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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:
1999-05-20 to 1999-06-18
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)
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): Jeffcat ZR-50
- Chemical name: 2-propanol, 1-(bis(3-(dimethylamino)propyl)amino)-
- Physical state: liquid
- Analytical purity: 100%
- Lot/batch No.: 184-3-0998
- Expiration date of the lot/batch: not provided
- Storage conditions: room temperature in the dark and dry
Oxygen conditions:
aerobic
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): secondary effluent from Thorndon Sewage Treatment Works, a trickling-filter plant that treats predominantly domestic waste; sample collected on the day of the test
- Storage conditions: maintained under aerobic conditions in the laboratory
- Storage length: < 24 h
- Pretreatment: vacuum-filtered through a Whatman GFC filter paper
- Filtrate used as inoculum
- Initial oncentration of sludge: 1 mL filtrate/L test medium.
Duration of test (contact time):
28 d
Initial conc.:
5 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Test temperature in the BOD bottles: 21.3-23.4°C
- pH: 7.0-8.2
- pH adjusted: yes (pH of stock solutions was adjusted to approximate neutrality before use)
- Aeration of dilution water: no
- Suspended solids concentration: not reported, 1 mL of filtrate was added per L of test medium
- Continuous darkness: yes

TEST SOLUTIONS
- Dilutions water: tap water, softened, treated by reverse osmosis, and then purified (resistivity >= 18 Megohm/cm)
- Composition of medium: Mineral Salts Medium
- Additional substrate: none
- Test substance was added as aqueous solution (0.5 g/L)

TEST SYSTEM
- Culturing apparatus: BOD bottles
- Number of culture flasks/concentration: 18 (single concentration)
- Measuring equipment: YSI dissolved oxygen meter fitted with a self­stirring DO/temperature bottle probe
- Test performed in closed vessels due to significant volatility of test substance: no

SAMPLING
- Sampling frequency: 5, 7, 11, 14, 18, 21, 25 and 28 days
- Duplicate vessels from each concentration were finished at each sampling occasion and used for DO, temperature and pH measurement.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (18 bottles)
- Positive control: yes, using sodium benzoate (5 mg/L) (18 bottles)
- Toxicity control: yes, using both the test substance and sodium benzoate at 5 mg/L (4 bottles, finished after 5 days of incubation)
Reference substance:
benzoic acid, sodium salt
Remarks:
5 mg/L
Preliminary study:
The ThOD (taking into account oxygen demand due to oxidation of N) was calculated to be 2.35 mg O2/mg.
Test performance:
- Sodium benzoate had been degraded to 57% of its ThOD after 5 d and achieved a max of 72% after 14 days.
- In the presence of the test substance, sodium benzoate had been degraded to 55% after 5 days.
- O2 consumption by day 28 in control bottles was acceptable (0.92 mg O2/L vs the recommended value of 1.5 mg O2/L).
- These results indicate that the inoculum was viable and that the test substance was not significantly inhibitory.
Parameter:
other: ThOD
Value:
2
Sampling time:
18 d
Remarks on result:
other: Maximum value
Details on results:
- Oxygen consumption in bottles containing Jeffcat ZR-50 alone was at most 0.04 mg 02/mg or 2% of its ThOD (Day 18).
- Jeffcat ZR-50 can therefore not be considered readily biodegradable.
Validity criteria fulfilled:
yes
Interpretation of results:
not readily biodegradable
Conclusions:
A 28-d closed bottle test showed a maximum removal of ThOD of the test substance of 2% (reached after 18 days). The activated sludge used was demonstrated to be viable, and the test substance was not significantly inhibitory at the concentration used in the test. Therefore, the test substance cannot be considered readily biodegradable.

Description of key information

A 28-d closed bottle test showed a maximum removal of ThOD of the test substance of 2% (reached after 18 days). The activated sludge used was demonstrated to be viable, and the test substance was not significantly inhibitory at the concentration used in the test. Therefore, the test substance cannot be considered readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information