3-iodo-2-propynyl butylcarbamate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2002-03-11

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:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 0004-1545

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: wastewater treatment plant, ARA Ergolz II, FQIIinsdorf, Switzerland
- Preparation of inoculum for exposure: The sludge was washed once with tap water by centrifugation and the supernatant liquid phase was decanted. A homogenized aliquot of the final sludge suspension was weighed, thereafter dried and the ratio of wet to dry weight was calculated
- Concentration of sludge: final concentration 30 mg per liter (dry weight)

Duration of test (contact time):

28 d

Initial conc.:

50 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: test water was prepared according to guidelines
- Solubilising agent: no solvent was used, but ultrasonic dispersion was performed
- Test temperature: 22 °C, checked once a week
- pH: Prior to test start, the pH was 7.4 (measured in each test flask after the addition of the activated sludge inoculum). At the end of incubation, the pH was measured again in each test flask
- pH adjusted: no
- Aeration of dilution water: yes
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: test flasks 500 mL Erlenmeyer flasks
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: continuous stirring

SAMPLING
- Sampling frequency: oxygen consumption was recorded manually by daily reading

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: yes
- Toxicity control: yes

STATISTICAL METHODS:
The percentage biodegradation was calculated according to the below given formula:

% biodegradation = [BOD (mgO2/mg chemical) / ThOD (mgO2/mgchemical)] x 100

where

BOD = Biochemical oxygen demand of the test or reference item

= (mgO2 uptake/L by test and/or reference item) – (mgO2 uptake/L by inoculum control) / mg test and/or reference item per liter

Reference substance:

benzoic acid, sodium salt

Preliminary study:

Based on the results of the "Respiration Inhibition Test" the test item concentration was reduced in this manometric respirometry test from normally 100 mg/L to about 50 mg/L to avoid a possible inhibitory effect of IPBC on the activity of activated sludge microorganisms.

Key result

Parameter:

% degradation (O2 consumption)

Sampling time:

28 d

Remarks on result:

not determinable

Details on results:

BOD of the test item in the test media was found to be lower than in the inoculum controls. Thus, the test item is considered to be not biodegradable.

Results with reference substance:

In the procedure controls, the reference item sodium benzoate was biodegraded by an average of 97% on exposure Day 14, and reached an average biodegradation rate of 96% by the end of the test (Day 28), thus confirming suitability of the activated sludge.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

Under the conditions of this study, the test item is considered to be not biodegradable within 28 days.

Executive summary:

The test item was investigated for its ready biodegradability in a manometric respirometry test over 28 days based on EU Commission Directive 92/69 EEC, C.4 -D (1992) and OECD Guideline for Testing of Chemicals No. 301 F (1992).

Based on the results of the "Respiration Inhibition Test" the test item concentration was reduced in this manometric respirometry test from normally 100 mg/L to about 50 mg/L to avoid a possible inhibitory effect of the test item on the activity of activated sludge microorganisms. This reduced concentration is slightly below the EC20 of test item in the respiration inhibition test (57 mg/L) and is in compliance with the testing guidelines.

The percent biodegradation of the test item was calculated based on the theoretical oxygen demand of 1.03 mg O2/mg test item without nitrification (ThODNm) and 1.25 mg O2/mg test item with nitrification (ThODN03).

The biochemical oxygen demand (BOD) of the test item in the test media was lower than in the inoculum controls. Consequently, the test item was found to be not biodegradable under the test conditions within 28 days.

In the toxicity control, containing both test item at 51 mg/L and the reference item sodium benzoate at 100 mg/L, no inhibitory effect on the biodegradation of the reference item was determined. In the procedure controls, the reference item sodium benzoate was biodegraded by an average of 97% on exposure Day 14, and reached an average biodegradation rate of 96% by the end of the test (Day 28), thus confirming suitability of the activated sludge.

Reference 2

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

from 2004-03-05 to 2004-08-12

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)

Deviations:

yes

Remarks:

- Instead of DOC (COD) measurement, biodegradation was monitored with specific analysis of IPBC and of its degradation product PBC in the aqueous phase and in the activated sludge.

