Indole

Biodegradation in soil

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in soil, other

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Justification for type of information:

Data is from peer reviewed journal and authoritative databases

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Biodegradation study was conducted for evaluating the degradability of the test chemical in soil.

GLP compliance:

not specified

Test type:

laboratory

Radiolabelling:

no

Oxygen conditions:

anaerobic

Soil classification:

not specified

Details on soil characteristics:

Organic soil (Carlisle muck) was obtained from State College, Pa.

Soil No.:

#1

Duration:

75 d

Soil No.:

#1

Initial conc.:

> 32 - < 50 other: mg/l

Based on:

test mat.

Parameter followed for biodegradation estimation:

test mat. analysis

Soil No.:

#1

Temp.:

22°C

Details on experimental conditions:

EXPERIMENTAL DESIGN
- Soil condition: fresh
- No. of replication controls, if used: Triplicates
- No. of replication treatments: Triplicates
- Test apparatus (Type/material/volume): Serum bottles of 160 ml volume was used as a test vessel.
- If no traps were used, is the system closed/open: yes, test vessel was closed with butyl rubber stoppers and aluminum crimp seals.

Test material application
- Volume of test solution used/treatment: 100 ml
- Application method (e.g. applied on surface, homogeneous mixing etc.):
- Is the co-solvent evaporated: Organic soil were diluted with media, stirred vigorously, and dispensed as slurries to N2-flushed serum bottles (160 ml).

Experimental conditions (in addition to defined fields)
- Composition of medium: Mineral salt medium was used as a test medium for the study.
- Additional substrate: 1.2 mg of Na2HCO3 and 0.12 mg of Na2S 9H20 per ml were added as an additional substrate in the test medium.
- Test temperature: 22°C
- pH: 7.0
- pH adjusted: yes, pH was adjusted with a solution of HCl.
- Continuous darkness: yes
- Other: After test medium has been autoclaved for 15 min to remove 02, the medium was maintained under a positive pressure of N2 gas which was previously passed through copper filings at 300°C to remove traces of O2. Test chemical was added to the medium when the medium temperature had cooled to 50°C.

Remarks on result:

other: Details not known

Key result

Soil No.:

#1

% Degr.:

100

Parameter:

test mat. analysis

Remarks:

(% degradation)

Sampling time:

67 d

Remarks on result:

other: Other details not known

Key result

Remarks on result:

other: Details not known

Transformation products:

yes

No.:

#1

Details on transformation products:

- Formation and decline of each transformation product during test: Oxindole was formed as one of the product of test chemical which gradually degraded during the study.

Evaporation of parent compound:

not specified

Volatile metabolites:

not specified

Residues:

not specified

Conclusions:

The percentage degradation of test chemical was determined to be 100% after a period of 67 days. Oxindole was formed as one of the product of test chemical which gradually degraded during the study.

Executive summary:

Biodegradation study in soil was conducted for a period of 75 days under anaerobic conditions for evaluating the degradability of the test chemical in organic soil.Organic soil (Carlisle muck) was obtained from State College, Pa. Test chemical concentration used for the study was in the range of 32 to 50 mg/l (0.27 to 0.43 mmol/l). Serum bottles of 160 ml volume was used as a test vessel. Test vessel was closed with butyl rubber stoppers and aluminum crimp seals. Mineral salt medium was used as a test medium for the study. 1.2 mg of Na2HCO3 and 0.12 mg of Na2S 9H20 per ml were added as an additional substrate in the test medium. After test medium has been autoclaved for 15 min to remove 02, the medium was maintained under a positive pressure of N2 gas which was previously passed through copper filings at 300°C to remove traces of O2. Organic soil were diluted with media, stirred vigorously, and dispensed as slurries to N2-flushed serum bottles (160 ml). Test chemical was added to the medium when the medium temperature had cooled to 50°C. The pH of the medium was 7.0 which was adjusted with a solution of HCl. Later, 100 ml portions of inoculated medium were dispensed to N2-flushed serum bottles. Control bottles were sterilized by being autoclaved on three successive days. All bottles were incubated stationary in the dark at a temperature of 22°C for a period of 35 days. All experiments were performed in triplicates, Additional bottles were frozen after various time intervals for subsequent chemical analysis. The disappearance of test chemical in test sludge was monitored by HPLC. The percentage degradation of test chemical was determined to be 100% after a period of 67 days. Oxindole was formed as one of the product of test chemical which gradually degraded during the study. This, indicates that test chemical is not persistent in soil and the exposure to soil dwelling animals is moderate to low.

