2-chlorotoluene

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:

1990-10-11 to 1990-11-08

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

Council Directive 79/831/EEC of 18 September 1979 amending for the sixth time Directive 67/548/EEC

Qualifier:

equivalent or similar to guideline

Guideline:

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

Version / remarks:

1992

Principles of method if other than guideline:

Method: Directive EEC 79/831 corresponding to OECD Guideline 301 F

GLP compliance:

yes

Specific details on test material used for the study:

Purity not specified, however analytical grade may be assumed (originating from Bayer AG)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, adapted

Remarks:

Due to the assumed poor biodegradability of the test item, inoculum from a preceding Zahn-Wellens test on inherent biodegradability (Bayer study number 186 A/90 Z, 1991) was used.

Details on inoculum:

Due to the assumed poor biodegradability of the test item, inoculum from a preceding Zahn-Wellens test on inherent biodegradability (Bayer study number 186 A/90 Z, 1991) was used. This does not invalidate the test because the (negative) result definitely demonstrates failure of ready biodegradability for 2-chlorotoluene.
Sampling date: 1990-10-11

Origin of inoculum used for the preceding Zahn-Wellens test:
"Beckenbiologie Nr. 1", common sewage works Bürrig, Bayer AG - Leverkusen

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Remarks:

ThOD: 2149 mg/g

Details on study design:

Inoculum concentration used: 30 mg/L sludge solids;

Replicates: 1

The experimental procedure was according to standard operation procedures (SOPs) No. 0.001, 0.009, 0.017, 1.001, 1.004, 1.007, and 3.003.

Reference substance:

aniline

Preliminary study:

Yes, a Zahn-Wellens test was performed beforehand (Bayer AG, 1991; report No. 186 A/90 Z).

Key result

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

Please see attached illustration for details.

Results with reference substance:

Aniline was degraded by 68% within 28 days.

Validity criteria fulfilled:

not specified

Remarks:

Oxygen consumption of inoculum blank <60 mg/L (fulfilled); pH value not reported. Neither replicates nor a toxicity control have been tested.

Interpretation of results:

not readily biodegradable

Conclusions:

Not readily biodegradable (GLP test similar / equivalent to OECD TG 301F)

Executive summary:

2-Chlorotoluene was tested for ready biodegradability under facilitated conditions, i.e. using activated sludge from a preceding test on inherent biodegradability (Zahn-Wellens test, OECD TG 302B; Bayer AG, 1991). The test was performed compliant with GLP similar / equivalent to OECD TG 301F (Manometric Respirometry). The design of the test (closed respirometer flasks) took due account of the volatile nature of the test item. The result for reference substance aniline (68% after 28 days, >60% after 8 days) confirmed the activity of the inoculum. At a test item concentration of 100 mg/L no biodegradation was observed for 2-chlorotoluene within the duration of the test (0% within 28 days). Considering the adapted inoculum, the test item must be considered to be not readily biodegradable with high confidence.

Description of key information

Not readily biodegradable (GLP test similar / equivalent to OECD TG 301F)

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater

Additional information

An initial (supporting) study on inherent biodegradation performed compliant with GLP similar to the Zahn-Wellens-Test (OECD TG 302B) obtained an elimination of 86 % within 28 days. As significant amounts were eliminated (64 %) within the first 3 h after test start, it is assumed that the elimination predominantly occurred by stripping (volatile nature of 2-chlorotoluene) or adsorption rather than by degradation. Based on the thorough degradation of the reference substance aniline the test is valid.

Considering the volatility as well as the anticipated poor biodegradability of 2-chlorotoluene, the valid key study on ready biodegradability was performed using inoculum from the preceding Zahn-Wellens-Test, i.e. pre-exposed to the test item. Accordingly, 2-chlorotoluene was tested for ready biodegradability under facilitated conditions. The test was performed compliant with GLP similar / equivalent to OECD TG 301F (Manometric Respirometry). The design of the test (closed respirometer flasks) took due account of the volatile nature of the test item. The result for reference substance aniline (68% after 28 days, >60% after 8 days) confirmed the activity of the inoculum. At a test item concentration of 100 mg/L no biodegradation was observed for 2-chlorotoluene within the duration of the test (0% within 28 days). Considering the adapted inoculum and its confirmed activity (reference substance aniline), the test item must be considered to be not readily biodegradable with high confidence.

No other relevant data on biodegradability are available for 2-chlorotoluene.