Qualifier:

according to guideline

Guideline:

EU Method C.9 (Biodegradation: Zahn-Wellens Test)

Deviations:

yes

Remarks:

- The ratio between inoculum and test item IPBC (as DOC) was higher than recommended since a relatively high amount of inoculum was needed for the specific analysis and the test item is toxic to activated sludge at concentrations >10 mg/L.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Batch No.: 0306-8715A

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, adapted

Details on inoculum:

- Source of inoculum/activated sludge: wastewater treatment plant treating predominantly domestic wastewater - ARA Ergolz II, Fullinsdorf, Switzerland
- Preparation of inoculum for exposure: incubation for one day under the test conditions
- Pretreatment: washed twice with tap water by centrifugation and the supernatant liquid phase was decanted; aeration at room temperature for three days until use
- Concentration of sludge: 0.9 g dry material per liter
- Initial cell/biomass concentration: inoculum to test item, low dose - 129000 : 1, high dose - 3000 : 1
- Water filtered: no

Duration of test (contact time):

28 d

Initial conc.:

1 mg/L

Based on:

DOC

Remarks:

High dose

Initial conc.:

20 µg/L

Based on:

DOC

Remarks:

Low dose

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: according to testing Guideline
- Additional substrate: not used
- Solubilising agent: not used
- Test temperature: 22 - 25 °C.
- pH: 6.6 - 7.5
- pH adjusted: yes
- Aeration of dilution water: no aeration
- Suspended solids concentration: 0.9 g dry matter /L
- Continuous darkness: yes
- Other: Oxygen concentration: 3.2-8.4 mg O2/L

TEST SYSTEM
- Culturing apparatus: 5000-mL Erlenmeyer flasks filled with 2500 mL test medium, equipped with magnetic stirrers
- Number of culture flasks/concentration: 14 x high dose, 2 x low dose, 2 x procedure control, 2 x inoculum control, 1 x toxicity control
- Test performed in open system: yes, vessels coverd loosely with aluminium foil to allow the exchange of air between the flask and the surrounding atmosphere.

SAMPLING
- Sampling frequency: Low dose: at 0, 2, 4, 8, 24, 48 hours and on day 3; High dose: sampling at 0, 2, 4, 8, 24, 48 hours and on day 3, 7, 14, 21, 28;
- Sampling method: Samples taken at 0, 2, 4,and 8 h: the aqueous phase and the sludge was analysed. Samples taken at 24 hours and later: only the aqueous phase was analysed.
- Sample storage before analysis: analysed directly agter sampling; samples taken after 48 h and on Day 3 and 21 were deep-frozen (- 20 °C) after filtration and analysed on Day 7 and 28, respectively.

CONTROL AND BLANK SYSTEM
- Inoculum blank: inoculum, but no test substance
- Procedure control: inoculum with reference substance; initial concentration 170 mg/L
- Toxicity control: inoculum with test substance and with reference substance

STATISTICAL METHODS: Not relevant, because the results allowed for a conclusive interpretation.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (DOC removal)

Remarks:

Low dose (0.02 mg/L)

Value:

ca. 80

Sampling time:

0 h

Key result

Parameter:

% degradation (DOC removal)

Remarks:

High dose (1 mg/L)

Value:

99

Sampling time:

2 h

Key result

Parameter:

% degradation (DOC removal)

Remarks:

High dose (1 mg/L)

Value:

100

Sampling time:

4 h

Details on results:

After 2 hours, IPBC concentrations of 0.01 (sample 1) and 0.02 mg/L (sample 2) were determined at high dosage in the aqueous phase, corresponding to a degradation of 99%. After 4 hours, no IPBC was detected (LOQ 0.01 mg/L). In the sludge, no IPBC was detected in the sludge (LOQ 0.01 mg/kg).

