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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Administrative data

Endpoint:
biodegradation in water: sediment simulation testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
Although data provided have a report year after 2008, the data was obtained from a journal article which does not provide GLP information.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2013

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)
Deviations:
no
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Purity: > 97%
Radiolabelling:
yes

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
natural water / sediment
Details on source and properties of surface water:
The river water was collected from Brandywine Creek, PA at the position of Latitude 39 51 min 34 s, longitude 75 35 min 55 s, and 78 m above sea level.
Details on source and properties of sediment:
The river sediment was collected from Brandywine Creek, PA at the position of Latitude 39° 51 min 34 s, longitude 75° 35 min 55 s, and 78 m above sea level. The cobblestones and decayed leaves were discarded from the sediment after bringing the sediment to the laboratory. The sediment physicochemical characteristics were determined. The collected sediment was sandy loam (67% sand, 24% silt, and 9% clay) with 5.3% organic matter or 3.1% organic carbon content. The pH of the sediment was 6.9 and the cation exchange capacity (CEC) was 86 mmol/kg sediment.
Details on inoculum:
- Source of inoculum/activated sludge: organisms native to the water and sediment
- Preparation of inoculum for exposure: incubated at room temperature for 5 days before dosing
Duration of test (contact time):
100 d
Initial test substance concentration
Initial conc.:
50 other: µg/bottle
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Details on study design:
TEST CONDITIONS
- Volume of test solution/treatment: 50 µg/bottle
- Composition of medium: 5 mL mineral media - 85 mg/L of KH2PO4, 218 mg/L of K2HPO4, 334 mg/L of Na2HPO4•2H2O, 5 mg/L of NH4Cl, 36.4 mg/L of CaCl2•2H2O, 22.5 mg/L of MgSO4•7H2O, and 0.25 mg mg/L of FeCl3•6H2O with a pH of 7.0.
- Test temperature: room temperature

TEST SYSTEM
- Culturing apparatus: 119-mL glass serum bottles
- Number of culture flasks/concentration: 3 live, 3 sterile control, and 2 live matrix control bottles for each sampling time
- Method used to create aerobic conditions: two SPE cartridges enabled air exchange between headspace and ambient air and also captured
volatiles during biotransformation.

SAMPLING
- Sampling frequency: days 0, 2, 7, 14, 28, 56, and 100
- Sampling method: extract entire contents including septa and SPE cartridges

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes

Results and discussion

Mean total recoveryopen allclose all
Compartment:
other: water, material (mass) balance
% Recovery:
16
Compartment:
other: sediment, material (mass) balance
% Recovery:
39
% Degradation
% Degr.:
>= 93.9 - <= 96.1
Parameter:
test mat. analysis
Sampling time:
28 d
Remarks on result:
other: Primary degradation
Half-life of parent compound / 50% disappearance time (DT50)
Compartment:
entire system
DT50:
1.8 d
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: Mass balance at day 100: 16% in water, 39% in sediment, 15% in headspace
Transformation products:
yes
Identity of transformation productsopen allclose all
Evaporation of parent compound:
yes
Volatile metabolites:
yes
Residues:
yes
Details on results:
TEST CONDITIONS
- Aerobicity (or anaerobicity), moisture, temperature and other experimental conditions maintained throughout the study: Yes

Any other information on results incl. tables

5:3 Acid is a predominant product during the test substance aerobic biotransformation in river sediment. PFPeA, PFHxA, and PFBA also are formed during the test substance biotransformation in river sediment. 5:3 Acid was sediment-bound and can only be recovered by post-treatment with NaOH and ENVI-Carb™. The 5:3 acid can be further degraded to 4:3 acid in river sediment via one-carbon removal pathways.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
The test substance biotransformation was rapid (T1/2 < 2 days). By day 28 primary degradation was 93.9 to 96.1%
Executive summary:

A novel aerobic sediment experimental system containing 20 g wet sediment and 30 mL aqueous solution was developed to study biotransformation in river sediment. The test substance was dosed into the sediment to follow its biotransformation and to analyse transformation products over 100 days.

 

The test substance biotransformation was rapid, half-life was 1.8 days. By day 28 primary degradation was 93.9 to 96.1%. 5:3 Acid is a predominant product during the test substance aerobic biotransformation in river sediment. PFPeA, PFHxA, and PFBA also were formed during the test in river sediment. 5:3 Acid was sediment-bound and can only be recovered by post-treatment with NaOH and ENVI-Carb™. The 5:3 acid can be further degraded to 4:3 acid in river sediment via one-carbon removal pathways.