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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
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 test chemical
Justification for type of information:
Experimental data of test chemical is from handbook and collection of data
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: Refer below principle
Principles of method if other than guideline:
WoE was prepared on the basis of toxicity of test chemical on microorganisms including
WoE 1 and WoE 2
GLP compliance:
not specified
Analytical monitoring:
not specified
Vehicle:
yes
Test organisms (species):
other:
Test type:
other: 1. Photobacterium leiognathi SB strain, 2. Tetrahymena thermophila
Total exposure duration:
30 min
Remarks on exposure duration:
24 hrs study was also included and measured
Post exposure observation period:
1. Luminescence inhibition of the naturally luminescent marine bacteria Photobacterium leiognathi SB strain was measured after 30 min of exposure duration.
2. Measurement of growth inhibition of test organism was carried out at 440 nm at 24 and 28 hrs.
Details on test conditions:
1. EFFECT PARAMETERS MEASURED (with observation intervals if applicable): Bacterial luminescence inhibition was measured after 30 mins of exposure duration to tested solutions.
2. 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.
Reference substance (positive control):
not required
Key result
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: 1st study
Key result
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: 2nd study

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

Validity criteria fulfilled:
not specified
Conclusions:
1. Based on decrease in bacterial light production by the test organism Photobacterium leiognathi SB strain, the EC50 value after 15 and 30 exposure duration with the test chemical, EC50 was observed to be 1.3 and 1.6 mg/l, respectively and LOEC value was observed to be 0.25 mg/l.
2. Toxicity to micro-organisms study was conducted on Tetrahymena thermophila for 28 hrs. Protoxkit bioassay test was performed for the toxicity study.
Thus based on both studies chemical toxicity value ranges from 0.48 to 1.6 mg/l.
Executive summary:

Data from various test chemicals was reviewed to determine the toxic nature of the test chemical. The studies are as mentioned below:

In the first study toxicity to micro-organisms study was conducted on Photobacterium leiognathi SB strain for 30 mins. Toxscreen bioassay test was performed for the toxicity study.   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-dichlorophenol (DCP) was used as control solution.   The test bacteria was exposed to the test substance with exposure duration of 15 and 30 mins. Bacterial luminescence inhibition was measured after 15 and 30 mins of exposure to tested solutions.   Based on decrease in bacterial light production by the test organism Photobacterium leiognathi SB strain, the EC50 value after 15 and 30 exposure duration with the test chemical, EC50 was observed to be 1.3 and 1.6 mg/l, respectively and LOEC value was observed to be 0.25 mg/l.

Similar 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. Potassium dichromate (K2Cr2O7) was used as control substance. The test organism was exposed to the test substance with exposure duration 28 hrs. Inhibition in bacterial growth was measured after 24 and 28 hrs of exposure to tested solutions. Based on growth rate inhibition of test organism Tetrahymena thermophila, the EC50 value after 24 and 28 hrs exposure duration was observed to be 4.3 and 5.7 mg/l, respectively and LOEC value ewas determine to be 0.48 mg/l.

Thus based on both studies chemical toxicity value ranges from 0.48 to 1.6 mg/l.

Description of key information

1. Based on decrease in bacterial light production by the test organism Photobacterium leiognathi SB strain, the EC50 value after 15 and 30 exposure duration with the test chemical, EC50 was observed to be 1.3 and 1.6 mg/l, respectively and LOEC value was observed to be 0.25 mg/l.

2. Toxicity to micro-organisms study was conducted on Tetrahymena thermophila for 28 hrs. Protoxkit bioassay test was performed for the toxicity study.

Thus based on both studies chemical toxicity value ranges from 0.48 to 1.6 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:
0.48 mg/L

Additional information

Data from various test chemicals was reviewed to determine the toxic nature of the test chemical. The studies are as mentioned below:

 

In the first study toxicity to micro-organisms study was conducted on Photobacterium leiognathi SB strain for 30 mins. Toxscreen bioassay test was performed for the toxicity study.   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-dichlorophenol (DCP) was used as control solution.   The test bacteria was exposed to the test substance with exposure duration of 15 and 30 mins. Bacterial luminescence inhibition was measured after 15 and 30 mins of exposure to tested solutions.   Based on decrease in bacterial light production by the test organism Photobacterium leiognathi SB strain, the EC50 value after 15 and 30 exposure duration with the test chemical, EC50 was observed to be 1.3 and 1.6 mg/l, respectively and LOEC value was observed to be 0.25 mg/l.

 

Similar 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. Potassium dichromate (K2Cr2O7) was used as control substance. The test organism was exposed to the test substance with exposure duration 28 hrs. Inhibition in bacterial growth was measured after 24 and 28 hrs of exposure to tested solutions. Based on growth rate inhibition of test organism Tetrahymena thermophila, the EC50 value after 24 and 28 hrs exposure duration was observed to be 4.3 and 5.7 mg/l, respectively and LOEC value ewas determine to be 0.48 mg/l.

 

Thus based on both studies chemical toxicity value ranges from 0.48 to 1.6 mg/l.