Bis(methylcyclohexyl) phthalate

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:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Analytical purity: Mixture of isomers: sum 100.00 area-%
- Lot/batch No.: KN53200656
- Expiration date of the lot/batch: 18 Nov 2017

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Direct addition by initial weight into the test flasks. The test substance was weighed in the required amounts for the test concentrations directly to the testvessels.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

After arrival of the activated sludge suspension in the test facility the suspension was sieved with a fine woven mesh (mesh size about 1 mm). This suspension was pre-aerated over night at room temperature. At the next day the sludge suspension was washed once with drinking water and the suspension was adjusted to 3 g/L Dw.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.9 - 21.9 °C

pH:

7.8 - 7.9

Nominal and measured concentrations:

Nominal: 62.5, 125, 250, 500 and 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1L glass beakers with 500 mL test solution
- Aeration: Oxygen concentration during aeration: > 2 mg/L
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- Sludge concentration (weight of dry solids per volume): 1.5 g/L dw

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: drinking water

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 = 6.3 mg/L
- Other: The EC50 of the reference substance 3,5-dichlorophenol was in the range of 2-25 mg/L in 3 hours.

Validity criteria fulfilled:

yes

Conclusions:

The substance is not harmful to aquatic microorganisms.

Description of key information

No toxicity up to the highest concentration tested (3h-EC10 > 1000 mg/L (nominal) for respiration inhibition of activated sludge (OECD 209))

Additional information

One study investigating the toxicity of the test substance to aquatic microorganisms is available. The study was performed under GLP according to OECD guideline 209 using non-adapted activated sludge from a municipal STP as test organism (BASF 2017). Test substance concentrations between 62.5 and 1000 mg/L were tested. No respiration inhibition was observed in the control and any treatment after an incubation time of 3h. Thus, the 3h-EC10 value is considered to be > 1000 mg/L based on nominal concentrations.