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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:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
30 January 2003 - 5 March 2003
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP Compliant, guideline study, available as unpublished report, acceptable with restrictions
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
with the exception of the inoculum preparation which was performed ASTM D5864
Principles of method if other than guideline:
Additional exceptions reported none which would affected the quality or integrity of the study data
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Oxygen conditions:
other:
Inoculum or test system:
other: Activated Sludge supernatant
Details on inoculum:
activated sludge from the Clinton Sanitary Wastewater Treatment Plant, Annandale New Jersey
Duration of test (contact time):
28 d
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
Triplicate test systems were used to evaluate the iodegradability of the test and positive control substances at mean concentrations of 49.00 mg/L and 47.39 mg/L, respectively. Blank test systems, which did not
contain the test or positive control substance, were run concurrently in triplicate. The total suspended solids (TSS) of the activated sludge was determined to be 4.41 g/L. The inoculum was added at a 1% loading volume of sludge supernatant to test medium. The microbial count of the inoculum was 106 CFU/mL. One liter of test medium, which was aerated for 24 hours with carbon dioxide free air, was added to each one liter respirometer flask. The test substance was weighed in an air tight syringe and injected into the test medium. The test system was sealed immediately after addition of the test substance. . An aliquot of the positive control stock solution was added to the appropriate test flasks. An unacclimated activated sludge inoculum was used in this study. The inoculum was obtained from the Clinton Sanitary Wastewater Treatment Plant, Annandale, NJ, USA. The treatment plant receives domestic sewage. All test systems were placed on a Coordinated Environmental Services (CES) automated respirometer which automatically recorded the oxygen
uptake in general agreement with the OECD guideline. The 28-day study was conducted at a temperature range of 21.0°C to 22.2°C.
Reference substance:
other: Sodium Benzoate
Preliminary study:
no data
Test performance:
no data
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Details on results:
No measurable biodegradation observed over a 28 day testing period.
DCPD/Codimer Concentrate cannot be considerd readily biodegradable
Results with reference substance:
Sodium benzoate biodegraded to >60% by day 2 and the average of the cumulative oxygen consumed in the blank systems was 22.35 mg/l.

No measurable biodegradation observed over a 28 day testing period. DCPD/Codimer Concentrate cannot be considerd readily biodegradable

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
Under the test conditions used no biodegradation was observed. DCPD/Codimer had biodegraded by 0% in 28 days.
Executive summary:

This study was GLP compliant and followed guidelines. The study is considered adequate for assessment. Under the test conditions used no biodegradation was observed. DCPD/Codimer had biodegraded by 0% in 28 days.

Description of key information

DCPD is not readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

A study for DCPD/Codimer Concentrate (CAS 68478-10-4) was available for review (Exxon Mobil, 2004) and was considered suitable for read across. The ready biodegradability study using activated sludge following OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) showed no biodegradation after 28 days. TheDCPD/Codimer Concentrate consists of dicyclopentadiene and codimers of cyclopentadiene. The substance consists of DCPD along with lower concentrations of other codimers of cyclopentadiene which have similar structures to DCPD and are expected to have similar biodegradation properties. Therefore, read across of this conservative result to DCPD is considered robust.

Information from MITI Japan indicating that the substance was not readily biodegradable was unavailable for review. However, this study is from a regulatory source and has been used in the OECD SIDS and therefore is included as a supporting study.

The use of a QSAR to predict the biodegradability of 3a,4,7,7a-tetrahydro-4,7-methanoindene is an appropriate technique to use as part of a weight of evidence approach. The use of BioHCwin and Biowin is appropriate for 3a,4,7,7a-tetrahydro-4,7-methanoindene as this compound clearly falls within the applicability domains of these models as all substructures in 3a,4,7,7a-tetrahydro-4,7-methanoindene are included in the models. The results from both QSAR indicate that 3a,4,7,7a-tetrahydro-4,7-methanoindene is expected not to be readily biodegradable.