Dialuminium zinc tetraoxide

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:

06 Feb - 23 Feb 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

The temperature in the pre-test was in a range of 16.9 - 18.8 °C instead of 20 ± 2 °C as recommeded by the guideline.

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Mainz

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Pretreatment: Upon arrival in the test facility, the sludge was filtrated, washed with tap water and resuspended in tap water. The activated sludge was aerated until usage in the test and fed daily with 50 mL/L synthetic sewage feed. On the day before the experiment, the inoculum was taken from its source, washed, aerated and the dry matter was determined. The volume was adapted to the desired content of dry matter. The nutrient solution was thawed and the sludge was fed with 50 mL/L sludge
- Dry matter of sludge: 2.50 g suspended solids/L
- Dry matter in the test: 1.25 g suspended solids/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

1.08 mmol/L

Test temperature:

16.9 - 18.8 °C

pH:

7.7 - 7.8

Nominal and measured concentrations:

nominal: 0, 1.2, 12.2, 100, 999.4, 1000 and 1001.2 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, fill volume: glass beaker, 1000 mL, fill volume: 500 mL
- Aeration: purified air, using Pasteur pipettes, flow approx. 0.75 L/min
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 6
- Biomass loading rate: 1.25 g suspended solids/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised tap water
- Total organic carbon: 0.5 mg/L
- Pesticides: < limit of detection
- Chloride: 12.0 mg/L
- Ca: 35.7 mg/L
- Mg: 0.007 mg/L
- Conductivity: 223 µS/cm

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : respiration rate, at the end of the test

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 8 to 10

Reference substance (positive control):

yes

Remarks:

3,5-Dichloro-phenole

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 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:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

No statistically significant inhibition of respiration was observed at any of the treatments.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 of 8.1 mg/L

Description of key information

NOEC >= 1000 mg/L (activated sludge, OECD 209)

Additional information

One study on the toxicity of Zinc aluminium oxide to microorganisms is available. This key study was performed as a limit test according to OECD Guideline 209, using activated sludge as inoculum (2012). The sludge was exposed to nominal concentrations of 0 (control), 1.2, 12.2, 100, 999.4, 1000 and 1001.2 mg/L during 3 hours. As no significant inhibition was observed in any of the treatments, the NOEC was determined to be 1000 mg/L and the EC50 > 1000 mg/L.