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Environmental fate & pathways

Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: screening test, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
18 January 1994 to 15 February 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Qualifier:
according to guideline
Guideline:
OECD Guideline 306 (Biodegradability in Seawater)
Deviations:
yes
Remarks:
No details on the tested substance
GLP compliance:
yes (incl. QA statement)
Remarks:
Date: 21 March 1994
Specific details on test material used for the study:
No details
Oxygen conditions:
aerobic
Inoculum or test system:
natural water: marine
Remarks:
sampling site:Byfjord, Bergen, Norway
Duration of test (contact time):
28 d
Initial conc.:
3.08 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Key result
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Remarks on result:
not determinable because of methodological limitations
Remarks:
Test item toxic to the inoculum at tested concentration
Details on results:
Kinetic of control substance (in %):
= 71.6 after 5 day(s)
= 90.8 after 28 day(s)

The test substance was inhibitory at the test concentration used. The other validity criteria were met.

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Remarks:
The test substance can be considered to be inhibitory to bacteria at the concentration used.
Conclusions:
No biodegradation was observed (0%) after 28 days under the test conditions. However, a toxicity test performed with the test substance indicated that the test substance was inhibitory at the test concentration used. Therefore, this study doesn't allow to assess the biodegradability of THPS in seawater.
Executive summary:

This study was performed according to OECD Guideline 306 with GLP statement to assess the biodegradability of the test substance (THPS at a concentration of 3.08 mg/L) in seawater (closed bottle test). During the test and after the 28 days exposure period, no biodegradation was observed (0%). The validity criteria's for this test have been met: O2 consumption in blank flasks did not exceed 30% of the available oxygen; degradation of the reference substance reached 50% within 5 days (not including any lag phase). However, a toxicity test performed with the test substance indicated that the test substance was inhibitory at the test concentration used. Therefore, this study doesn't allow to assess the biodegradability of THPS in seawater.

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
1985
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
No toxicity control has been carried out in the study. However at the test substance concentration used (100 mg C/l, equivalent to ca. 420 mg/l of anhydrous active substance), toxicity to the inoculum is highly expected (see section 6.1.7. Toxicity to microrganisms). Therefore, this study is considered to underestimated the inherent biodegradability of the tested substance.
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Deviations:
yes
Remarks:
No toxicity control has been carried out in the study.
Principles of method if other than guideline:
Not applicable
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Duration of test (contact time):
42 d
Initial conc.:
100 mg/L
Based on:
DOC
Reference substance:
diethylene glycol
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
8 d
Key result
Parameter:
% degradation (DOC removal)
Value:
27
Sampling time:
14 d
Remarks on result:
other: Inherently biodegradable
Parameter:
% degradation (DOC removal)
Value:
28
Sampling time:
28 d
Parameter:
% degradation (DOC removal)
Value:
37
Sampling time:
42 d
Details on results:
Biodegradation of the test substance (in %):
= 4 after 3h
= 0 after 1, 3 and 6 day(s)
= 2 after 2 days
=11 after 10 days
= 29 after 16 days
= 35 after 21 day(s)
= 34 and 31 (analysed by Bostock, Hill and Rigby Ltd) after 23 days
= 23 (analysed by Bostock, Hill and Rigby Ltd) after 28 day(s)
33 (analysed by Bostock, Hill and Rigby Ltd) after 30d
= 23 (analysed by Bostock, Hill and Rigby Ltd) after 35 days
= 26 (analysed by Bostock, Hill and Rigby Ltd) after 37 days

Kinetic of control substance (in %):
= 44 after 8 day(s)
= 100 after 14 day(s)
Results with reference substance:
100% degradation after 28 days

No toxicity control has been carried out in the study. However at the test substance concentration used (100 mg C/l, equivalent to ca. 420 mg/l of anhydrous active substance) toxicity to the innoculum is highly expexted (See section 6.1.7. toxicity to microorganisms)

Validity criteria fulfilled:
yes
Remarks:
No toxicity control has been carried out in the study.
Interpretation of results:
not inherently biodegradable
Conclusions:
The test substance attained more than 20% degradation within the 28 day period and may therefore be classed as inherently biodegradable under the criteria of OECD Guideline 302B. No toxicity control has been carried out in the study. However at the test substance concentration used (100 mg C/l, equivalent to ca. 420 mg/l of anhydrous active substance) toxicity to the innoculum is highly expexted. Therefore, this study is considered invalid.
Executive summary:

