Ziram

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 February 1999 - 17 May 1999

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:

1984

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method:
Test substance: a stock dispersion of the test substance was prepared by dispering 0.2010 g of Ziram in 1000 mL of BOD dilution water
Reference substance: a stock solution of the reference substance was prepared according to the OECD guideline by dissolving 0.1251 g in 5 mL NaOH solution, adjusting the pH to 7.7 with HCl solution, and the making up to 250 mL with Nanopure water
- Controls: yes

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Source: oxidation ditch treating domestic sewage, Berkel en Rodenrijs, The Netherlands
- Preparation of inoculum for exposure: the sample was centrifugated and the supernatant discarded. Activated sludge was washed three times by centrifugation (10 min at 2000 rpm = max. 1218 g) and resuspension in tap water twice and in dilution water once. The dry weight of the sludge suspension was determined and the suspension diluted to approximately 4 g/L of mixed liquor suspended solids (MLSS) by addition of dilution water. Then, it was aerated vigorously and kept at approximately 20°C in the dark.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20°C

pH:

7.9

Nominal and measured concentrations:

Nominal concentrations: Negative control, 0.10, 0.32, 1, 3.2, 10, 32 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 1 L glass beakers containing 16 mL of synthetic sewage feed, 284 mL of control (dilution water) or treatment solutions and 200 mL of activated sludge
- Aeration: 0.5 to 1 L/min
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Suspended solids: 4.5 g/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: the dilution water was prepared according to NEN standard No. 6634.
- Synthetic sewage feed was prepared according to OECD guideline

EFFECT PARAMETERS MEASURED: respiration inhibition

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

19.2 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:

NOEC

Effect conc.:

0.32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

The EC50 for 3,5-dichlorophenol was determined to be 13.2 mg/L, value within the validity range of the OECD guideline (5 to 30 mg/L)

Table 1: Validity criteria for OECD 209

Criterion from the guideline	Outcome	Validity criterion fulfilled
The blank controls (without the test substance or reference substance) oxygen uptake rate should not be less than 20 mg oxygen per one gram of activated sludge (dry weight of suspended solids) in an hour.	Respiration rates of the two controls were 20.2 and 21.7 mg O2/g/h	yes
The coefficient of variation of oxygen uptake rate in control replicates should not be more than 30% at the end of definitive test.	Variation was 7%	yes

Validity criteria fulfilled:

yes

Remarks:

For details please refer to field "any other information on results incl. tables"

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

supporting study

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 (Carbon and Ammonium Oxidation))

Version / remarks:

2010

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2008

Qualifier:

according to guideline

Guideline:

ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)

Version / remarks:

2007

GLP compliance:

yes (incl. QA statement)

Remarks:

Hess. Ministerium für Umwelt, Energie, Landwirtschaft und Verbraucherschutz, Wiesbaden, Germany

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

activated sludge of a predominantly domestic sewage

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Nominal and measured concentrations:

Nominal: Control (tap water, synthetic sewage and inoculum), 10, 32, 100, 320, 1000 mg/L

Reference substance (positive control):

yes

Remarks:

3.2, 10 and 32 mg 3,5-Dichlorophenol/L

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

58.8 mg/L

95% CI:

>= 29.7 - <= 106.9

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

187.6 mg/L

95% CI:

>= 100 - <= 371.5

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks:

without nitrification

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

19.8 mg/L

95% CI:

>= 2 - <= 47

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of heterotrophic respiration

Remarks:

without nitrification

Results with reference substance (positive control):

- Results with reference substance valid: yes
- Relevant effect levels: EC50 (3 h) = 4 mg/L (total respiration), EC50 (3 h) = 15.5 mg/L (heterotrophic respiration without nitrification)

The oxygen uptake in the blank controls was 28.5 mg/g/h and therefore clearly above 20 mg oxygen/g of activated sludge (dry weight of suspended solids) in an hour. The respiration rates of the six controls differed not more than 30 %. The value was 10.0 % for the total respiration and 9.9 % for the heterotrophic respiration. These validity criterions were fulfilled.

Validity criteria fulfilled:

yes

Remarks:

For details please refer to field "any other information on results incl. tables"

Description of key information

EC50 (3 h) = 19.2 mg/L (nominal, activated sludge, OECD 209)

NOEC (3 h) = 0.32 mg/L (nominal, activated sludge, OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:

19.2 mg/L

EC10 or NOEC for microorganisms:

0.32 mg/L

Additional information

Two studies are available assessing the toxicity of zinc bis dimethyldithiocarbamate (CAS No. 137-30-4) towards aquatic microorganisms.

In the key study (1999) the effect of the substance on aquatic microorganisms activity was investigated according to the OECD Guideline No. 209 and GLP. Activated sludge of a predominantly domestic sewage was exposed for 3 h to the test item concentrations of 0.10, 0.32, 1, 3.2, 10, 32 and 100 mg/L and a negative control. The inhibition of total respiration rate was measured, resulting in an EC50 (3 h) value of 19.2 mg/L (nominal). This study was chosen as key study due to its methodological reliability and due to the most sensitive effect values.

In the supporting study (2014) the effects of the substance on sewage sludge microorganisms were assessed according to the OECD Guideline No. 209 and GLP. The activated sludge of a predominantly domestic sewage was exposure for 3 h to 10, 32, 100, 320 and 1000 mg test item/L and the respiration rate (oxygen consumption) was measured. The 3-hour EC50 was 58.8 mg/L (nominal, inhibition of total respiration). For heterotrophic respiration without nitrification the 3-hour EC50 was 187.6 mg/L (nominal).