Diamminediisocyanatozinc

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:

1996-02-05 - 1996-02-22

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

Version / remarks:

OECD Guidelines for.Testing of Chemicals (1984) No. 209 "Activated Sludge Respiration Inhibition Test"

Deviations:

yes

Remarks:

Analysis of the concentration, homogeneity and stability of the test materia! in the test preparations was not appropriate to the Test Guideline.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

EEC Commission Directive 87/302/EEC

Deviations:

yes

Remarks:

Analysis of the concentration, homogeneity and stability of the test materia! in the test preparations was not appropriate to the Test Guideline.

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Amounts of test material (5, 16, 50, 160 and 500 mg) were dispersed together with activated sewage sludge, synthetic sewage and water to a final volume of 500 ml to give the final concentrations of 10, 32, 100, 320 and 1000 mg/l.

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Name and location of sewage treatment plant where inoculum was collected: A mixed population of activated sewage sludge micro-organisms was obtained on 5 February 1996 from the aeration stage of the Severn Trent Water Pic sewage treatment plant at Belper, Derbyshire, UK which treats predominantly domestic sewage.
- Preparation of inoculum for exposure: Preparation of inoculum
The activated sewage sludge sample was fed 50 ml/I synthetic sewage and maintained on continuous aeration in the laboratory at a temperature of 21 °C. The pH of the sample was 7.5 and the suspended solids equal to 4.0 g/l prior to use.

Test type:

static

Water media type:

freshwater

Remarks:

laboratory tap water dechlorinated by passage through an activated carbon filter with a total hardness of approximately 100 mg/l as CaCO3

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

none

Hardness:

total hardness of approximately 100 mg/l as CaCO3

Test temperature:

21°C

Nominal and measured concentrations:

Definitive study: 10, 32, 100, 320 and 1000 mg/l (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 ml conical flask
- Aeration: yes
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: The test water used for both the range-finding and definitive studies was laboratory tap water dechlorinated by passage through an activated carbon filter with a total hardness of approximately 100 mg/l as CaCO3
- Particulate matter:

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Light intensity: The study was conducted under normal laboratory lighting

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : respiratory rate

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.3
- Range finding study
- Test concentrations: nominal test concentrations of 1.0, 10, 100 and 1000 mg/l.
- Results used to determine the conditions for the definitive study: see results

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

180 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Blank controls oxygen uptake rate: 0.48 - 0.52 mg O2/l/min
- Coefficient of variation of oxygen uptake rate in control replicates: Variation in respiration rates of controls 1 and 2 after 3 hours: ± 4%.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: 3,5-dichlorophenol EC50 (3 hours): 9 mg/l

Validity criteria fulfilled:

yes

Conclusions:

The study was conducted under OECD TG 209, the validity criteria are met and is sufficiently documented to conclude that the study was properly performed and so, the results can be considered reliable. The effect of the test item on the respiration of activated sewage sludge microorganisms gave a 3-hour EC50 of 180 mg/l.

Executive summary:

Methods: A study was performed to assess the effect of the test material on the respiration of activated sewage sludge. The method followed that described in the OECD Guidelines for.Testing of Chemicals (1984) No. 209 "Activated Sludge Respiration Inhibition Test" and EEC Commission Directive 87/302/EEC under GLP.

Procedure: The test material was aerated for a period of 3 hours at 21° C in the presence of activated sewage sludge with the addition of a synthetic sewage as a respiratory substrate. The rate of respiration was determined after 30 minutes and 3 hours contact time and compared to data for the control and a reference material, 3,5-dichlorophenol.

Results: The effect of the test material on the respiration of activated sewage sludge gave a 3-Hour EC₅₀ of 180 mg/l.

Description of key information

OECD 209, GLP, activated sewage sludge, respiration inhibition, 3h: 3h EC₅₀ = 180 mg/l

Key value for chemical safety assessment

EC50 for microorganisms:

180 mg/L

EC10 or NOEC for microorganisms:

10 mg/L

Additional information

In the range-finding study, significant inhibition of respiration was observed at 100 and 1000 mg/l, however, there were no significant effects on respiration at 1,0 and 10 mg/l. Based on this information test concentrations of 10, 32, 100, 320 and 1000 mg/l were selected for the main study. Also, this data may indicate a NOEC of 10 mg/L