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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016-07-07 to 2016-08-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Qualifier:
according to
Guideline:
EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)
Deviations:
no
Qualifier:
according to
Guideline:
ISO 10707 Water quality - Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds - Method by analysis of biochemical oxygen demand (closed bottle test)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Batch n°: A15JB2997
- Analytical purity: 97.5% (GC)
- Expiration date: 2016-10-21 (re-test date)

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition: at room temperature
- Stability under storage conditions: until retest date
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source: municipal sewage treatment plant receiving predominantly domestic sewage, 'Waterschap Aa en Maas', 's-Hertogenbosch, The Netherlands.
- Treatment: Secondary effluent was filtered through a coarse filter paper, the first 200 mL was discarded. The filtrate was kept aerated until inoculation.
- Inoculation: 4 mL filtrate of secondary effluent per litre of final volume.

Duration of test (contact time):
28 d
Initial conc.:
1 mg/L
Based on:
test mat.
Initial conc.:
3 mg/L
Based on:
test mat.
Initial conc.:
2.31 other: mg O2/mg
Based on:
ThOD
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: test water prepared according to test guidelines, analytical grade salts dissolved in tap-water purified by reverse osmosis (Milli-RO).
* mineral stock solution A: 8.5 g KH2PO4, 21.75 g K2HPO4, 67.20 g Na2HPO4.12H2O, 0.5 gNH4Cl dissolved in 1 L Milli-Q water, pH 7.4 ± 0.2
* mineral stock solution B: 22.50 g MgSO4.7H2O dissolved in 1 L Milli-Q water
* mineral stock solution C: 36.4 g CaCl2.2H2O dissolved in 1 L Milli-Q water
* mineral stock solution D: 0.25 g FeCl3.6H2O dissolved in 1 L Milli-Q water
* Final test medium: 1 mL of solution A, B, C and D was mixed and made up to 1 L with Milli-RO water
- The concentration of dissolved oxygen was measured for control purposes. The mineral medium was left at test temperature to obtain a saturated solution at the start of the test.
- Additional substrate: no
- Test temperature: 22-23°C (measured continuously in a vessel with Milli-RO water in the same room)
- pH: 7.2-7.4, measured at the start of the test
- pH adjusted: no data
- Aeration of dilution water: Dissolution of the test item was accelerated by magnetic stirring (approximately 3 hours).
- Continuous darkness: yes

TEST SYSTEM
- Test bottles: 250-300 mL BOD bottles with glass stoppers
- Test setup:
* test substance and inoculum
* inoculum blank
* positive control/procedure control
* toxicity control
Individual BOD bottles were prepared for each measuring point, except that the bottles measured at the start were also measured on day 7. Parallel groups were prepared to allow duplicate measurements of oxygen consumption at the test intervals.
- Measuring equipment: measurement of oxygen concentration (WTW oxygen meter supplied with a WTW CellOx 325 oxygen electrode, electrolyte type ELY/G)

SAMPLING
- Frequency: Oxygen concentration is determined in duplicate; immediately at the start of the experiment (day 0), and at day 7, 14, 21 and 28.
- pH was determined at the start of the test

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (only inoculum, no test item)
- Toxicity control: yes (test item, reference substance, and inoculum)
- Procedure control: yes (reference item and inoculum)
The test was performed in duplicate.

- test duration: 28 days for the inoculum blank and test suspension and 14 days for the procedure control and toxicity control
Reference substance:
acetic acid, sodium salt
Remarks:
sodium acetate
Test performance:
- In the toxicity control more than 25% biodegradation occurred within 14 days (68%, based on ThOD). Thus, the toxicity control showed that JNJ-118872-AAA (T000749) did not inhibit microbial activity.
- Sodium acetate (procedure control) was degraded by at least 60% (86%) within 14 days.
- Oxygen depletion in the inoculum blank was less than 1.5 mg O2/L after 28 days (0.6 mg O2/L).
- The residual concentration of oxygen in the test bottles was > 0.5 mg/L at any time.
- All differences of duplicate biodegradation values expressed as mg O2/L were less than 20% (1-7%).
Since all criteria for validity of the test were met, this study was considered to be valid.
Parameter:
% degradation (O2 consumption)
Value:
65
Sampling time:
28 d
Remarks on result:
other: 3 mg/L
Parameter:
% degradation (O2 consumption)
Value:
69
Sampling time:
28 d
Remarks on result:
other: 1 mg/L
Details on results:
More then 60 % of the test substance was degraded whithin 28 days at a test concentration of 3 mg/L. Since all criteria for validity of the test were met, this study was considered to be valid, the test substance can be regarded as readily biodegradable.
Results with reference substance:
procedure control was degraded by at least 60% (86%) within 14 days. The ThOD of sodium acetate (reference item) was calculated to be 0.78 mg O2/mg.
Validity criteria fulfilled:
yes
Remarks:
A different batch of the reference item was used in the test. The purity of the new batch was comparable to the batch stated in the study plan (i.e. 99.1% vs. 99.6%).The study integrity was not adversely affected by the deviation
Interpretation of results:
readily biodegradable
Conclusions:
The relative biodegradation values calculated from the O2 measurements performed during the test period of 28 days revealed significant biodegradation of JNJ-118872-AAA (T000749) at both concentrations, i.e. 69% and 65% for the low and high concentration respectively.
In the toxicity control more than 25% biodegradation occurred within 14 days (68%, based on ThOD). Thus, the toxicity control showed that JNJ-118872-AAA (T000749) did not inhibit microbial activity.
JNJ-118872-AAA (T000749) was determined to be readily biodegradable under the conditions of the closed bottle test presently performed.

Description of key information

The K1 study (Desmares-Koopmans 2016), where the relative biodegradation values were calculated from the O2 measurements performed during the test period of 28 days, revealed significant biodegradation of the test item, i.e. 69% and 65% for the low and high concentration respectively. Additionally, the toxicity control showed that the test item did not inhibit microbial activity. Hence, it can be concluded that JNJ-118872-AAA (T000749) is readily biodegradable under the conditions of the closed bottle test presently performed.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information