zinc glycyniate

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:

2019

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test organisms (species):

activated sludge of a predominantly domestic sewage

Total exposure duration:

3 h

Remarks on exposure duration:

contact time 3 hours, during which aeration takes place

Test temperature:

20 ± 2°C

Details on test conditions:

Duration: contact time 3 hours, during which aeration takes place
Air supply: clean, oil-free air. Air flow 0.5 to 1 litre/minute
Nutrient solution: synthetic sewage feed
Test item concentrations:: 0.10, 1.0, 10.0, 100.0 and 1000.0 mg/l
Reference item concentrations: 0.01 , 0.1, 1.0 , 10.0 and 100.0 mg/l
Blank controls: Inoculated sample without test substance
Temperature: 20 ± 2°C
Test item stock solutions 10 g/l (at pH = 7.0) (no undissolved particles were
observed)
Reference substance stock solutions 1 g/l
Synthetic medium stock solution: See p. 3.1.4
Activated sludge stock suspension: 3 g/l of suspended solids
Activated sludge suspension in test vessels 1.5 g/l of suspended solids
ATU stock solution 2.32 g/l

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

109 mg/L

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

158.6 mg/L

Basis for effect:

inhibition of heterotrophic respiration

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

57.3 mg/L

Basis for effect:

inhibition of nitrification rate

Details on results:

The following test item end points ECX (mg/l) were calculated (eq. 5.2.2.2) for total, heterotrophic and
nitrification inhibition.
ECx, mg/l
Inhibition, % EC20 EC50 EC90
Total 75.1 109.0 175.6
Heterotrophic 123.6 158.6 282.8
Nitrification < 0.1 57.3 247.3
The lowest tested concentration that causes the observed respiration inhibition is equal to 0.1 mg/l.

Validity criteria fulfilled:

yes

Conclusions:

calculated values of the end points EC50 for the test item were found to be:
1. Total respiration inhibition: 109.0 mg/l.
2. Heterotrophic respiration inhibition: 158.6 mg/l.
3. Nitrification inhibition: 57.3 mg/l .

Key value for chemical safety assessment

EC50 for microorganisms:

109 mg/L