Registration Dossier

Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

Currently viewing:

Administrative data

Endpoint:
biodegradation in water: sediment simulation testing
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Justification for type of information:
Category Approach; test material (C12 LAS) is major component of reference substance LAS. LAS
provides suitable read across for LAB Sulfonic Acids as both form the identical chemical species in
aqueous solutions at neutral (environmental) pH, namely, the LAS ion (C10-13linear alkyl benzene-
SO3-) and would be expected to have similar biodegradation properties.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2010
Report Date:
2010

Materials and methods

Test guidelineopen allclose all
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)
Deviations:
no
Qualifier:
equivalent or similar to
Guideline:
other: OECD 314
Deviations:
no
GLP compliance:
yes
Remarks:
The P&G Environ Science Lab is in the process of attaining formal GLP status. This expt was conducted in accordance with GLP's, by scientists with years of environ testing expertise. P&G helped develop and write the OECD protocol for this test method.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material: C12LAS; linear alkylbenzene sulfonate; (P&G Sample Code RC-99092-3). The test material was 14C-radiolabeled C12-alkylbenzene sulfonate (uniformly 14C-radiolabeled in ring).
- Substance type: pure active substance
- Physical state: solution in methanol
- Analytical purity: 91.2% active (by HPLC; %LAS)
- Impurities: 0.44% 2P2MC12 Quat (MLAS)
- Composition of test material: 91.2% C10-13-alkylbenzene sulfonate (average alkyl chainlength = 11.6). For details, see Table in "any other information on materials and methods" section below.
- Isomers composition: see Table below
- Purity test date: 4/7/1999
- Lot/batch No.: New England Nuclear lot # 3381-042
- Expiration date of the lot/batch: not available
- Radiochemical purity: >99% (determined by radio-TLC using silica gel plates and a mobile phase of chloroform/methanol/water/formic acid of 80/25/3/1).
- Specific activity: 9.71 mCi/mmol (dissolved in methanol, it was 3.59 mCi/ml)
- Locations of the label: Ring-14C(U)
- Expiration date of radiochemical substance: not provided
- Stability under test conditions: not provided
- Storage condition of test material: not provided
Radiolabelling:
yes

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
natural sediment
Details on source and properties of sediment:
Sediment was collected from Lytle Creek located in Wilmington, Ohio. Surficial (top 2-3 cm) sediment and overlying water was collected using a plastic scoop at a site immediately below the Wilmington Wastewater Treatment Plant outfall. The plant services a population of about 17,000 and receives about 90% of its waste from domestic sources. The sediment was placed in plastic jars and kept on ice during transport, and then stored in a 4 C cold room prior to the test. The sediment was characterized by the University of Wisconsin, Madison Soil & Plant Analysis Laboratory. The sediment type was sandy comprised of 95% sand, 2% silt, and 3% clay. Organic content was 2.1%, total nitrogen content was 0.02%, and pH was 7.9.
Details on inoculum:
Source of inoculum: see description of source and properties of sediment above
Duration of test (contact time):
148 d
Initial test substance concentration
Initial conc.:
1.5 other: mg/Kg dry weight
Based on:
act. ingr.
Parameter followed for biodegradation estimation:
CO2 evolution
test mat. analysis
other: Metabolites... (see attached file)
Details on study design:
OVERVIEW of EXPERIMENTAL DESIGN
The radiolabeled test substance was incubated with biotic and abiotic sediment samples under static conditions. The sediment for the abiotic treatment was autoclaved for 90 min and amended with mercuric chloride at 1 g/L to inhibit microbial activity. The test systems consisted of replicate 1 ml samples of sediment with 0.1 ml overlying water in test tubes, which were individually dosed with the test substance at a final added concentration of 4.1 mg/Kg dry weight.
Four replicate samples for the biotic treatment were prepared per sampling interval and all the biotic samples were incubated together in a sealed dessicator, which contained a 50 ml beaker containing 20 ml of 1.5 N KOH to trap any evolved 14CO2 in the headspace. In addition, the dessicator was continuously purged with CO2-free air to maintain aerobic conditions, and the effluent gas was passed through a gas trapping system consisting of one empty trap followed by three base traps containing 100 ml of 1.5 N KOH to recover any 14CO2 not collected by the internal trap. See the study report for diagrams of the test system and the analysis scheme.

TEST CONDITIONS
- Volume of test solution/treatment: 1 ml sediment with 0.1 ml overlying water
- Composition of medium: natural sediment, overlying water
- Additional substrate: no
- Solubilising agent: not used
- Test temperature: not specified in the study report
- pH: not specified in the study report
- pH adjusted: no
- Aeration of dilution water: N/A
- Suspended solids concentration: N/A
- Continuous darkness: not specified in the study report
- Any indication of the test material adsorbing to the walls of the test apparatus: no

TEST SYSTEM
- Culturing apparatus: test tubes
- Number of culture flasks/concentration: 4 at each time point
- Method used to create aerobic conditions: CO2-free air continuously pumped through test system
- Measuring equipment: see details on analytical methods
- Test performed in closed vessels: yes (CO2-free air purged through system to measure evolved 14CO2 in traps)
- Details of trap for CO2: see overview of experimental design above.

SAMPLING
- Sampling frequency: Biotic treament sampled after 15 min, and after 1, 2, 3, 6, 9, 14, 33, 92, and 148 days. The abiotic treatment was sampled less frequently.
- Sampling method: At each sampling, the dessicator was opened to change the internal base trap, and to recover sufficient samples for dissolved 14CO2, and for characterizing residual radioactivityf.
- Sample storage before analysis: not specified in study report

STATISTICAL METHODS: The parent loss and mineralization data were fit to a variety of first order decay and production equations using nonlinear regression. Regression analysis was performed using Jandel Table Curve 2D software (version 4.01).

Results and discussion

Mean total recovery
Compartment:
other: sediment, material (mass) balance
% Recovery:
101
St. dev.:
0.3
% Degradationopen allclose all
% Degr.:
60.8
St. dev.:
0.3
Parameter:
CO2 evolution
Sampling time:
148 d
Remarks on result:
other: Mean of biotic flasks; aerobic
% Degr.:
14.4
St. dev.:
0.7
Parameter:
other: associated with solids
Sampling time:
148 d
Remarks on result:
other: Mean of biotic flasks; aerobic
% Degr.:
1.4
St. dev.:
0.6
Parameter:
other: metabolites
Sampling time:
148 d
Remarks on result:
other: Mean of biotic flasks; aerobic
% Degr.:
24.5
St. dev.:
0.05
Parameter:
other: parent
Sampling time:
148 d
Remarks on result:
other: Mean of biotic flasks; aerobic
Half-life of parent compound / 50% disappearance time (DT50)open allclose all
Compartment:
sediment
DT50:
0.4 d
St. dev.:
0.1
Type:
other: two compartment first order model
Remarks on result:
other: Primary biodegradation; aerobic; compartment 1
Compartment:
sediment
DT50:
99 d
St. dev.:
4.2
Type:
other: two compartment first order model
Remarks on result:
other: Primary biodegradation; aerobic; compartment 2
Compartment:
sediment
DT50:
11.6 d
St. dev.:
1.5
Type:
other: first order
Remarks on result:
other: Mineralization; aerobic
Other kinetic parameters:
first order rate constant
Transformation products:
yes
Identity of transformation products
No.:
#1
Reference
Reference substance name:
Unnamed
IUPAC name:
unknown
Identifier:
other: Rf 0.57
Identity:
unknown
Details on transformation products:
Metabolites were not identified, other than by position on RAD-TLC:
Rf 0.36 parent
Rf 0.57 metabolite
Evaporation of parent compound:
no
Volatile metabolites:
not measured
Residues:
yes
Details on results:
Primary degradation was best described by a two compartment first order model (r2 > 0.99). The process was biphasic with two pools (compartments) of material exhibiting different degradation rates. Pool A (compartment 1) presumably was readily bioavailable test material, in the aqueous phase. Pool B (compartment 2) presumably was less bioavailable test material, bound to solids (sorbed).

Amount in pool A: 42.2%
Amount in pool B: 64.8%

Mineralization (14CO2 production) was best described by a First Order Model (r2 > 0.99), indicating that parent and metabolites were equally bioavailable to undergo mineralization.

Mass balance of abiotic flasks was 110.6% (107.5% parent, 3.0% associated with solids).

Any other information on results incl. tables

Fate of C12-LAS (C12-linear alkylbenzene sulfonate) in Aerobic Sediment: Die-Away Study using Lytle Creek Sediment (study 68316)

Time (days)

Parent (Rf 0.36)

Non-Polar Metabolite (Rf 0.57)

Solids

CO2

Total Recovery

0.01

108.6

1.4

4.0

Not sampled

113.2

1

72.9

5.7

22.9

10.4

108.9

2

69.5

0.0

20.3

20.2

110.0

3

60.9

1.3

23.9

18.8

104.9

6

61.8

4.0

22.8

19.4

106.0

9

64.5

1.7

19.8

21.5

106.7

14

56.7

1.9

18.9

31.9

108.4

33

39.5

1.0

18.6

46.5

105.4

61

26.7

0.7

16.9

53.5

97.8

148

24.5

1.4

14.4

60.8

101.0

 

 

 

 

 

 

Abiotic (n=5)

107.5

ND

3.0

Not analyzed

110.6

% of dosed radioactivity recovered as parent, metabolites, associated with extracted solids, or mineralized to CO2 as a function of time in Lytle Creek aerobic sediment.

Sediment dosed with [14C-U-ring] C12 linear alkylbenzene sulfonate.

Standard deviations are available in the study report.

ND = not detected.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
C12LAS (linear alkylbenzene sulfonate) was aerobically biodegraded in sediment (Lytle Creek). After 148 days, 60.8% was mineralized, 14.4% was associated with solids, 1.4% was metabolites, and 24.5% remained as parent. The rate constants for primary biodegradation and mineralization were 1.5 day-1 and 0.06 day-1, respectively.
Executive summary:

The biodegradation of C12LAS (linear alkylbenzene sulfonate) in sediment was evaluated in an aerobic die-away study using sediment from Lytle Creek, Wilmington, Ohio. Radiolabeled test material (14C) was used in a test design that was similar to OECD 308 and OECD 314. The test material was added to the sediment at 1.5 mg/Kg dry weight. The die-away study continued for 148 days. The test material was comprised of C10 -C13 alkyl chainlengths with an average chainlength of 11.6.

C12 -LAS was aerobically biodegraded in sediment from Lytle Creek. After 148 days:

60.8% was mineralized,

14.4% was associated with solids,

24.5% remained as parent, and

1.4% was metabolites.

Primary degradation was best described by a two compartment first order model (r2 > 0.99). The process was biphasic with two pools of material exhibiting different degradation rates. Pool A was presumably the more readily bioavailable test material in the aqueous phase. Pool B was presumably the less bioavailable test material bound to solids (sorbed). The rate constants for primary degradation were:

1.5 day-1 (pool A)

0.007 day-1 (pool B)

Mineralization (14CO2 production) was best described by a First Order Model (r2 > 0.99), indicating that parent and metabolites were equally bioavailable to undergo mineralization. The rate constant for mineralization was 0.06 day-1.