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable

Conclusions:

Based on the measured concentrations of IPBC and PBC, rapid biodegradation of IPBC to PBC and further biodegradation of PBC was shown. IPBC was almost completely degraded to PBC within 2 hours. PBC was not absorbed to the sludge, it was almost completely dissolved in the aqueous phase.

Executive summary:

A modified Zahn Wellens / EMPS test was conducted according to OECD Guideline 302 B. The biodegradation process was monitored by specific analysis of the test item IPBC and the degradation product PBC in the aqueous phase and in the activated sludge.

Low dose (0.02 mg/L IPBC): IPBC was rapidly degraded in the aqueous phase to PBC. Concerning the sludge no statement could be made to the fate of PBC at the low IPBC concentrations because of analytical interference due to contaminants in the sludge.

High dose (1.0 mg/L IPBC): In the aqueous phase, the IPBC concentrations decreased to 1.5 % and 0.9 % of the nominal values within two hours of incubation. In these samples, 85 % and 89 % of the maximum theoretical amount of the degradation product PBC were detected. The concentration of PBC in the water phase continuously decreased during the test period and was below 0.01 mg/L (LOQ) after 21 days of incubation. No significant amounts of IPBC and IPBC were found in the activated sludge samples.

Description of key information

Under the conditions of an OECD 301F compliant study, the test item is considered to be not readily biodegradable within 28 days.

A modified Zahn Wellens study with the test item revealed based on the measured concentrations of IPBC and PBC a rapid degradation of IPBC to PBC. Further biodegradation of PBC was shown. IPBC was almost completely degraded to PBC within 2 hours. PBC was not absorbed to the sludge, it was almost completely dissolved in the aqueous phase.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable

Additional information

Ready biodegradability

The test item was investigated for its ready biodegradability in a manometric respirometry test over 28 days based on EU Commission Directive 92/69 EEC, C.4 -D (1992) and OECD Guideline for Testing of Chemicals No. 301 F (1992).

Based on the results of the "Respiration Inhibition Test" the test item concentration was reduced in this manometric respirometry test from normally 100 mg/L to about 50 mg/L to avoid a possible inhibitory effect of the test item on the activity of activated sludge microorganisms. This reduced concentration is slightly below the EC20 of test item in the respiration inhibition test (57 mg/L) and is in compliance with the testing guidelines.

The percent biodegradation of the test item was calculated based on the theoretical oxygen demand of 1.03 mg O2/mg test item without nitrification (ThODNm) and 1.25 mg O2/mg test item with nitrification (ThODN03).

The biochemical oxygen demand (BOD) of the test item in the test media was lower than in the inoculum controls. Consequently, the test item was found to be not biodegradable under the test conditions within 28 days.

In the toxicity control, containing both test item at 51 mg/L and the reference item sodium benzoate at 100 mg/L, no inhibitory effect on the biodegradation of the reference item was determined. In the procedure controls, the reference item sodium benzoate was biodegraded by an average of 97% on exposure Day 14, and reached an average biodegradation rate of 96% by the end of the test (Day 28), thus confirming suitability of the activated sludge.

Zahn Wellens Test

A modified Zahn Wellens / EMPS test was conducted according to OECD Guideline 302 B. The biodegradation process was monitored by specific analysis of the test item IPBC and the degradation product PBC in the aqueous phase and in the activated sludge.

Low dose (0.02 mg/L IPBC): IPBC was rapidly degraded in the aqueous phase to PBC. Concerning the sludge no statement could be made to the fate of PBC at the low IPBC concentrations because of analytical interference due to contaminants in the sludge.

High dose (1.0 mg/L IPBC): In the aqueous phase, the IPBC concentrations decreased to 1.5 % and 0.9 % of the nominal values within two hours of incubation. In these samples, 85 % and 89 % of the maximum theoretical amount of the degradation product PBC were detected. The concentration of PBC in the water phase continuously decreased during the test period and was below 0.01 mg/L (LOQ) after 21 days of incubation. No significant amounts of IPBC and IPBC were found in the activated sludge samples.