Isopropylamine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1996-12-04 to 1997-02-07 (experimental phase)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

adopted July 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Laboratory STP treating domestic and synthetic sewage
- Method of cultivation: activated sludge was sampled from laboratory STP, washed and aerated for 24 h
- Concentration: 30 mg/L /dry weight)

Duration of test (contact time):

35 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS:
- Temperature of incubation °C: room temperature
- Dosing procedure: Direct addition to test medium

CONTROL AND BLANK SYSTEM
- Appropriate controls and blank system used: yes
- blank values (BW)
- biodegradation of a reference substance (RS)
- inhibition of the inoculum (IH)
- abiotic elimination (PC)
- Analytical method used to measure biodegradation: BOD
- pH: was measured at test start (day 0) and test end (day 35)
- Concentration of activated sludge in test vessels: 30 mg/L (dry weight)

TEST SYSTEM
- Culturing apparatus: Respirometer flaks
- Number of culture flasks/concentration: 7
- Method used to create aerobic conditions: 24h aeration of activated sludge befor the start of the test; oxygen used during the test is continuously replenished (and measured)

SAMPLING
- Sampling frequency: continuously for 35 days

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

72

Sampling time:

28 d

Remarks on result:

other: mean value (TS1-TS4): 72 % (nitrification not considered but nitrification negligible)

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

35 d

Remarks on result:

other: mean value (TS1-TS7): 73% (nitrification not considered)

Parameter:

% degradation (O2 consumption)

Value:

70

Sampling time:

35 d

Remarks on result:

other: mean value (TS1-TS4): 70 % (corrected for nitrification)

Parameter:

% degradation (O2 consumption)

Value:

116

Sampling time:

35 d

Remarks on result:

other: mean value (TS5-TS7): 116 % (nitrification not considered)

Parameter:

% degradation (O2 consumption)

Value:

83

Sampling time:

35 d

Remarks on result:

other: mean value (TS5-TS7): 83 % (corrected for nitrification)

Details on results:

Reference control (KS):
- reference substance: aniline
- concentration: 100 mg/L related to reference substance
- kinetic of reference substance: 8 day(s) 3 % BOD/ThOD
9 day(s) 15 % BOD/ThOD
12 day(s) 46 % BOD/ThOD
13 day(s) 62 % BOD/ThOD
28 day(s) 82 % BOD/ThOD
35 day(s) 83 % BOD/ThOD

Inhibition control (IH):
- substances: aniline + isopropylamine
- concentration: each 100 mg/L related to substance
- kinetic of inhibition control: 7 day(s) 0 % BOD/ThOD
14 day(s) 1 % BOD/ThOD
18 day(s) 24 % BOD/ThOD
19 day(s) 46% BOD/ThOD
21 day(s) 56 % BOD/ThOD
28 day(s) 72 % BOD/ThOD
35 day(s) 74 % BOD/ThOD


Assay to examine physico-chemical elimination (abiotic control; PC):
- concentration: 100 mg/L related to test substance
- w/o inoculum, w mercury chloride to avoid biodegradation
- kinetic of physico-chemical elimination:
7 day(s): 0 % BOD/ThOD
14 day(s): 0 % BOD/ThOD
21 day(s): 0 % BOD/ThOD
28 day(s): 1 % BOD/ThOD

The test substance was measured in 7 replicates.
NO3-N and N02-N concentration measured in vessels containing the test substance at test end (after 35 day(s)):
- assay NO2-N NO3-N
(mg/L) (mg/L)
TS1 0.0 1.61
TS2 0.0 2.99
TS3 0.0 1.61
TS4 0.0 0.92
TS5 0.0 18.4
TS6 0.0 25.3
TS7 0.0 9.2

Biodegradation (%) in relation to the ThOD corrected for oxygen demand due to nitrification at test end (after 35 day(s)):
- assay BOD/ThOD BOD/ThOD
% (1) % (2)
TS1 75 72
TS2 77 72
TS3 78 75
TS4 61 59
TS5 126 91
TS6 124 77
TS7 99 82
(1) = nitrification not considered; (2) corrected for nitrification

Nitrification in the replicates TS1 to TS4 was regarded as negligible. At least these assays were considered to evaluate the biodegradability of isopropylamine (70-80 %) BOD/ThOD after 28 days).
Biodegradation % BOD/ThOD
- after 28 day(s):
mean value (TS1-TS4): 72 % (nitrification not considered); individual values: TS1=74%, TS2=76, TS3=77%, TS4=60%
mean value (TS5-TS7): 109 % (nitrification not considered)
- at test end (after 35 day(s)):
mean value (TS1-TS4): 73 % (nitrification not considered)
mean value (TS1-TS4): 70 % (corrected for nitrification)
mean value (TS5-TS7): 116 % (nitrification not considered)
mean value (TS5-TS7): 83 % (corrected for nitrification)

pH values at test start and test end (after 35 day(s)):
- assay pH pH
day 0 day 35
BC1 7.6 7.7
BC2 7.6 7.7
RS 7.6 9.1
IH 10.0 9.0
TS1 10.0 7.4
TS2 10.0 7.4
TS3 9.9 7.4
TS4 10.0 7.4
TS5 9.9 6.3
TS6 10.1 6.6
TS7 10.1 7.0
PC 10.1 7.4

