3-(2,2-dimethyl-3-hydroxypropyl)toluene

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:

2000-07-11

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

no reference substance

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

adopted April 4, 1984

Deviations:

no

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: No stock solutions were prepared, substance was directly weighed into flasks

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: STP Hildesheim, Germany
- Preparation of inoculum for exposure: The sludge was washed twice with autoclaved tap water and diluted corresponding to a dry weight of 3.0 ± 0.6 g/L.

Test type:

static

Water media type:

other: Synthetic waste water according to OECD 209

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20°C

pH:

pH-value of the activated sludge: 7.1

Nominal and measured concentrations:

Nominal concentrations: 10 - 32 - 100 - 320 - 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 mL Erlenmeyer flasks, DIN 12440
- Fill volume: 500 mL
- Aeration: permanent ventilation
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Application: 200 mL inoculum, 16 mL synthetic waste water, 284 mL demineralised water, directly weighing of test item concnetrations
- Dry sludge concentration: 4.6 g/L

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Range finding study : Yes, with 10, 100, 1000 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

170 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other: Confidence interval (P = 95%): 148 - 197 mg/L

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

71 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

409 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

  Respiration rates and inhibition of respiration of test item concentrations 

Concentration [mg/L]	respiration rate [mgO2/L*h]	inhibition [%]
1000	1.4	95
320	6.4	78
100	21.2	25
32	26.8	6
10	27.2	4
Control 1	28.8
Control 2	28.0

Validity criteria fulfilled:

yes

Remarks:

The two control respiration rates differ not more than 15 %.

Conclusions:

This study according to OECD 209 resulted in an EC50 (3h) of 170 mg/L (respiration inhibition).

Description of key information

EC50 (3h) = 170 mg/L based on respiration inhibition (OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:

170 mg/L

Additional information

The available respiration inhibition test with activated sludge from a municipal STP processing mainly domestic sewage was performed in accordance with OECD TG 209. All validity criteria were fulfilled. The substance was tested at nominal concentrations of 10, 32, 100, 320 and 1000 mg/L. The 3-hour EC50 for inhibition of respiration was determined to be 170 mg/L.