This study was performed according to OECD Guideline 302B with GLP statement to assess the inherent biodegradability of the test substance. The carbon content and the percentage of bioelimination were calculated for the test substance and the reference substance (diethylene glycol). In order to investigate the possibility of further degradation of the test substance over an extended period, the experiment was continued for a further 14 days (total (d): 28 + 14 = 42 days). The test substance attained more than 20% degradation within the 28 day period and may therefore be classed as inherently biodegradable under the criteria of OECD Guideline 302B. There is little indication that any appreciable increase in degradation took place during the 14 day extension of the experiment. No toxicity control has been carried out in the study. 

No toxicity control has been carried out in the study. However at the test substance concentration used (100 mg C/l, equivalent to ca. 420 mg/l of anhydrous active substance) toxicity to the innoculum is highly expexted

(see section 6.1.7. Toxicity to microrganisms). Therefore, this study is considered invalid due to suspected toxicity to inoculum.
Endpoint:
biodegradation in water: screening tests
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
Study period:
1984
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
documentation insufficient for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
BOD5 Method: other
GLP compliance:
no
Oxygen conditions:
not specified
Inoculum or test system:
not specified
Duration of test (contact time):
5 d
Initial conc.:
1 mg/L
Based on:
other: Test substance
Reference substance:
other: Glucose/glutamic acid
Details on results:
No data
Parameter:
BOD5
Value:
< 0.1 g O2/g test mat.
Parameter:
COD
Value:
752 mg O2/g test mat.
Parameter:
BOD5*100/COD
Value:
< 13

Test substance:

BOD5 < 0.1 g O2/g (oxygen uptake below the detection limit)

COD = 0.752 g O2/g

TOC = 0.11 g C/g

Reference substance (Glucose/glutamic acid):

BOD5 = 183 mg O2/l

TOC = 123 mg C/l

Toxicity: 20 % inhibition of glucose/glutamic acid acid BOD5 at the lowest tested concentration of 1 mg/l of test substance.

Validity criteria fulfilled:
not applicable
Remarks:
No guideline followed
Conclusions:
The BOD5 of the test substance is lower than 13.0% of the COD indicating that it is readily biodegradable. The toxicity data indicate the the IC50 value (concentration causing 50% inhibition of glucose/glutamic acid oxidation) lies between 32 and 100 mg/L. As toxicity to inoculum was observed, this study is considered invalid.
Executive summary:

This study was not performed according to international guideline neither on GLP compliance. The BOD5 (Biochemical Oxygen Demand, 5 day), TOC (Total Organic Carbon), COD (Chemical Oxygen Demand) and the bacterial inhibition by the glucose/glutamic acid was evaluated at concentrations of 1, 3.2, 10, 32 and 100 mg test substance/L. According to the results of this study, the BOD5 of the test substance is lower than 13.0% of the COD indicating that it is readily biodegradable. The toxicity data indicate the IC50 value (concentration causing 50% inhibition of glucose/glutamic acid oxidation) lies between 32 and 100 mg/L. As toxicity to inoculum was observed, this study is considered invalid.

Description of key information

The available tests relevant for ready biodegradability (OECD 306 and BOD/COD) and inherent biodegradability (OECD302B) are invalidated due to toxicity of THPS towards the inoculum at the recommended test concentrations (Hill, 1984a; Douglas, 1985a; Mc Williams, 1994).

Therefore two simulation tests were performed at environmental relevant concentrations in freshwater/sediment test systems, under aerobic and anaerobic conditions. Both studies have been defined reliable (see IUCLID section 5.2.2) and showed that THPS is inherently biodegradable (70% ultimate degradation before Day 28) under aerobic conditions (70% mineralisation at Day21) and rapidly biodegradable (DT50 mineralisation< 16 days) under aerobic (DT50 mineralisation= 2 days) and anaerobic (DT50 mineralisation= 14 days) conditions.

For the purpose of risk assessment, the substance is assessed as inherently biodegrabale or rapidely biodegradable under relevant environmental conditions. For CLP purposes the substance is assessed as rapidely degradable.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information