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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:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: performed according to official test guideline and with GLP certificate
Qualifier:
according to
Guideline:
EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)
GLP compliance:
yes (incl. certificate)
Inoculum or test system:
other: activated sludge
Details on inoculum:
- Source of inoculum: laboratory activated sludge facility, connected to sewage water supply from "südlicher Wupperverband", Germany. Predominantly communal sewage water
- Treatment of inoculum: none
- Concentration of inoculum used in test: 30 mg dry matter/l
Duration of test (contact time):
27 d
Initial conc.:
100 mg/L
Reference substance:
aniline
Remarks:
min. 99.5 %
Key result
Parameter:
% degradation (O2 consumption)
Value:
75
Sampling time:
27 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
66
Sampling time:
12 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
35
Sampling time:
6 d
Key result
Parameter:
% degradation (O2 consumption)
Value:
8
Sampling time:
2 d

Overall result in study report:

In the test period of 27 days diethyl carbonate pure was degraded to 75 % (degradation after 10 d, see result table below).

The test substance was not found to be toxic to bacteria at the test concentration.

The reference substance aniline was degraded to 72 % in 14 days.

Result tables:

Test substance:

Time (days)   2 6 8 12 14 16 20 22 26 27
corrected BOD (mg O2/l) a1 / / / / / / / / / /
corrected BOD (mg O2/l) a2 11 54 79 107 110 113 116 121 123 123
corrected BOD (mg O2/l) a3 14 59 80 108 111 114 115 117 118 118
% degradation a1 / / / / / / / / / /
% degradation a2 7 33 49 66 68 70 71 74 76 76
% degradation a3 9 36 49 66 68 70 71 72 73 73
% degradation mean value   8 35 49 66 68 70 71 73 75 75

Theoretic O2 demand of the test substance: 1625 mg O2/g

Reference substance:

Time (days)   2 6 8 12 14 16 20 22 26 27
corrected BOD (mg O2/l) r1 0 0 0 164 174 180 190 196 200 201
corrected BOD (mg O2/l) r2 0 0 0 176 186 190 192 194 194 194
corrected BOD (mg O2/l) r3 0 0 0 143 164 170 176 182 186 187
% degradation r1 0 0 0 68 72 75 79 81 83 83
% degradation r2 0 0 0 73 77 79 80 81 81 81
% degradation r3 0 0 0 59 68 71 73 76 77 78
% degradation mean value   0 0 0 67 72 75 77 79 80 81

Theoretic O2 demand of the reference substance: 2409 mg O2/g

Toxicity control:

Time (days)   2 6 8 12 14 16 20 22 26 27
corrected BOD (mg O2/l) t1 2 93 245 313 319 325 333 337 339 339
corrected BOD (mg O2/l) t2 2 169 240 293 299 303 310 313 315 315
% degradation t1 0 23 61 78 79 81 83 84 84 84
% degradation t2 0 42 59 73 74 75 77 78 78 78
% degradation mean value   0 33 60 76 77 78 80 81 81 81
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Requirement for classification as readily biodegradable:
According to Guidance on information requirements and chemical safety assessment, Chapter R.7b: Endpoint specific guidance (ECHA, May 2008), 60 % of the ThOD need to be consumed at the end of the 28 d test period for OECD TG 301F (equivalent to EU Method C.4-D). Also, these pass levels have to be reached in a 10 d window within the 28 d period of the test, with the 10 d period beginning when the degree of biodegradation has reached 10 % DOC removal.

The results show that the criteria for the classification as readily biodegradable are fulfilled.

Description of key information

In the test period of 27 days diethyl carbonate pure was degraded to 75 % . The test substance was not found to be toxic to bacteria at the test concentration.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

After six days 35 % were degraded, after 16 days 70 % were degraded (10 -day window, Guidance on information requirements and chemical safety assessment, Chapter R.7b: Endpoint specific guidance, R.7.9.4 Evaluation of available information on degradation/ biodegradation, p. 171).