4-Butyl-4''-ethyl-2'-fluor-1,1':4',1''-terphenyl

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:

2007-04-30 - 2007-07-03

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

The activated sludge used for this study was washed by centrifugation and the supernatant liquid phase was decanted. The solid material was resuspended in tap water and again centrifuged. This procedure was repeated twice. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 1.5 g dry material per litre were mixed with test water and then aerated until use.

Duration of test (contact time):

28 d

Initial conc.:

102.4 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Temperature: 21.5 - 21.6 °C
Light conditions: darkness
pH: 7.6 (start), 7.6 - 7.8 (end)

The amounts of test item and reference item were directly weighed into the test flasks. No emulsifiers or solvents were used, but the solutions were dispersed by stirring to achieve a homogeneous solution of the test item. The closed test flasks were incubated in a climatized room under continuous stirring.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

3

Sampling time:

28 d

Details on results:

Points of degradation plot (test substance): 3 % degradation after 28 d

Results with reference substance:

The reference item sodium benzoate was sufficiently degraded to 117 % after 14 days, and to 114 % after 28 days of incubation. The percentage biodegradation of the reference item confirms the suitability of the used activated sludge inoculum.

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The test item is not considered to be readily biodegradable.

Executive summary:

 

Purpose

The test item was investigated for its ready biodegradability in a Manometric Respirometry Test over a period of 28 days. The biodegradation was followed by the oxygen uptake of the micro organisms during exposure. As a reference item sodium benzoate was tested simultaneously under the same conditions as the test item, and functioned as a procedure control. The GLP study was performed according to OECD TG 301F.

 

Result

Biodegradation of test item

After correction of the mean biochemical oxygen demand of the inoculum controls at the end of the 28 -day exposure period the degradation of 3 % was found.

 

Biodegradation of Sodium Benzoate

The reference item was sufficiently degraded to a mean of 117 % after 14 days, and to a mean of 114 % after 28 days of incubation, thus confirming the suitability of the used activated sludge inoculum.

 

Biodegradation in the Toxicity Control

In the toxicity control containing both, the test item and the reference item, 42 % biodegradation was noted within 14 days and 44 % biodegradation was determined after 28 days of incubation. Thus, the test item can be assumed to be not inhibitory on the activated sludge micro organisms.

 

Conclusion

The degradation rate of the test material did not reach 60 % within the 10-day window and after 28 days of incubation. Thus the test item is not readily biodegradable.

Description of key information

The information for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 301F. In this study, the test material was not readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater