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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
10.2004 - 11-2004
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Initial conc.:
50 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
acetic acid, sodium salt
Parameter:
% degradation (CO2 evolution)
Value:
100
Sampling time:
21 d
Results with reference substance:
82 % after 14 days and 100 % after 28 days
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The test item reached the 10 % level (beginning of biodegradation) after an adaptation phase of 4 days. The biodegradation was rapid and reached the pass level of 60 % already on day 10. The biodegradation came to a maximum of 100 % after 21 days.
Executive summary:

The ready biodegradability was determined with a non adapted activated sludge for the test item over a period of 28 days in the Modified Sturm Test. The test item was tested with a concentration of 50 mg/L in duplicates, corresponding to a carbon content (TOC) of 12.4 mgC/L in the test vessels. The biodegradation of the test item was followed by titrimetric analyses of the quantity of CO2 produced by the respiration of bacteria. The degradation was finished on day 28 by acidification; the last titration was made on day 29. The percentage Co2 production was calculated in relation to the theoretical CO2 (ThCo2) of the test item. The biodegradation was calculated for each titration time.

To check the activity of the test system sodium acetate was used as functional control. The percentage degradation of the functional control reached the pass level of 60 % after 8 days. In the toxicity control containing both test and reference item a biodegradation rate of 82 % occurred within 14 days and came to a maximum of 100 % after 28 days. The test item in the toxicity control did not inhibit the biodegradation of the reference item.

The test item reached the 10 % level (beginning of biodegradation) after an adaptation phase of 4 days. The biodegradation was rapid and reached the pass level of 60 % already on day 10. The biodegradation came to a maximum of 100 % after 21 days.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
11.93 - 12.93
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
Deviations:
not specified
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
STP Niederrad
Duration of test (contact time):
28 d
Initial conc.:
>= 5 - <= 40 mg/L
Based on:
DOC
Parameter:
% degradation (DOC removal)
Value:
88
Sampling time:
28 d
Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
The test item is readily biodegradable in 10 -d window 86 % and after 28 d (88%)
Executive summary:

The test item is readily biodegradable in 10 -d window 86 % and after 28 d (88%)

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP guideline study with acceptable restrictions (test performance is briefly reported)
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
- - Source of inoculum/activated sludge: not specified
Duration of test (contact time):
28 d
Initial conc.:
>= 5 - <= 40 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
TEST CONDITIONS
- Composition of medium: anorganic nutrient solution containing micronutrients and essential vitamines
- Test temperature: 20 - 25 °C
- Continuous darkness: yes

TEST SYSTEM
- Other: The test solution was placed on a mechanical shaker

SAMPLING
- Sampling frequency: Samples were taken after 7, 14, 21, 27 and 28 days.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes, a trial without the test or reference substance was conducted

Reference substance:
benzoic acid, sodium salt
Parameter:
% degradation (DOC removal)
Value:
94.4
Sampling time:
28 d
Details on results:
The test substance reached a biodegradation of 94.4% within a test period of 28 days. The 10 day-window was met. Thus, the test substance is readily biodegradable according to OECD criteria.
Results with reference substance:
The reference substance was biodegraded to 97.9% within 28 days.

Table 1: Biodegradation of reference and test substance in % DOC removal throughout the test period of 28 days

Days

Reference substance

Test substance

7

93.0

81.4

14

97.8

90.5

21

97.2

93.0

27

97.8

95.5

28

97.9

94.4

Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2008-10-15 to 2008-11-13
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study according OECD Guideline and GLP, no deviations from Guideline, biodegradation equal/better than reference item sodium benzoate, toxicity control demonstrated no inhibitory effect of the test item
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Duration of test (contact time):
28 d
Initial conc.:
108 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Reference substance:
benzoic acid, sodium salt
Remarks:
at 20 mg/L
Parameter:
% degradation (CO2 evolution)
Value:
83 - 86
Sampling time:
28 d
Details on results:
Lag time was 1.5 d, Degradation time was 13.5 d, 10d window achieved (10% at day 1.5 and 60% at day 8)
Results with reference substance:
validity criteria was met based on degradation curve

In a toxicity test containing both the test item and the reference item >25% biodegradation was achieved within 14d and 84% after 28d. This means that the test item is not inhibitory.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Executive summary:

The biodegradability of the test item Hostapon SG (24,6% a.i. SCG) was investigated in an OECD 301B ready test with non-adapted inoculum over a period of 28d. The initial test item concentration was 108 mg/L. 83 -86% Biodegradation was achieved after 28d. The 10% level of degradation was reached after 1.5d and the 60% pass level after 8d. In a toxicity test with the reference substance sodium benzoate it was demonstrated that the test item in not inhibitory.

Based on the results given before the test item Hostapon SG is readily biodegradable fulfilling the 10d window.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Justification is provided in the separate statement.
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Parameter:
% degradation (CO2 evolution)
Value:
86
Sampling time:
28 d
Interpretation of results:
readily biodegradable
Executive summary:

In three studies with two different supporting substances (structural analogue or surrogate) ready biodegradability could be shown in the 10 -d windows and after the 28 day period.

Description of key information

In a Key study with the test item it could be shown that the test item reached the 10 % level (beginning of biodegradation) after an adaptation phase of 4 days. The biodegradation was rapid and reached the pass level of 60 % already on day 10. The biodegradation came to a maximum of 100 % after 21 days.

In three studies with two different supporting substances (structural analogue or surrogate) ready biodegradability could be shown in the 10 -d windows and after the 28 day period.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information