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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Remarks:
experimental data of read across substances
Justification for type of information:
Data for the target chemical is summarized based on the structurally similar read across chemicals
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
other: as mentioned below
Principles of method if other than guideline:
WoE report is based on four toxicity to microorganism studies as-
WoE 2, WoE 3, WoE 4 and WoE 5.
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
yes
Remarks:
WoE 2, WoE 3 and WoE 4, WoE 5: No data available
Details on test solutions:
WoE 2, WoE 3 and WoE 4:
- Sampling method: All stock solutions were prepared in methanol and serially diluted in distilled water to obtain the target concentrations.

WoE 5: No data available
Test organisms (species):
other: WoE 2: Vibrio fisheri, WoE 3: Photobacterium leiognathi SB strain, WoE 4: Tetrahymena sp. and WoE 5: Photobacterium phosphoreum
Test type:
static
Water media type:
saltwater
Total exposure duration:
30 min
Post exposure observation period:
WoE 2: Luminescence inhibition was measured after 15 and 30 min of exposure duration.
WoE 3: Luminescence inhibition of the naturally luminescent marine bacteria Photobacterium leiognathi SB strain was measured after 30 min of exposure duration.
WoE 4: Measurement of growth inhibition of test organism was carried out at 440 nm at 24 and 28 hrs.
Test temperature:
WoE 2, WoE 3, WoE 4: No data available
WoE 5: 15°C
pH:
WoE 2, WoE 3, WoE 4: No data available
WoE 5: pH range used is 5 to 9
Details on test conditions:
WoE 2 and WoE 3:
EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Bacterial luminescence inhibition was measured after 15 and 30 mins of exposure duration to tested solutions.

WoE 4:
EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Measurement of growth inhibition of test organism was carried out at 440 nm at 24 and 28 hrs.

WoE 5: No data available
Reference substance (positive control):
yes
Remarks:
WoE 2 and WoE 3: 2, 4-dichlorophenol (DCP), WoE 4: Potassium dichromate (K2Cr2O7), WoE 5: Recommended reference substance: Phenol and Sodium pentachlorophenate
Duration:
15 min
Dose descriptor:
EC50
Effect conc.:
0.11 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Decrease in bacterial light production.
Remarks on result:
other: WoE 2: For test organism Vibrio fisheri
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
0.11 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Decrease in bacterial light production.
Remarks on result:
other: WoE 2: For test organism Vibrio fisheri
Duration:
30 min
Dose descriptor:
LOEC
Effect conc.:
0.02 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Decrease in bacterial light production.
Remarks on result:
other: WoE 2: For test organism Vibrio fisheri
Duration:
15 min
Dose descriptor:
EC50
Effect conc.:
1.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Decrease in bacterial light production.
Remarks on result:
other: WoE 3: For test organism Photobacterium leiognathi SB strain
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
1.6 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Decrease in bacterial light production.
Remarks on result:
other: WoE 3: For test organism Photobacterium leiognathi SB strain
Duration:
30 min
Dose descriptor:
LOEC
Effect conc.:
0.25 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Decrease in bacterial light production.
Remarks on result:
other: WoE 3: For test organism Photobacterium leiognathi SB strain
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
4.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: WoE 4
Duration:
28 h
Dose descriptor:
EC50
Effect conc.:
5.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: WoE 4
Duration:
28 h
Dose descriptor:
LOEC
Effect conc.:
0.48 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: WoE 4
Duration:
5 min
Dose descriptor:
EC50
Effect conc.:
3.273 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Reduction in light output
Remarks on result:
other: WoE 5
Duration:
15 min
Dose descriptor:
EC50
Effect conc.:
3.859 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Reduction in light output
Remarks on result:
other: WoE 5
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
4.52 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: Reduction in light output
Remarks on result:
other: WoE 5
Results with reference substance (positive control):
No data available

WoE 2:

Table: Toxicity of the test compound in Microtox bioassay test.

 

 

Chemical

Microtox bioassay test

EC50

(15 min)

EC50

(30 min)

LOEC

Test chemical

 

0.11 ± 0.05

 

0.11 ± 04

 

0.02 ± 0.01

WoE 3:

Table:Toxicity of the test compound in ToxScreen bioassay test.

 

 

Chemical

ToxScreen bioassay test

EC50

(15 min)

EC50

(30 min)

LOEC

Test chemical

 

1.3 ± 0.1

 

1.6 ± 0.3

 

0.25

WoE 4:

Table:Toxicity of the test compound in Protoxkit bioassay test.

 

 

Chemical

Protoxkit bioassay test

EC50

(24 hr)

EC50

(28 hr)

LOEC

Test chemical

 

4.3 ± 0.4

 

5.7 ± 0.9

 

0.48

WoE 5:

Table: Toxicity data

 

#

5 m- pT

15 m- pT

30 m- pT

Name

Formula

ppm

M. wt.

1319

1.66

1.59

1.52

Test chemical

C9H10O2

4.54

150.18

 

Where,

Footnote = Purity of chemical (in %) and/or deviation from standard conditions.

pT =Measured concentrations (in log(L/mmol) at which there is a 50% reduction of the light emission relative to controls at the stated exposure times of 5, 15 and 30 min.

ppm =The compound's toxicity expressed in parts per million (ppm) or mg/L. If more than one entry is provided on the same line under the pT headings, preference is given to the 30-min exposure EC50 level, second preference to the 15-min level and third preference to the 5-min level.

