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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Study period:
15 Jan 1997 - 05 Feb 1997
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
other: EN ISO 10712: 1995
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: stock solution in deionised water (12500 mg/L). pH adjusted to 7.2
- after addition of test substance replicates were shaken at 120 rpm and 23 ± 1 °C in the dark
- sterile preparation of replicates
Test organisms (species):
Pseudomonas putida
Details on inoculum:
- Laboratory culture: strain "Migula, DSM 50026"
- Preparation of inoculum for exposure: concentration of inoculum at test start 50 FNU (Formazin Nephelometric Units), single replicates at test start 5 FNU (1/10 dilution)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
16 h
Test temperature:
23 °C
pH:
7.2
Nominal and measured concentrations:
nominal: 0, 31.5, 100, 312.5, 1000, 3125, and 10000 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 250 mL glass Erlenmeyer flaks; all sterilised before use
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Culture / test medium: the following substances were diluted in water and filled up to 500 mL

solution 1:
NaNO3: 10 g
K2HPO4: 2.4 g
KH2PO4: 1.2 g
yeast extract: 1 g

solution 2:
NaNO3: 10 g
K2HPO4: 2.4 g
KH2PO4: 1.2 g

solution 3:
D(+)-Glucosemonohydrate x H2O: 10 g

solution 4:
MgSO4 x 7 H2O: 4 g
granular iron(III)citrate: 0.01 g

Stock solution: 18 g Agar, 50 mL solution 1, 125 mL solution 3, 100 mL solution 4, 1000 mL water; fluid medium diveded into 6-10 mL portions in culture vials, sealed, and sterilised for 10 min at 121 °C. Afterwards stored at 2 to 4 °C

OTHER TEST CONDITIONS
- Adjustment of pH: yes, 7.2

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : optical density of bacteria suspension was measured at 525 nm with a Merck SQ 118 photometer; measurements at the start and at the end of the test
Reference substance (positive control):
yes
Remarks:
2,3-Dichlorphenol
Key result
Duration:
16 h
Dose descriptor:
EC10
Effect conc.:
> 10 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: turbidity
Key result
Duration:
16 h
Dose descriptor:
EC50
Effect conc.:
> 10 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: turbidity
Results with reference substance (positive control):
EC50 (16 h) > 10 <30 mg/L (demand value: 10 - 30 mg/L)

Table 1: turbidity measurements and median values (FNUs), standard deviations, variation coefficients, and growth inhibition

 

 

Measured FNUs

 

Concentration (mg/L)

Flask 1

Flask 2

Flask 3

Median value

Standard deviation

Variation coefficient

Growth inhibition

Control, 0 h

 

6

 

 

6

 

 

 

Test substance, 16 h

10000

568

570

565

568

2.5

0.4

6.9

 

3125

610

630

585

608

22.5

3.7

0.1

 

1000

600

610

603

604

5.2

0.9

0.8

 

312.5

610

600

608

606

5.2

0.9

0.6

 

100

618

613

630

620

9.0

1.5

-1.8

 

31.5

623

628

605

618

11.8

1.9

-1.5

Reference substance, 16 h

30

5

5

5

5

0

0

100.2

 

10

610

605

618

611

6.292

1.03

-0.3

Control, 16 h

 

603

615

610

609

6.292

1.033

0

Validity criteria fulfilled:
yes

Description of key information

Key value for chemical safety assessment

EC50 for microorganisms:
10 000 mg/L
EC10 or NOEC for microorganisms:
10 000 mg/L

Additional information