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Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From September 21, 2016 to November 30, 2016
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))
GLP compliance:
yes
Test organisms (species):
activated sludge
Details on inoculum:
- Source of inoculum/activated sludge: Dihua sewage treatment plant, Taiwan.
Test temperature:
20 ± 2 °C
pH:
6.83-7.75
Nominal and measured concentrations:
10, 100 and 1000 mg/L
Details on test conditions:
- Aeration: The test mixture was incubated under conditions of forced aeration at 0.5-1.0 L/min with air removed dust and oil.
- No. of vessels per abiotic control (replicates): three
- Sludge concentration: 1.50 g/L
- Nitrification inhibitor used : N-allylthiourea
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorophenol
Key result
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.

Table 1. Oxygen consumption rates for the preliminary test

Group

(mg/L)

Oxygen consumption rate

(mg/Lh)

Average

Coefficient of variation (%)

Blank control group

33.84

34.98

4.61

36.12

Nitrification control group

35.76

Test group

10

31.56

100

41.04

1000

28.68

30.16

11.74

1000

27.60

1000

34.20

Reference control group

1

31.92

10

25.44

100

7.68

Abiotic control group

9.72

9.88

20.70

12.00

 7.92

Table 2. Inhibition rates of total oxygen uptake and EC50 for the preliminary test

Group

(mg/L)

Inhibition rate of total oxygen uptake (%)

Average

EC50(mg/L)

Test group

10

9.78

>1000.00

100

-17.32

1000

18.01

13.78

1000

21.10

1000

2.23

Reference control group

1

8.75

22.17

10

27.27

100

78.04

Validity criteria fulfilled:
yes
Conclusions:
According to OECD 209 test method, the EC50 of Everdirect SH12 for oxygen consumption rate of sludge was greater than 1000 mg/L.
Executive summary:

This test using the procedures outlined in the SuperLab Study Plan for M62-151100088001EN which is based on the SOP for the OECD 209 (SOPE-508) and OECD 209 (OECD, 2010). The results of this OECD 209 test for Everdirect SH12 show that all validity criteria were met. The EC50 of Everdirect SH12 for oxygen consumption rate of sludge was greater than 1000 mg/L.

 

Description of key information

The EC50 of Everdirect SH12 for oxygen consumption rate of sludge was greater than 1000 mg/L (OECD TG 209).

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

For blank control groups at the end of the test, the coefficient of variation of oxygen consumption rate were less than 30% and greater than 20.00 mg/h of per one gram of sludge, respectively. The EC50 of reference control group (3,5-Dichlorophenol) was lied in the range between 2.00 and 25.00 mg/L. All test validity criteria were met. The EC50 of Everdirect SH12 for oxygen consumption rate of sludge was greater than 1000 mg/L.