Validity criteria fulfilled:
not specified
Conclusions:
On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the EC50 value can be expected to be in the range 0.11 to 5.7 mg/l and LOEC value was expected to be in the range 0.02 to 0.48 mg/l, respectively during the different exposure study duration.
Executive summary:

Data available of the structurally and functionally similar read across chemicals has been reviewed to determine the effect of the test chemical on toxicity to microorganisms. The studies are as mentioned below:

 

Toxicity to micro-organisms study was conducted on three different test organism, i.e, Vibrio fischeri, Photobacterium leiognathi SB strain and Tetrahymena thermophila. Studies were performed on these organisms using different bioassay test i.e, Microtox bioassay, Toxscreen bioassay and Protoxkit bioassay test. All stock solutions were prepared in methanol and serially diluted in distilled water to obtain the target concentrations. The methanol concentration in the exposure solutions, including controls, was 0.01% (v/v) in distillate water in the tested solutions. 2, 4 -dichloro phenol (DCP) was used as control solution for both Microtox bioassay and Toxscreen bioassay, whereas in Protoxkit bioassay test, Potassium dichromate (K2Cr2O7) was used as control substance. Test bacteria were exposed to the test chemical with a total exposure duration of 30 mins & 28 hrs in different bioassay. Bacterial luminescence inhibition was measured after 15 and 30 mins and inhibition in bacterial growth was measured after 24 and 28 hrs. On the basis of these effects on different test organism, the EC50 value can be determined to be in the range 0.11 to 5.7 mg/l and LOEC value was determined to be in the range 0.02 to 0.48 mg/l, respectively during the different exposure study duration.

 

In a supporting weight of evidence study, toxicity study of micro-organism study was carried out for assessing the effect of the test chemical. Study was performed using Photobacterium phosphoreum, strain NRRL-B-11177 (also referred to as Vibrio fischerii, strain NRRL-B-11177) as a test organism at a temperature of 15°C and pH range 5 to 9. Recommneded reference substance that can be used for the study were Phenol and Sodium pentachlorophenate, respectively. When the test bacterium was exposed to the test chemical, reduction in light output was observed. Thus, based on this effect, the EC50 value during 5, 15 and 30 min exposure period was determined to be 3.273, 3.859 and 4.52 mg/l, respectively.

 

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the EC50 value can be expected to be in the range 0.11 to 5.7 mg/l and LOEC value was expected to be in the range 0.02 to 0.48 mg/l, respectively during the different exposure study duration.

Description of key information

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the EC50 value can be expected to be in the range 0.11 to 5.7 mg/l and LOEC value was expected to be in the range 0.02 to 0.48 mg/l, respectively during the different exposure study duration.

Key value for chemical safety assessment

EC50 for microorganisms:
5.7 mg/L

Additional information

Data available of the read across chemicals has been reviewed to determine the effect of the test chemical on toxicity to microorganisms. The studies are as mentioned below:

 

Toxicity to micro-organisms study was conducted on three different test organism, i.e, Vibrio fischeri, Photobacterium leiognathi SB strain and Tetrahymena thermophila. Studies were performed on these organisms using different bioassay test i.e, Microtox bioassay, Toxscreen bioassay and Protoxkit bioassay test. All stock solutions were prepared in methanol and serially diluted in distilled water to obtain the target concentrations. The methanol concentration in the exposure solutions, including controls, was 0.01% (v/v) in distillate water in the tested solutions. 2, 4 -dichloro phenol (DCP) was used as control solution for both Microtox bioassay and Toxscreen bioassay, whereas in Protoxkit bioassay test, Potassium dichromate (K2Cr2O7) was used as control substance. Test bacteria were exposed to the test chemical with a total exposure duration of 30 mins & 28 hrs in different bioassay. Bacterial luminescence inhibition was measured after 15 and 30 mins and inhibition in bacterial growth was measured after 24 and 28 hrs. On the basis of these effects on different test organism, the EC50 value can be determined to be in the range 0.11 to 5.7 mg/l and LOEC value was determined to be in the range 0.02 to 0.48 mg/l, respectively during the different exposure study duration.

 

In a supporting weight of evidence study, toxicity study of micro-organism study was carried out for assessing the effect of the test chemical. Study was performed using Photobacterium phosphoreum, strain NRRL-B-11177 (also referred to as Vibrio fischerii, strain NRRL-B-11177) as a test organism at a temperature of 15°C and pH range 5 to 9. Recommneded reference substance that can be used for the study were Phenol and Sodium pentachlorophenate, respectively. When the test bacterium was exposed to the test chemical, reduction in light output was observed. Thus, based on this effect, the EC50 value during 5, 15 and 30 min exposure period was determined to be 3.273, 3.859 and 4.52 mg/l, respectively.

 

On the basis of the experimental studies of the structurally and functionally similar read across chemical and applying the weight of evidence approach and by evaluating the effect of test chemical on test organism, the EC50 value can be expected to be in the range 0.11 to 5.7 mg/l and LOEC value was expected to be in the range 0.02 to 0.48 mg/l, respectively during the different exposure study duration.

 

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