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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
Study period:
1979
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
Pre-guideline study performed equivalent to OECD 301 (1981)
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Version / remarks:
1981
Deviations:
no
Remarks:
no obvious deviations based on study report
GLP compliance:
not specified
Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure):
Sludge was taken from 10 different sites in Japan (municipal STPs, industrial STPs, lakes, rivers and bays)
- Laboratory culture: yes
- Method of cultivation: fresh and old sludge was mixed at regular intervals under sufficient aeration;
about 30 minutes after ceasing the aeration the supernatant corresponding to about 1/3 of whole volume was removed.
Then the equal volume of dechlorination water was added to the remaining portion and aerated again, followed by addition
of synthetic sewage* (0.1% w/v). This procedure was repeated once every day. The culturing was carried out at 25 °C.
- Storage conditions: see above
- Storage length: see above
- Preparation of inoculum for exposure: see above
- Pretreatment: see above
- Concentration of sludge: 30 mg/L

* Synthetic sewage: each 5% (w/v) glucose, peptone and monopotassium phosphate were dissolved in dechlorinatded water,
adjusted to pH 7.0 ± 1.0 with sodium hydroxide.

Duration of test (contact time):
14 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: basal mineral culture medium (according to the guideline)
- Additional substrate: no
- Solubilising agent (type and concentration if used): not necessary
- Continuous darkness: yes
- Test temperature: 25 °C +/- 1°C- pH: 7.0
- pH adjusted: yes
- Aeration of dilution water: pre-filtered air was used for aeration
- Suspended solids concentration: 30 mg/L
- Replicates for test item samples (with inoculum): n= 2

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes (n=1)
- Abiotic sterile control: yes (n= 2)
- positive control (reference): yes (Aniline), n=1;

TEST SYSTEM
- Culturing apparatus: 300 mL vessels ( Coulometer: Ohkura Electric Co., Ltd)
- Measuring equipment: Closed system oxygen consumption measuring apparatus
- Details of trap for CO2 and volatile organics if used: Soda lime No.1 (extra pure reagent)
Reference substance:
aniline
Parameter:
% degradation (O2 consumption)
Value:
85
Sampling time:
14 d
Remarks on result:
other: BOD / ThOD (without NH3 oxidation)
Key result
Parameter:
% degradation (O2 consumption)
Value:
66
Sampling time:
14 d
Remarks on result:
other: BOD /ThOD (including NH3 oxidation)
Parameter:
% degradation (TOC removal)
Value:
98
Sampling time:
14 d
Parameter:
other: HPLC analysis
Value:
100
Sampling time:
14 d
Details on results:
BOD test item flask A (300 ml; 100 mg/L test item; day 14) = BOD test item flask B (300 ml; 100 mg/L test item) = 68.4 mg;
BOD incoculum control (300 ml; day 14): 1.5 mg
Net-BOD (day 14) = 68.4 mg - 1.5 mg = 66.9 mg

ThOD_NH3: 2.63 mg O2/mg, i.e. 78.9 mg per 30 mg test item;
ThOD_NO2: 3.39 mg O2/mg, i.e. 101.7 mg per 30 mg test item;

% biodegradation (NH3) = 85%
% biodegradation (NO2) = 66%

Aniline:
BOD (day 14; 30 mg) = 69 mg; Net-BOD = 69 mg - 1.5 mg = 67.5 mg;
ThOD_NH3 Aniline: 2.405 mg O2/mg, i.e. 72.15 mg O2 per 30 mg for the test.
ThOD_NO2 Aniline: 3.01 mg O2/mg, i.e. 90.3 mg O2 per 30 mg for the test
% biodegradation (NH3) = 93.5%
% biodegradation (NO2) = 76.4%

10-day window requirement (based on plotted data within the report):
Biodegradation extent after 10 days:
BOD test item flask A (300 ml; 100 mg/L test item; day 14) = BOD test item flask B (300 ml; 100 mg/L test item) = 64.3 mg;
BOD incoculum control (300 ml; day 14): <1.5 mg
Net-BOD (day 14) = 64.3 mg - 1.5 mg = 62.8 mg
% biodegradation (NO2) = 62%
Results with reference substance:
Within 14 days:
% biodegradation (NH3) = 93.5%
% biodegradation (NO2) = 76.4%

The pass value has been reached in a 10-d window within the 28-d period of the test for all 7 replicates of the test substance.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
Based on reliable MITI-test I (OECD 301 C) the test item is readily biodegradable, fulfilling the 10-day window requirement.
Executive summary:

The test item n-butylamine was tested for ready biodegradability in a reliable study performed according to the MITI-I protocol (equivalent to OECD 301 C, 1981). All relevant data are given in the study report. Biodegradation extent (BOD) reached 85% and 66% without and including nitrification, respectively, within 14 days. The 10 day-window requirement was met (62% biodegradation incl. nitrification within 10 days). All validity criteria (based on OECD 301, 1992) were fulfilled.

Description of key information

Based on a reliable MITI-test I (OECD 301 C) the test item is readily biodegradable, fulfilling the 10-day window requirement.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

In the key study (CITI/NITE, 1979), the test item n-butylamine was tested for ready biodegradability in a reliable study performed according to the MITI-I protocol (equivalent to OECD 301 C, 1981). All relevant data are given in the study report. Biodegradation extent (BOD) reached 85% and 66% without and including nitrification, respectively, within 14 days. The 10 day-window requirement was met (62%

biodegradation incl. nitrification within 10 days). All validity criteria (based on OECD 301, 1992) were met.

The following supporting data are available, corroborating the result of the key study:

In a test on inherent biodegradability (Hoechst / Wellens, 1977), n-Butylamine underwent about 90 % and 100% biodegration within 2 and 5 days, respectively, based on determination of COD in the pre-guideline test equivalent to OECD 302B. This result is consitent with ready biodegradability as determined within the key study.

Further, biodegradation of n-butylamine was examined in a pre-guideline study (Yoshimura, 1980) that is comparable to the OECD TG 301-C (MITI-I) test for ready biodegradation. The BOD accounted for more than 50% of the ThOD (theoretical oxygen demand) after 5 days, and for more than 60 % after 12 days of culture.