m-toluidine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: inherent biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1976

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Principles of method if other than guideline:

- batch system (comparable to Zahn-Wellens Test OECD TG 302B)

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Details on inoculum:

- activated sludge was adapted to p-toluidine in laboratory prior to testing
- TS concentration was gradually increased up to 200 mg/l COD during the adaptation period of 20 days
- inoculum concentration applied was 100 mg/l dry matter

Duration of test (contact time):

120 h

Initial conc.:

200 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

other: COD

Parameter:

other: removed COD

Value:

97.7

Sampling time:

5 d

Details on results:

removed COD after 5 days: 97.7%
rate of biodegradation after 5 days: 30.0 mg COD g/h
In a Zahn-Wellens test conducted with adapted inocolum after 5 days 97.7 % of the initial concentration (200 mg/l COD) as the sole source of carbon had been removed (Pitter, 1976).

Validity criteria fulfilled:

not specified

Remarks:

Since the test is poorly reported the validity criteria cannot be assessed sufficiently. Nevertheless the test is considered as valid based on the data given.

Interpretation of results:

inherently biodegradable

Conclusions:

The substance is inheretly biodegradable.

Executive summary:

With a test design comparable to Zahn-Wellens Test OECD TG 302B the inherent biodegradability was determined. The degradation was 97.7 % after 5 days related to COD. Therefore the substance is considered as inherently biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 E (Ready biodegradability: Modified OECD Screening Test)

Principles of method if other than guideline:

Directive 84/449/EEC, C.3; ISO 7824 (1984) (precursor)

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

other: effluent of predominantly domestic STP

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

-replicates per concentration: 2

Reference substance:

aniline

Reference substance:

other: hydroquinone

Parameter:

% degradation (DOC removal)

Value:

64 - 84

Sampling time:

28 d

Details on results:

degradation of m-toluidine (first run)
7 d: - 24 %
14 d: 91 %
21 d: 98 %
28 d: 84 %

degradation of m-toluidine (second run)
7 d: - 24 %
14 d: 83 %
21 d: 91 %
28 d: 64 %

negative values mean an increase of the DOC in the test system compared to the control, no explanation is given for these findings

Results with reference substance:

- degradation of aniline fulfilled the pass level as 86 +/- 10 % (mean value) were degraded after 14 d
- degradation of hydroquinone showed a greater variability, but observed degradation after 14 d reached the pass level

- The report includes results of a multitude of comopounds, whereas only the 
percentage degradation was reported.
- as only these results were provided, where control samples fulfilled the 
validity criteria (stated by the authors), results are assumed to reliable 
- there is no explanation for the decreasing degradation observed after day 21, 
nevertheless observed degradation at day 28 exceeds the pass level of 
70 % degradation
- 10 d window: no specific information is presented, but as no degradation was 
observed on day 7 and 91 % and 83 %, respectively were degraded at day 14, 
the fullfilment of the 10 d window can be assumed

Validity criteria fulfilled:

yes

Remarks:

The pass level was reached within the 10 day window. The reference substance aniline fulfilled the pass level as 86 +/- 10 % (mean value) were degraded after 14 d.

Interpretation of results:

readily biodegradable

Conclusions:

With a degradation of 64 % and 84 % after 28 d the substance is considered as readily biodegradable

Executive summary:

Testing m-toluidine towards ready biodegradability in a modified OECD screening test, 64 % to 84 % of the test item were degraded after 28 d, respectively (Trenel, 1982). Furthermore, the pass level is reached within the 10 day window. Thus, the substance can be scored as readily biodegradable.

Description of key information

With a degradation of 64 % to 84 % after 28 d the substance is considered as readily

biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Testing the substance towards ready biodegradability in a modified OECD screening test, 64 % to 84 % of the test item were degraded after 28 d, respectively. Furthermore, the pass level is reached within the 10 day window. Thus, the substance is considered as readily biodegradable.

With a guideline corresponding to the OECD guideline 301C no degradation was observed within 4 weeks. Though there is evidence that the test item inhibits the inoculum when tested at higher concentrations. As tests were performed testing 100 mg/L, and there is no information with respect to the performance of toxicity controls, no conclusion can be drawn whether the test item is really not biodegradable.

In an inherent biodegradation test the degradation was 97.7 % after 5 days indicating that the substance is inherently biodegradable. The test was performed with a test design comparable to Zahn-Wellens Test OECD TG 302B.

Biodegradation of chemicals (including m-toluidine) was tested under anaerobic conditions in aquifer slurries from a sulfate reducing and a methanogenic site. Degradation of m-toluidine could be detected after eight months, within 10 months 73 % of the test item were biodegraded in the sulfate reducing aquifer slurries, but no degradation could be detected in the methanogenic aquifer slurries.