Benzene, mono-C10-13-alkyl derivs., distn. residues, sulfonated, barium salts

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study. Responsibility of the study data lies on the master dossier for the main read-across substance. The original study was not handed out.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes

Remarks:

No details available.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material: No details on analogue material available.

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

Activated sludge bacteria from domestic sewage treatment plant used at about 1 drop sludge filterate inoculum basal medium.

Duration of test (contact time):

28 d

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: COD

Details on study design:

Duplicate test vessels were used for the test substance, positive control and control blank. Test vessels were incubated at 20 +/- 1 °C.

Reference substance:

benzoic acid, sodium salt

Reference substance:

aniline

Preliminary study:

Not applicable.

Test performance:

The positive controls were degraded by > 60 % within 28 days.

Parameter:

other: COD

Value:

8

Sampling time:

28 d

Results with reference substance:

Sodium benzoate 97 % after 28 days; aniline 61 % after 28 days.

Validity criteria fulfilled:

yes

Remarks:

Both the reference substances achieved greater or equal to 60% degradation, and therefore, the test was valid.

Interpretation of results:

other: Only limited biodegradation observed (8 %/28 d)

Conclusions:

The report describes a valid guideline study with GLP compliance. The substance is not readily biodegradable, achieving 8 % degradation over 28 days. The substance CAS 70024-69-0 is therefore considered to be persistent, but the small amount of biodegradation suggests the substance is not unduly toxic to sewage sludge.

Executive summary:

A 28 day aerobic ready biodegradability study, which was conducted according to OECD Guideline 301D was conducted using an initial substance concentration of 2 mg/L. The effects of the test substance (CAS 70024 -69 -0) were assessed based on chemical oxygen demand (COD) measurements using activated sludge from a domestic wastewater plant as inoculum. No pre-adaption was performed. The COD was determined using the Hach semi-micro sample digestion methods followed by direct reading using a Hach DR/2 Spectrometer. Each vessel was incubated twice, the temperature was held constant at 20 +/- 1 °C. For evaluation, sodium benzoate and aniline were used as reference substances, which attained 97 % and 61 % degradation after the incubation period of 28 days, respectively. The experiment can be considered as valid. At the end of the exposure period, the test substance attained 8 % degradation. It can be concluded that the test substance (CAS 70024 -69 -0) is not readily biodegradable.

Description of key information

RA_CAS 70024-69-0, OECD 301D: 8 % degradation after 28 days (Douglas, 1989). Therefore, the read-across substance is not readily biodegradable.      

RA_CAS 61789-86-4, OECD 301F: 8.6 % degradation after 28 days (Sanitised, O. 1996). Therefore, the read-across substance is not readily biodegradable.

RA_CAS 68783-96-0, OECD 301B: 9.1 % degradation after 28 days (Sanitised, P., 1995). Therefore, the read-across substance is not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Calcium sulfonate read-across substance (CAS 70024-69-0) attained 8 % degradation during the test duration of 28 days (OECD Guideline 301D, Douglas, 1989). With regard to the supporting studies, Sanitised, O. (1996) determined 8.6 % degradation after 28 days (OECD Guideline 301F) for the calcium sulfonate read-across substance (CAS 61789 -86 -4) while 9.1 % degradation was attained for the calcium sulfonate read-across substance (CAS 68783-96-0) after 28 days (OECD Guideline 301B, Sanitised, P., 1995).

Based on the results of this study, the barium sulfonate target substance (Benzene, mono-C10 -13 -alkyl derivs., distn. residues, sulfonated, barium salts) is not expected to be readily biodegradable.