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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:
June 18 - August 28, 2009
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Physical state: solid
- Purity test date: 98.56%
- Lot/batch No.: 1508G21
- Expiration date of the lot/batch: 7/29/13
- Storage condition of test material: ambient, away from direct sunlight
- Other: carbon content 68.98%

Study design

Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
The facility treats predominantly residential wastes. The sludge was sieved using a 2 mm screen, adjusted to approximately 1,000 mg total suspended solids (TSS)/L with mineral media and then aerated at test temperature until use. A total suspended solids measurement and standard plate count were performed on the inoculum on the day of test chamber preparation. Plates were incubated at 20+/- 3 °C for approximately 48 hours.
Duration of test (contact time):
28 d
Initial test substance concentration
Initial conc.:
10 mg/L
Based on:
test mat.
Details on study design:
The test contained a blank control group, a reference group and a treatment group.Each group contained three replicate test chambers.The control group was used to measure the background CO2 production of the inoculum and was not dosed with a carbon source. The reference group chambers were used to check the viability of the inoculum and were dosed with sodium benzoate, a substance known to be biodegradable at a nominal conc of 10 mg C/L. The treatment group chambers were used to evaluate Uvasorb HEB at a nominal concentration of 10 mg C/L.
Reference substance
Reference substance:
benzoic acid, sodium salt

Results and discussion

% Degradation
Parameter:
% degradation (CO2 evolution)
Value:
6
Details on results:
The final mean percent biodegradation for Uvasorb HEB was 6.0%. Uvasorb HEB may not be considered readily biodegradable, since the pass level of 60% TCO2 was not achieved with 10 days of reaching 10% TCO2.

Any other information on results incl. tables

Measured dissolved organic carbon (DOC) on day 29 (10 mg C/L): <1.0. pH values of the test chamber contents on day 28: 7.1.

The measured concentrations of inorganic carbon in the carbon dioxide trapping solutions are presented in Table 2 (attached below). The cumulative amounts of CO2 produced over the test period are presented in Table 3 (attached below). The cumulative percent of theoretical carbon dioxide (% TCO2) evolved is presented in Table 4 (attached below).

The control chambers evolved an average of 70.3 mg CO2 over the test period. This value has been corrected for the amount of CO2 in the trapping solution since potassium hydroxyde solution, even when freshly prepared, contains carbonates. The amount of CO2 evolved by the control chambers did not exceed the 40 mg/l (120 mg total) value considered the acceptable limit for CO2 evolution tests. The viability of the inoculum and validity of the test were supported by the results of the reference substance from which an average of 95.6% of theoretical CO2 was evolved. An average % biodegradation of greater than 60% was achieved by Day 13 thereby fulfilling the criteria for a valid test by reaching the pass lev el by Day 14.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Interpretation of results:
not inherently biodegradable
Conclusions:
The final mean percent biodegradation for Uvasorb HEB was 6.0%. Uvasorb HEB may not be considered readily biodegradable, since the pass level of 60% TCO2 was not achieved with 10 days of reaching 10% TCO2.