Kinetic of test substance (in %):
< 10 after 8 day(s)
> 50 after 10 day(s)
ca. 60 after 12 day(s)
= 70 ... 80 after 28 day(s)
= 70 ... 80 after 35 day(s)

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:
1) The percentage degradation of the reference compound has reached pass levels by day 14 (73% biodegradation) but the difference of extremes of replicate values of the removal of the test chemical at the end of the test is more than 20%. However, seven replicates were tested for the test substance although only two replicates are required according to OECD 301F.
The increased variability is due to the heterogeneous nitrification between the replicates; in the test group with low nitrification (TS1-TS4) the variability is only slightly above the limit of 20% (nitrification not considered: 21.8%; nitrification considered: 21.3%). Since all replicates pass the ready biodegradability level of 60% of ThOD, the slightly increased variability between the replicates leaves no doubt as to the ready degradability of the substance.

2) The degradation in the inhibition control was less than 25% (based on ThOD) within 14 days; degradation > 25% was only observed on day 19 (46%). However, a general inhibition of the inoculum is not to be expected since all other vessels (except the abiotic control; PC) showed biodegradation within 14 days.

Results with reference substance:

See IUCLID section 'Details on results'

Validity criteria fulfilled:

yes

Remarks:

for details see IUCLID section 'Overall remarks, attachments'

Interpretation of results:

readily biodegradable

Conclusions:

Based on a reliable Manometric Respirometry Test (OECD Guideline 301 F) the test item is readily biodegradable, fulfilling the 10-day window requirement.

Executive summary:

The test item isopropylamine was tested for ready biodegradability in a reliable Manometric Respirometry Test (OECD Guideline 301 F; adopted July 1992). All relevant data are given in the study report. Biodegradation extent (BOD) reached 72% (mean value of replicates TS1-TS4; nitrification not considered but nitrification negligible) within 28 days; 60% biodegradation occurred approximately after 12 days.

Nitrification was measured at test end (day 35), biodegradation corrected for nitrification was 70% (mean value) for replicates TS1-TS4 and 83% (mean value) for replicates TS5-TS7 within 35 days.

The 10 day-window requirement was met (approximately 60% biodegradation within 12 days).

For the test group with low nitrification (TS1-TS4), the difference of extremes of replicate values of the removal of the test chemical at the end of the test is less than 20%. All replicates (TS1 -TS7) pass the ready biodegradability level of 60% of ThOD (except one replicate, where 59% of ThOD were biodegradaed).

The delayed degradation inthe inhibition control (less than 25% based on ThOD within 14 days but 46% at day 19) does not indicate ageneral inhibition of the inoculum since all other vessels showed high biodegradation within 14 days.

Accordingly, the study is considered valid and ready biodegradability can reliably be concluded for the test item.

Description of key information

Based on a reliable Manometric Respirometry Test (OECD Guideline 301 F) 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

The submission substance isopropylamine was tested in a reliable GLP-compliant study for ready biodegradability according OECD Guideline 301 F (BASF 1997). Seven replicates were incubated together with inoculum control, abiotic control, reference item (anline) and inhibition control (IC).

Biodegradation extent (BOD) reached 72% (mean value of replicates TS1-TS4; nitrification not considered but nitrification negligible) within 28 days; 60% biodegradation occurred approximately after 12 days.

Nitrification was measured at test end (day 35), biodegradation corrected for nitrification was 70% (mean value) for replicates TS1-TS4 and 83% (mean value) for replicates TS5-TS7 within 35 days.

The 10 day-window requirement was met (approximately 60% biodegradation within 12 days).

For the test group with low nitrification (TS1-TS4), the difference of extremes of replicate values of the removal of the test chemical at the end of the test is less than 20%. All replicates (TS1 -TS7) pass the ready biodegradability level of 60% of ThOD (except one replicate, where 59% of ThOD were biodegraded).

The delayed degradation in the inhibition control (less than 25% based on ThOD within 14 days but 46% at day 19) does not indicate a general inhibition of the inoculum since all other vessels showed high biodegradation within 14 days. pH was significantly higher (more alkaline) in the inhibition control compared to the other vessels, which may be due to the additional amine (aniline) present. This most probably was causative for the delay in biodegradation, while 72% mineralisation was reached within 28 days in the inhibition control.

Accordingly, the study is considered valid and ready biodegradability can reliably be concluded for the test item.

Supporting Data are available which corroborate the result of the reliable key study:

In a pre-guideline test equivalent to OECD 302B (Hoechst 1980), isopropylamine was assessed for inherent biodegradability. Because biodegradation based on O2 consumption was very fast (>90 % and 83% biodegradation within 10 and 5 days, respectively) the results of this test are consistent with ready biodegradability and thus in support of the key study.

In a further test on ready biodegradability (Arkema, 1992) performed according to OECD Guideline 301 A, DOC removal was examined for 21 days with an initial DOC concentration of 30.0 mg/L. The results show that 95% of the test substance were removed within 21 days. Accordingly, the substance was determined to be readily biodegradable.

[Type of water: freshwater]