in excess of the amount produced in the inoculum blank. Biodegradation was expressed as a percentage of the theoretical inorganic carbon (ThIC) based on the quantity of test item initially added. The ThIC of the test item was determined to be 0.62 mg/mg. At the end of the exposure period, the test item showed 3% biodegradation (corrected for degradation by the abiotic control (13%)) and thus the criterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. Since the reference item was biodegraded for 105% and the mean amount of ThIC present in the inoculum blanks at the end of the test was 2 mg/L, the test system was shown to function properly and the acceptability criteria were met. Also, based on the results of the toxicity control, the test item was found not to inhibit microbial activity. Under the conditions of this test, FORTIMO(TM) 1,4-H6XDI was not readily biodegradable. This result is read across to 1,3-H6XDI.

Description of key information

Under the conditions of the Headspace Test, performed according to OECD guideline 310 and GLP conditions, 1,4-H6XDI was not readily biodegradable. This result is read across to 1,3-H6XDI.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed
Type of water:
freshwater

Additional information

A Headspace Test was performed according to OECD guideline 310 and GLP principles, to assess the ready biodegradability of 1,4-H6XDI. Activated sludge was exposed to the test item at a concentration of 3.5 mg/L, corresponding to a organic carbon content of 20 mg/L, for 28 days. Octan-1 -ol was tested as reference substance (procedure control) and a blank control, abiotic control and toxicity control were included. Analysis of test item samples was performed at day 1, 7, 14, 21 and 28. Five replicates were used for the analysis at the end of the test and three replicates for analysis at other time intervals. The percentage biodegradation was determined by the amount of inorganic carbon produced in excess of the amount produced in the inoculum blank. Biodegradation was expressed as a percentage of the theoretical inorganic carbon (ThIC) based on the quantity of test item initially added. The ThIC of the test item was determined to be 0.62 mg/mg. At the end of the exposure period, the test item showed 3% biodegradation (corrected for degradation by the abiotic control (13%)) and thus thecriterion for ready biodegradability (at least 60% biodegradation within a 10-day window) was not met. Since the reference item was biodegraded for 105% and the mean amount of ThIC present in the inoculum blanks at the end of the test was 2 mg/L, the test system was shown to function properly and the acceptability criteria were met. Also, based on the results of the toxicity control, the test item was found not to inhibit microbial activity. Under the conditions of this test, FORTIMO(TM) 1,4-H6XDI was not readily biodegradable. This result is read across to 1,3-H6XDI.