2,2',6,6'-tetra-tert-butyl-4,4'-methylenediphenol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: EU method C.11. GLP study.

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test organisms (species):

activated sludge

Test type:

static

Water media type:

freshwater

Total exposure duration:

3 h

Test temperature:

20 ºC

pH:

7.3-8.1

Nominal and measured concentrations:

Information supplied with the test substance indicated that its water solubility at 20 ºC was 0.04% (0.4 g/L). However, a nominal 0.25 g test substance/L stock solution only contained 0.4 mg/L in solution (determined by carbon analysis on samples passed through a 0.2 µm membrane filter). Test flasks therefore only contained from 1.5 to 148 µg/L of the test substance.

Reference substance (positive control):

yes

Remarks:

(3,5-dichlorophenol)

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 148 µg/L

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: Higher concentrations could not be tested due to the poor water solubility of the test substance.

Results with reference substance (positive control):

The three hour EC50 for 3,5-dichlorophenol was 6 mg/L (within the accepted range of 5-30 mg/L).

Validity criteria fulfilled:

yes

Remarks:

(the two control respiration rates were within 15% of each other and the three hour EC50 for 3,5-dichlorophenol was within the acceptable range).

Conclusions:

In the EEC activated sludge respiration inhibition test, the test substance was not inhibitory at concentrations up to 148 µg/L after a three hour contact time. Higher concentrations could not be tested due to the poor water solubility of the test substance.

Executive summary:

The aims of this study were to determine any inhibitory effects of the test substance on activated sludge respiration and to assess its "ready biodegradability" using the EEC modified Sturm test. In the EEC activated sludge respiration inhibition test, the test substance was not inhibitory at concentrations up to 148 µg/L after a three hour contact time. Higher concentrations could not be tested due to the poor water solubility of the test substance.

Description of key information

The substance did not inhibit sewage sludge treatment plant organisms up to the maximum test concentration that could be applied in the test system. 

Additional information

A standard respiration inhibition test according to recent guidelines was performed with the test substance up to the maximum attainable concentration. No inhibitory effects on the microorganisms were observed.