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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:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Considered adequate for assessment

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
Accumulation and depuration of sediment-sorbed C12- and C16-polychlorinated alkanes by oligochaetes (Lumbriculus variegatus)
Author:
Fisk AT, Wiens SC, Webster GRB, Bergman A and Muir DCG
Year:
1998
Bibliographic source:
Envir. Toxicol. Chem 17: 2019-2026.
Reference Type:
publication
Title:
Unnamed
Year:
2005

Materials and methods

Principles of method if other than guideline:
The half lives of two C16 chlorinated paraffins (representing the extremes of the typical chlorine contents in commercial production) were determined in sediment (containing oligochaetes)
GLP compliance:
not specified

Test material

Constituent 1
Reference substance name:
Medium-Chain Chlorinated Paraffin (MCCP)
IUPAC Name:
Medium-Chain Chlorinated Paraffin (MCCP)
Constituent 2
Reference substance name:
85525-85-9
IUPAC Name:
85525-85-9
Details on test material:
- Name of test material (as cited in study report): 14C-labelled C16H31Cl3 and C16H21Cl13
- Substance type: technical products
- Physical state: liquid
- Analytical purity: no data
- Impurities (identity and concentrations): no details on presence or absence of a stabiliser
- Composition of test material, percentage of components: C16 chlorinated paraffins, with 35 and 69% chlorination.
- Radiochemical purity (if radiolabelling): no data
- Specific activity (if radiolabelling): 22.7 and 25 mCi/mmol for the 35 and 69% chlorinated paraffins
- Locations of the label (if radiolabelling): Carbon 1 for the 35% chlorinated paraffin and uniformerly labelled for the 69% chlorinated paraffin
- Expiration date of radiochemical substance (if radiolabelling): no data
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not relevant
Radiolabelling:
yes

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
natural water / sediment
Details on source and properties of surface water:
- Details on collection (e.g. location, sampling depth, contamination history, procedure): Ekman dredge from Lake 468, an oligotrophic, uncontaminated lake at the Experimental Lakes Area (ELA), Ontario, Canada in October 1995
- Storage conditions: Stored at 4oC
Details on source and properties of sediment:
- Details on collection (e.g. location, sampling depth, contamination history, procedure): Ekman dredge from Lake 468, an oligotrophic, uncontaminated lake at the Experimental Lakes Area (ELA), Ontario, Canada in October 1995
- Storage conditions: Stored at 4oC under 1 cm of lake water
- Textural classification (i.e. %sand/silt/clay): 76/21/3
- Organic carbon (%):1.3-1.5 dry wt
- Sediment samples sieved: yes
Details on inoculum:
no data
Duration of test (contact time):
ca. 14 d
Initial test substance concentrationopen allclose all
Initial conc.:
ca. 47.1 other: ng/g (dry weight; C16 chlorinated paraffin; 35% Cl)
Based on:
test mat.
Initial conc.:
ca. 135 other: ng/g (dry weight; C16 chlorinated paraffin; 69% Cl)
Based on:
test mat.
Initial conc.:
ca. 264 other: ng/g (dry weight; C16 chlorinated parrafin; 69% Cl)
Based on:
test mat.
Parameter followed for biodegradation estimation:
radiochem. meas.
Details on study design:
no data
Reference substance
Reference substance:
other: dichlorinated alkanes

Results and discussion

Test performance:
no data
Half-life of parent compound / 50% disappearance time (DT50)open allclose all
Compartment:
sediment
DT50:
ca. 12 d
St. dev.:
1
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: C16 chlorinated paraffin; 35% Cl
Compartment:
sediment
DT50:
ca. 58 d
St. dev.:
58
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: C16 chlorinated paraffin; 69% Cl
Transformation products:
not measured
Details on transformation products:
no data
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
The r2 value for the degradation rates were greater than 0.93 for the 35 % chlorinated paraffin and 0.49 for the 69% chlorinated paraffin
Results with reference substance:
no data

Applicant's summary and conclusion

Conclusions:
In an aerobic sediment system containing oligochaetes (Lumbriculus variegatus), the half-lives of two 14C-labelled C16 chlorinated paraffins were estimated to be about 12 and 58 days for the 35% and 69% chlorinated paraffin, respectively.
Executive summary:

The half-lives of two 14C-labelled C16 chlorinated paraffins were estimated to be about 12 days and 58 days for the 35 and 69% chlorinated paraffin, respectively, in an aerobic sediment system (freshwater) containing oligochaetes (Lumbriculus variegatus). The extent of degradation was determined at day 0 and day 14 of the experiments based on the difference between toluene-extractable 14C measurements (taken to represent unchanged chlorinated paraffin) and total 14C measurements. The r2 value for the degradation rates were greater than 0.93 for the 35% chlorinated paraffin and 0.49 for the 69% chlorinated paraffin.

The RAR (EU, 2005) notes that the "results of this test should be treated with caution as the identity of the 14C present in the samples was not determined, and it was only assumed that the non-extractable 14C represented metabolites".

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