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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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study conducted in compliance with GLP regulations
Qualifier:
according to
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic (adaptation not specified)
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge from a municipal waste water treatment plant Mannheim, Germany
- Method of cultivation: The inoculum was collected from the aeration tank of the plant and aerated in the laboratory until use.
- Preparation of inoculum for exposure: A suitable aliquot of the activated sludge suspension was sieved by a finely woven mesh with a mesh size about 1 mm. The activated sludge suspension was pre-aerated for about 24 hours at a temperature of 22 ± 2 °C. On day of exposure the sludge was allowed to settle. After settling the supernatant was discarded and the remaining sludge suspension was filled up with tap water.
- Pretreatment:
- Concentration of sludge: The sludge of the suspension was adjusted to a concentration of 6.0 g/L dry weight. Aliquots of 5 mL were added to the test vessels to obtain a sludge concentration of 30 mg/L dry substance.


Duration of test (contact time):
21 d
Initial conc.:
ca. 50 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
The following test assays were prepared:
2 blank control assays (BC)
2 test substance assays (TS)
1 inhibition control assay (IH)
1 reference substance assay (RS)
1 assay for control of abiotic elimination (PC)
1 assay for control of adsorption (AC)
Reference substance:
aniline
Key result
Parameter:
% degradation (DOC removal)
Value:
90 - 100
Sampling time:
21 d
Details on results:
Kinetic of test substance (in %):
- Degree of biodegradation of the test substance at the end of:
- the ten-days window, DOC removal (mean value): 90 - 100 %
- the end of exposure, DOC removal (mean value): 90 - 100 %

10 = after 3 day(s)
50 = after 5 day(s)
>80 = after 9 day(s
90 = after 10 day(s)
>90 = after 21 day(s)

Duration of the adaptation phase (days): 3

Kinetic of reference substance (in %):
- Degree of Biodegradation of the reference substance after 14 days, DOC removal: 97 %


Results with reference substance:
14 days, DOC removal: 97 %

- Deviation of degree of biodegradation of the test substance at the end of exposure was <20%.

- Degree of biodegradation of the reference substance was >70% DOC after 14 days.

- Degree of biodegradation in the inhibition control was >35 % DOC after 14 days.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial (adaptation not specified)
Duration of test (contact time):
18 d
Initial conc.:
415 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
DOC removal
Key result
Parameter:
% degradation (DOC removal)
Value:
90 - 100
Sampling time:
18 d
Parameter:
% degradation (DOC removal)
Value:
25
Sampling time:
3 h
Interpretation of results:
other: easily eliminated from water
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP guideline study
Qualifier:
according to
Guideline:
other: ISO 16221 (Guidance for the determination of biodegradability in the marine environment)
Qualifier:
according to
Guideline:
ISO DIS 9439 (Ultimate Aerobic Biodegradability - Method by Analysis of Released Carbon Dioxide)
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
other: marine microorganisms
Details on inoculum:
Source: Marine organisms from filters of sea water aquaria at Luisenpark Mannheim, Germany.
Four filters were grounded and the extracts of the filters were diluted with synthetic sea water.

Pre-treatment of the inoculum:
After arrival in the laboratory about 800 ml inoculum solution was vigorous stirred for about 30 minutes, filtered with a 70 µm sieve and aerated in darkness at a temperature of 22 ± 2° C until usage. This inoculum solution was unwashed used for the test.
Duration of test (contact time):
28 d
Initial conc.:
20 mg/L
Based on:
DOC
Initial conc.:
50 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
- Test temperature: 22 +/- 2°C
Reference substance:
aniline
Key result
Parameter:
% degradation (CO2 evolution)
Value:
< 10
Sampling time:
28 d
Details on results:
- TOC = 404 mg/g; DOC = 404 mg/g;
- DOC elimination after 28 days: 10-20% DOC

Kinetic of test substance (in %):
ca. 3 after 3 day(s)
ca. 6 after 7 day(s)
ca. 11 after 14 day(s)
ca. 10 after 21 day(s)
ca. 10 after 28 day(s)
Kinetic of control substance (in %):
ca. 60 ... 70 after 14 day(s)
Results with reference substance:
- degradation of inhibition control(14 d): 30-40% CO2/ThCO2
Interpretation of results:
other: CO2 of ThCO2; poorly biodegradable (in the marine environment)

Description of key information

The substance is readily biodegradable according to OECD criteria.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The ready biodegradability of ‘2-Propyn-1-ol, compound with methyloxirane’ was tested in a GLP guideline study according to OECD 301 A (Ready Biodegradability: DOC Die Away Test). Based on DOC removal 90 - 100% biodegradation of the substance observed after 21 days by domestic activated sludge from a municipal sewage treatment plant [BASF SE, 2012]. Hence, the substance can be considered as ready biodegradable. This result is supported by an inherent biodegradability study, which was conducted according to OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test). Based on DOC removal 90 - 100% biodegradation of the substance was observed after 18 days by industrial activated sludge [BASF AG, 1987].

Additionally studies on biodegradation under marine environmental conditions are available. One study was conducted under GLP conditions in accordance with ISO 16221 (Guidance for the determination of biodegradability in the marine environment). Based on the CO2 evolution < 10% biodegradation were observed after 28 days by marine microorganisms [BASF SE, 2004]. However, a newer study performed according to OECD guideline 306 and GLP show 74% degradation after an incubation time of 63 days. This study clearly indicate the biodegradfability of the substance in the marine environment. The longer lag phase is based on the much lower microorganism concentration given in marine water.