Description of key information

Biodegradation study in soil was conducted for a period of 75 days under anaerobic conditions for evaluating the degradability of the test chemical in organic soil (from peer reviewed journal (E. L. Madsen et. al., 1988) and authoritative databases). Organic soil (Carlisle muck) was obtained from State College, Pa. Test chemical concentration used for the study was in the range of 32 to 50 mg/l (0.27 to 0.43 mmol/l). Serum bottles of 160 ml volume was used as a test vessel. Test vessel was closed with butyl rubber stoppers and aluminum crimp seals. Mineral salt medium was used as a test medium for the study. 1.2 mg of Na2HCO3 and 0.12 mg of Na2S 9H20 per ml were added as an additional substrate in the test medium. After test medium has been autoclaved for 15 min to remove 02, the medium was maintained under a positive pressure of N2 gas which was previously passed through copper filings at 300°C to remove traces of O2. Organic soil were diluted with media, stirred vigorously, and dispensed as slurries to N2-flushed serum bottles (160 ml). Test chemical was added to the medium when the medium temperature had cooled to 50°C. The pH of the medium was 7.0 which was adjusted with a solution of HCl. Later, 100 ml portions of inoculated medium were dispensed to N2-flushed serum bottles. Control bottles were sterilized by being autoclaved on three successive days. All bottles were incubated stationary in the dark at a temperature of 22°C for a period of 35 days. All experiments were performed in triplicates, Additional bottles were frozen after various time intervals for subsequent chemical analysis. The disappearance of test chemical in test sludge was monitored by HPLC. The percentage degradation of test chemical was determined to be 100% after a period of 67 days. Oxindole was formed as one of the product of test chemical which gradually degraded during the study. This, indicates that test chemical is not persistent in soil and the exposure to soil dwelling animals is moderate to low.

Additional information

Experimental study and predicted data of the test chemical were reviewed for the biodegradation in soil end point which are summarized as below:

 

In an experimental study from peer reviewed journal (E. L. Madsen et. al., 1988) and authoritative databases,biodegradation study in soil was conducted for a period of 75 days under anaerobic conditions for evaluating the degradability of the test chemical in organic soil. Organic soil (Carlisle muck) was obtained from State College, Pa. Test chemical concentration used for the study was in the range of 32 to 50 mg/l (0.27 to 0.43 mmol/l). Serum bottles of 160 ml volume was used as a test vessel. Test vessel was closed with butyl rubber stoppers and aluminum crimp seals. Mineral salt medium was used as a test medium for the study. 1.2 mg of Na2HCO3 and 0.12 mg of Na2S 9H20 per ml were added as an additional substrate in the test medium. After test medium has been autoclaved for 15 min to remove 02, the medium was maintained under a positive pressure of N2 gas which was previously passed through copper filings at 300°C to remove traces of O2. Organic soil were diluted with media, stirred vigorously, and dispensed as slurries to N2-flushed serum bottles (160 ml). Test chemical was added to the medium when the medium temperature had cooled to 50°C. The pH of the medium was 7.0 which was adjusted with a solution of HCl. Later, 100 ml portions of inoculated medium were dispensed to N2-flushed serum bottles. Control bottles were sterilized by being autoclaved on three successive days. All bottles were incubated stationary in the dark at a temperature of 22°C for a period of 35 days. All experiments were performed in triplicates, Additional bottles were frozen after various time intervals for subsequent chemical analysis. The disappearance of test chemical in test sludge was monitored by HPLC. The percentage degradation of test chemical was determined to be 100% after a period of 67 days. Oxindole was formed as one of the product of test chemical which gradually degraded during the study. This, indicates that test chemical is not persistent in soil and the exposure to soil dwelling animals is moderate to low.

 

For the test chemical, the half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database. If released into the environment, 74.3% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 30 days (720 hrs). Based on this half-life value of test chemical, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

 

Thus, on the basis of this available information, test chemical was considered to be not persistent in soil.

 

In addition to this, biodegradation in soil endpoint can also be considered for waiver as per in accordance with column 2 of Annex IX of the REACH regulation, testing for this end point is scientifically not necessary and does not need to be conducted since the test chemical is readily biodegradable in water.