4-methylstyrene

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

September, 2016 to December, 2016

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Read across study

Justification for type of information:

The study with the read across substance is considered sufficient to fulfil the information requirements.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Nominal and measured concentrations:

Nominal: 0, 90, 170, 310, 560 and 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3.5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC0

Effect conc.:

592 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

170 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Validity criteria fulfilled:

yes

Conclusions:

Under the study conditions, a nominal 3 h EC50 of 592 mg/L based on total oxygen uptake inhibition was found for the test substance. The nominal 3 h NOEC was equivalent to 170 mg/L.

Executive summary:

A study was conducted to determine the effect of the read across substance, vinyl toluene, on the respiration rate of activated sludge according to EU Method C11, in compliance with GLP. Based on the results of a preliminary study, activated sludge from a municipal wastewater treatment plant was exposed to the substance at 5 nominal concentrations ranging from 90 to 1000 mg/L. Six blank controls, three at the beginning and three at the end of the test were also included. 3,5-dichlorophenol was used as a reference substance at 5, 10 and 20 mg/L. Abiotic decomposition was not detected in the preliminary study , therefore no abiotic control was included in the main study. All criteria of acceptability were fulfilled and the study was considered valid. Under the study conditions, a nominal 3 h EC50 of 592 mg/L based on total oxygen uptake inhibition was found for the test substance. The nominal 3 h NOEC was equivalent to 170 mg/L (Nachtigallova, 2016).

Key value for chemical safety assessment

EC50 for microorganisms:

592 mg/L

EC10 or NOEC for microorganisms:

170 mg/L

Additional information

A study was conducted to determine the effect of the read across substance, vinyl toluene, on the respiration rate of activated sludge according to EU Method C11, in compliance with GLP. Based on the results of a preliminary study, activated sludge from a municipal wastewater treatment plant was exposed to the substance at 5 nominal concentrations ranging from 90 to 1000 mg/L. Six blank controls, three at the beginning and three at the end of the test were also included. 3,5-dichlorophenol was used as a reference substance at 5, 10 and 20 mg/L. Abiotic decomposition was not detected in the preliminary study , therefore no abiotic control was included in the main study. All criteria of acceptability were fulfilled and the study was considered valid. Under the study conditions, a nominal 3 h EC50 of 592 mg/L based on total oxygen uptake inhibition was found for the test substance. The nominal 3 h NOEC was equivalent to 170 mg/L (Nachtigallova, 2016).