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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
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
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to guideline
Guideline:
other: refer below principle
Principles of method if other than guideline:
The toxic effect of test chemical in Photobacterium phosphoreum (strain: FEI 162095) was observed for 15 min.
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Photobacterium phosphoreum
Details on inoculum:
- Strain: strain FEI 162095
- Laboratory culture: The freeze-dried Photobacterium phosphoreum bacteria were reconstituted by adding 12.5-ml 2% NaCl into the reagent bottle and incubating it at +4°C for 20 min before use.
Test type:
static
Water media type:
not specified
Total exposure duration:
15 min
Test temperature:
15°C
Reference substance (positive control):
not specified
Key result
Duration:
15 min
Dose descriptor:
EC50
Effect conc.:
28 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: 50 percent reduction in light
Validity criteria fulfilled:
not specified
Conclusions:
The effect concentration i.e EC50 value of test chemical was considered to be 28 mg/l for micro organism species Photobacterium phosphoreum in 15 min.exposure period.
Executive summary:

Toxicity test was performed with Laboratory-prepared freeze-dried photobacterial reagent (Photobacterium phosphoreum strain FEI 162095) registered in the Finnish Environment Institute. The freeze-dried bacteria were reconstituted by adding 12.5-ml 2% NaCl into the reagent bottle and incubating it at +4°C for 20 min before use. The concentration of test chemical in the test (mg/L) which caused a 50% reduction in light after exposure of was measured after an exposure period of 15 min. The EC50 value of test chemical was determined to be 28 mg/l for Photobacterium phosphoreum bacteria.

Description of key information

Toxicity test was performed with Laboratory-prepared freeze-dried photobacterial reagent (Photobacterium phosphoreum strain FEI 162095) registered in the Finnish Environment Institute. The freeze-dried bacteria were reconstituted by adding 12.5-ml 2% NaCl into the reagent bottle and incubating it at +4°C for 20 min before use. The concentration of test chemical in the test (mg/L) which caused a 50% reduction in light after exposure of was measured after an exposure period of 15 min. The EC50 value of test chemical was determined to be 28 mg/l for Photobacterium phosphoreum bacteria.

Key value for chemical safety assessment

EC50 for microorganisms:
28 mg/L

Additional information

Various experimental studies of the test chemical were reviewed for toxicity to micro-organisms end point which are summarized as below:

 

In an experimental study from peer reviewed journal (2000), toxicity test was performed with Laboratory-prepared freeze-dried photobacterial reagent (Photobacterium phosphoreum strain FEI 162095) registered in the Finnish Environment Institute. The freeze-dried bacteria were reconstituted by adding 12.5-ml 2% NaCl into the reagent bottle and incubating it at +4°C for 20 min before use. The concentration of test chemical in the test (mg/L) which caused a 50% reduction in light after exposure of was measured after an exposure period of 15 min. The EC50 value of test chemical was determined to be 28 mg/l for Photobacterium phosphoreum bacteria.

 

In a supporting weight of evidence study, mirotox test was performed with Vibrio fischeri to assess the toxicity of test chemical. MicrotoxTM Reagent (Vibrio fischeri NRRL-B 11177). (AZUR Environmental, Carlsbad, California, USA). The freeze-dried reagent was reconstituted and bacteria cultivated, harvested, and frozen in cryoprotectant as described in paper (Kahru et al., 1996). The thawed bacterial suspension was used for the toxicity tests. The amount of viable bacteria in the case of all photo bacterial tests was ~10⁶ bacteria per ml test solution. The concentration of test chemical in the test (mg/L) which caused a 50% reduction in light was measured after exposure of test chemical for 15 min. The EC50 value of test chemical was considered to be 5.3 mg/l in Vibrio fischeri NRRL-B 11177.

 

Biotox test was performed with Vibrio fisheri to find toxicity of test chemical. Vibrio fisheri 1500 Reagent (Vibrio fischeri NRRL-B11177) from the BioTox test (Labsystems, Helsinki, Finland). The freeze-dried reagent was reconstituted with 12.5-ml 2% NaCl, incubated at +4°C for 20 min and, prior to the assay, further diluted five-fold with 2% NaCl. The concentration of test chemical in the test (mg/L) which caused a 50% reduction in light was measured after exposure of test chemical for 15 min. The EC50 value of test chemical was considered to be 5.2 mg/l in Vibrio fischeri NRRL-B 11177.

 

For the test chemical, toxicity study of micro-organism study to the test chemical was conducted using Photobacterium phosphoreum, strain NRRL-B-11177 (also referred to as Vibrio fischerii, strain NRRL-B-11177) (Klaus L.E. Kaiser et. al., 1991). The study was performed at a temperature of 15°C and pH range 5 to 9, respectively. Recommneded reference substance that can be used for the study were Phenol and Sodium pentachlorophenate, respectively. Test bacteriumPhotobacterium phosphoreum, strain NRRL-B-11177 was exposed to the test chemical, reduction in light output was observed. Thus, based on this effect, the EC50 value during 30 min exposure period was determined to be 3.36 mg/l.

 

On the basis of the experimental studies, the EC50 value of the test chemical on test organism was determined to be ranges from 3.36 to 28 mg/l.