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Environmental fate & pathways

Biodegradation in water: screening tests

Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
6 Mar - 5 Apr 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Physical state: viscous colorless liquid at room temperature (22-23 °C)
- Source and lot/batch No.of test material: Lot 10115
- Expiration date of the lot/batch: 10 Jan 2019
- Purity: 95.6%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: frozen

FORM AS APPLIED IN THE TEST: solid

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of activated sludge: Easton Wastewater Treatment Facility, Easton, Maryland on March 05, 2018, receiving predominantly residential wastes
- Preparation of inoculum for exposure: The sludge was sieved using a 2-mm screen, adjusted to approximately 1000 mg total suspended solids/L with mineral media and then aerated at test temperature until use.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
10 mg/L
Based on:
TOC
Parameter followed for biodegradation estimation
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium (per liter):
1 mL calcium chloride solution (2.75%)
1 mL of ferric chloride solution (0.025%)
1 mL of magnesium sulfate solution (2.25%)
10 mL of phosphate buffer (pH 7.4)
- Test temperature: 19.15-21.69 ºC
- pH: 7.48 - 7.60
- pH adjusted: no
- Suspended solids concentration: ≤ 30 mg/L

TEST SYSTEM
- Culturing apparatus: Amber 4-L bottles, 3-L fill volume. The air entering the chambers was passed through Drierite™ to remove ambient moisture and then through Ascarite® to produce CO2-free air.
- Number of culture flasks/concentration: 3
- Details of trap for CO2 and volatile organics if used: The air exiting the test chambers was passed through a series of three gas washing bottles, each containing approximately 100 mL of 0.5 M potassium hydroxide (KOH) to trap the CO2 that had evolved within the chamber. On sampling days, the CO2 trap nearest the test chamber was collected for analysis of inorganic carbon. The two remaining traps were placed one position closer to the test chamber and a new trap was placed on the end of the series.

SAMPLING
- Sampling frequency: On days 2, 5, 8, 12, 15, 18, 22, and 26

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: yes
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Key result
Parameter:
% degradation (CO2 evolution)
Value:
17.9
Sampling time:
28 d
Details on results:
The toxicity control achieved > 25% degradation by Day 14 (62.9%) and therefore MTDID 10628 may be considered non-inhibitory at the concentration tested in this study. The amount of CO2 evolved by the blank control chambers (24.3 mg/L) did not exceed the 40 mg/L value considered the acceptable limit for CO2 evolution tests.

BOD5 / COD results

Results with reference substance:
An average of 104.3% of theoretical CO2 was evolved over the test period; an average biodegradation greater than 60% was achieved by Day 5.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
reference >60% degraded by day 14, difference in test substance degradation between chambers <20%, total CO2 in blanks <40 mg/L (24.3 mg/L)
Interpretation of results:
not readily biodegradable
Conclusions:
1,1'-Isophthaloylbis(2-methylaziridine) was degraded 17.9% in an OECD 301B test. 1,1'-Isophthaloylbis(2-methylaziridine) was not inhibitory to biodegradation.
Executive summary:

The degradability of 1,1'-isophthaloylbis(2-methylaziridine) was assessed according to OECD 301B. The test contained a blank control group, a reference group (sodium benzoate), and a treatment group, each with three replicates and a single toxicity control. the reference substance was degraded adequately by day 5. The average cumulative percent biodegradation for 1,1'-isophthaloylbis(2-methylaziridine) was 17.9% by the end of the 28-day test. The toxicity control was biodegraded 62.9% in the same time period. The test substance is not readily biodegradable but is not inhibitory to biodegradation.

The test was conducted according to internationally accepted guidelines under GLP criteria. It is considered reliable without restrictions and is suitable for Risk Assessment, Classification & Labelling, and PBT Analysis.