polymeric zinc propylenebis(dithiocarbamate);propineb (ISO)

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:

2009/12/07 to 2009/12/17

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Details on sampling:

To measure the oxygen consumption, 250 mL of sludge with test item (or control or reference compound) was incubated for 3 h in 300 mL closed Erlenmeyer flasks (with air inlet and outlet) and aerated through a glass tube at 50-100 L/h with clean oil-free air. For measurement, the content of the Erlenmeyer flasks was completely transferred to 250 mL BOD bottles and O2-content was measured with an O2-meter (redox electrode) with writer.

The respiration rate for each concentration was determined graphically from the linear part of the curve of O2-content versus time. The inhibitory effect of the test item at a particular concentration is expressed as a percentage of the mean of the respiration rates of two controls. An EC50 value was calculated from the respiration rates at different test item concentrations.

Details on test solutions:

10 mL of sludge suspension were dried in order to calculate the amount of sludge suspension to achieve a concentration of activated sludge of 2 g/L (dry weight) suspended solids. The calculated amount of sludge suspension was taken and filled up to a defined end volume with deionised water.

Test organisms (species):

activated sludge

Details on inoculum:

Type : mixed population of aquatic microorganisms (activated sludge)
Origin : aeration tank of a domestic sewage treatment plant

Test type:

static

Water media type:

other: deionised water

Limit test:

no

Total exposure duration:

3 h

Test temperature:

19.4 - 19.8°C

pH:

7.9 - 8.0

Dissolved oxygen:

2.5 - 6.4 mg O2/L

Nominal and measured concentrations:

Nominal concentrations: 100, 180, 320, 560 and 1000 mg a.s./L

Details on test conditions:

The respiration rate of each mixture was determined after aeration periods of 3 hours. Two controls without test item were included in the test design, one at the start and the other at the end of the test series.
The pH was measured and adjusted to pH 6-8. 8 mL of the synthetic medium and 100 mL of activated sludge were added to the dissolved test item. The mixture was filled up with deionised water to 250 mL and aerated at 20°C ± 2°C. The exposure medium with the reference substance was prepared by adding 8 mL of the synthetic medium, 100 mL of activated sludge and a defined amount of the stock solution to achieve the test concentrations and was filled up to 250 mL with deionised water.

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC10

Effect conc.:

404.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Key result

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

Details on results:

Propineb showed 17.8 % respiration inhibition of activated sludge at a test item concentration of 1000 mg a.s./L.

Results with reference substance (positive control):

The EC50 of the reference compound 3,5-Dichlorophenol is in the range 5 – 30 mg/L.

 

 

Table 1

Oxygen content, temperature and pH-values during exposure phase (test item)

	Test item concentration [mg/L]	O2 start [mg O2/L]	O2 end [mg O2/L]	Time (startend) [min.]	Temp. [°C]	pH
Test item	100	5.6	2.7	5	19.6	7.9
	180	5.8	2.5	6	19.6	7.9
	320	6.4	2.7	7	19.8	8.0
	560	6.5	2.7	8	19.7	8.0
	1000	6.2	2.9	7	19.7	7.9
control 1		6.1	3.2	5	19.4	7.9
control 2		6.4	3.0	6	19.5	7.9
Physicochemical oxygen consumption control *		8.8	8.8	8	19.1	7.3

Comments: * Data obtained in the range finding test.
The test item was added to about 130 mL deionized water and stirred overnight before testing (equilibration phase).
Start of stirring period of the test item: 3 p.m., 2009-12-09
End of stirring period of the test item: 7 a.m., 2009-12-10

 

 

 

Table 2

Results of test item Propineb

Test item concentration (nominal) [mg/L]	Respiratory rate test item [mg/L x h)	Phys.-chem. O2 consumption [mg/L x h]	Respiratory rate - phys.-chem. O2 consumption [mg/L x h]	Inhibition  [%]
100	34.8	0.0	34.8	0.0
180	33.0	0.0	33.0	4.1
320	31.7	0.0	31.7	7.8
560	28.5	0.0	28.5	17.2
1000*	28.3	0.0	28.3	17.8
Control mean	34.4	-	-	-
Control 1	34.8	-	-	-
Control 2	34.0	-	-	-

Comments: Test concentrations are given as nominal concentrations as they were not confirmed by analytical methods.

* The physico-chemical oxygen consumption has been determined at 1000 mg/L test item concentration. As no physico-chemical oxygen consumption was observed at that test item concentration this observation also holds true for the lower test item concentrations.

Validity criteria fulfilled:

yes

Conclusions:

The activated sludge was exposed to propineb at nominal concentrations of 100, 180, 320, 560 and 1000 mg a.s./L. The respiration rate of each mixture was determined after aeration periods of 3 hours. All validity criteria of the test method were met. The EC50 was determined to be >1000 mg a.s./L. Propineb showed 17.8% respiration inhibition of activated sludge at the highest test concentration of 1000 mg a.s./L.

Executive summary:

A study was performed to assess the toxicity of Propineb to bacteria. The study was conducted in accordance with Council Regulation (EC) No 440/2008, Method C.11 ”Activated sludge respiration inhibition” (2008). This test method is equal to OECD Guideline 209 (1984). The activated sludge was exposed to propineb atnominal concentrations of 100, 180, 320, 560 and 1000 mg a.s./L. The respiration rate of each mixture was determined after aeration periods of 3 hours. Two controls without test item were included in the test design, one at the start and the other at the end of the test series. Propineb showed 17.8 % respiration inhibition of activated sludge at the highest test concentration of 1000 mg a.s./L. The EC₅₀ was determined to be >1000 mg a.s./L.

Description of key information

The activated sludge was exposed to propineb at nominal concentrations of 100, 180, 320, 560 and 1000 mg a.s./L. The respiration rate of each mixture was determined after aeration periods of 3 hours. All validity criteria of the test method were met. The EC₅₀ was determined to be >1000 mg a.s./L. Propineb showed 17.8% respiration inhibition of activated sludge at the highest test concentration of 1000 mg a.s./L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

EC10 or NOEC for microorganisms:

404.4 mg/L