1,3,3-trimethyl-2-[[methyl(p-tolyl)hydrazono]methyl]-3H-indolium chloride

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

other: experimental result from similar substance

Adequacy of study:

key study

Study period:

1993-10-11 to 1993-10-18

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Sufficiently well documented study according to OECD 209 and under GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

BY29 - similar substance 01

IUPAC Name:

BY29 - similar substance 01

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

Concentration: 10, 32, 100, 320, 1000 mg/L

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Microbial source: activated sludge from a water treatment works treating mainly domestic sewage (date of sludge batch: 11.10.1993, date of test: 13.10.1993)- Temperature: 20.1 °C- Water: dechlorinated mains water- Preparation of inoculum for exposure: The sludge is allowed to settle and the supernatant liquor decanted. When the sludge is not used immediately, and for a period up to a maximum of four days, it is maintained aerated at a temperature of 20°C using an incubator. Synthetic sewage feed solution is added at the end of each working day. - Pretreatment: Before the start of the test the solids content of the sludge is determined and a suspension prepared containig 4 g solid per litre. The test beakers are prepared containing synthetic sludge feed. The appropriate volume of stock solution, and dilution water to a final volume of 300 mL. A volume of 200 mL diluted sludge is then added, the beaker placed in the water bath and aerated continuously at a constant rate for the duration of the test. Aeration of the test beakers is started at suitable time intervals, to allow for the oxygen measurement.- Initial biomass concentration: not reported, normalized to 4 g d.w./L

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 min

Post exposure observation period:

10 min, for measurement of dissolved oxygen concentration

Test conditions

Test temperature:

20.1 °C

Dissolved oxygen:

4.65 mg/L to 8.40 mg/L (initial)

Nominal and measured concentrations:

Concentration (nominal): 10, 32, 100, 320, 1000 mg/L

Details on test conditions:

TEST SYSTEM- Test vessel: 1-L beakers/BOD bottles- Type: open - Material: glass, 500 mL- Aeration: yes- No. of vessels per control (replicates): 2- Biomass loading rate: not reported, normalized to 4 g d.w./LTEST MEDIUM / WATER PARAMETERS- Source/preparation of dilution water: dechlorinated mains water- Total organic carbon:- Particulate matter: 4 g d.w./L

Reference substance (positive control):

yes

Remarks:

3,5 dichlorophenol

Results and discussion

Effect concentrations

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

59 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The results of this study show that the test item caused a significant inhibitory effect on the respiration rate of activated sludge after a contact period of 30 min. The estimated EC50 value was 59 mg/L.

Results with reference substance (positive control):

EC50 (3 h) 21 mg/L

Any other information on results incl. tables

Table 1: Respiration rates of activated sludge exposed to the test item. Contact time 30 min

Concentration of sample (mg/L)	Respiration rate (mg O2/L h)	Inhibition (%)
0	mean 31.4	-
10	24.4	22.1
32	19.4	38.3
100	12.0	61.7
320	7.9	74.9
1000	3.7	88.3

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 30 min EC50 value for the test item is determined to be 59 mg/L.

Executive summary:

To investigate potential harmful effects of the test item on environmentally important microorganisms, a study according to OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test) was performed under GLP. When exposed to the test substance at concentrations of 10, 32, 100, 320, 1000 mg/L, the activated sludge exhibited significantly lower respiration rates. The EC50 after 30 min was determined to be 59 mg/L.