(xylenes and 4-ethylbenzene)sulfonic acids

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

Study period:

1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Similar to Guideline but some test condition details missing

Justification for type of information:

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

not specified

Analytical monitoring:

no

Details on sampling:

- Concentrations: 100, 180, 320, 580, 1000 mg/L

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Pretreatment: After 2nd sedimentation, washed with tap dechlorinated water
- Initial biomass concentration: 2 g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

21C

Nominal and measured concentrations:

nominal - 100, 180, 320, 580, 1000 mg/L

Details on test conditions:

no data

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

240 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

580 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth inhibition

Details on results:

3h EC10 ca 240 mg/L
3h EC20 ca 650 mg/L
3h EC30 ca >1000 mg/L
3h EC80 ca >1000 mg/L

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 47% inhibition at 60 mg/L

Reported statistics and error estimates:

Statistical Method - Ausgewahite Methoden der Wasseruntersuchung, part 2, p 379-382, VEB Fisher Verlang
EC determinations made using probability grid

Test Concentration - Control #1, Control #2, Positive Control, and 100, 180, 320, 580, 1000 mg/L

Respiratory Rate (mg O2/L/h) - 29.2, 33.6, 16.8, 28.8, 28.4, 28.4, 27.6, 23.2

Inhibition (%) - 0, 0, 47, 8, 10, 10, 12, 26

Validity criteria fulfilled:

yes

Conclusions:

The 3h EC10 for the test substance was 240 mg/L which is equivalent to 156 mg/L active substance. The NOEC based on growth inhibition was 580 mg/L which is equivalent to 377 mg/L active substance.

Description of key information

There is a single study of microbial toxicity; a 1989 bacteria toxicity test with activated sludge microbes. The 3-hour NOEC for growth inhibition is 580 mg/L.  

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

580 mg/L