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Environmental fate & pathways

Biodegradation in water: screening tests

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Administrative data

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2002
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Reliability rating was 2 because study followed OECD 301F test guidelines but was not carried out under GLP conditions. Study was scientifically accepted and well-documented.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): MCP 968
- Physical state: Liquid
- Analytical purity: 100%

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
The inoculum used was obtained from Somerset-Raritan Valley Sewage Treatment plant at Bridegeway NJ. The total suspended solids (TSS) was determined to be 3.04 g/L. The activated sludge sample was homogenized in a blender for two minutes at low speed. The homogenate sample was allowed to settle for 35 min after which the supernatant was decanted. The sludge supernatant used for the final preparation of the test medium solution on the day before the start of testing, was added at a 1% loading volume of the sludge supernatant to the appropriate test medium. The microbial activity of the inoculum was determined to en 1 x 10 E+6 CFU/ml.
Duration of test (contact time):
28 d
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (O2 consumption)
Value:
ca. 19.3
St. dev.:
5.2
Sampling time:
28 d
Remarks on result:
other: Max 25.2%
Details on results:
Max 25.2% biodegradation was observed in one vessel (n=3). The substance showed a long lag time before biodegradation began to take place (after day 15) and kinetic curve indicate that biodegradation was still lineat and continuing to proceed even at day 28.

BOD5 / COD results

Results with reference substance:
Sodium benzoate was biodegraded to 89.8% in 28 days.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
inherently biodegradable
Conclusions:
Using the OECD 301F manometric respirometry test guidelines, the aerobic ready biodegradability was evaluated for the test substance using unacclimated sewage inocula. Oxygen consumption was monitored to determine the ultimate aerobic biodegradation. The test substance was sufficiently biodegraded to the extent of 19.3 % in 28 days. If biodegradation of the test substance had been monitored past 28 days, the test substance would most likely be expected to reach the inherently biodegradable of 20% mark or greater. In fact, the highest biodegradation reached by one of the three test vessels was 25.2% in 28 days in the experiments. Based on these findings, the submission substance would be expected to be inherently biodegradable. There was an apparent lag phase before biodegradation occurred with the submission substance.
Executive summary:

The submission substance would be expected to be inherently biodegradable based on OECD 301 F ready biodegradation test findings.and based on the discussion above.