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Ecotoxicological information

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 chemicals
Justification for type of information:
Data is from handbook or collection of data
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
WoE report was prepared based on two toxicity study of microorganism for the test chemical.
GLP compliance:
not specified
Analytical monitoring:
yes
Remarks:
WoE 3
Vehicle:
yes
Remarks:
WoE 3
Test organisms (species):
other: WoE 2: Vibrio fisheri and Perenniporia tephropora was used in WoE 3 study
Details on inoculum:
WoE 2: - Common name: Aliivibrio fischeri
WoE 3: Perenniporia tephropora is a wood decay fungi
Test type:
static
Water media type:
freshwater
Total exposure duration:
15 min
Remarks on exposure duration:
21 days exposure were provided in WoE 3 study
Post exposure observation period:
WoE 2: Light emission of the bacteria was measured after 0, 5 and 15 min of exposure using a Microtoxs Model 500 Toxicity Analyzer.
Test temperature:
WoE 3: 25°C
Nominal and measured concentrations:
WoE 2: Nine concentrations were tested in a 1 : 2 dilution series
Details on test conditions:
WoE 2:
- No. of vessels per concentration (replicates): triplicates

WoE 3:
- No. of vessels per concentration (replicates): quadruplicate
Reference substance (positive control):
not specified
Key result
Duration:
15 min
Dose descriptor:
EC50
Effect conc.:
284 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: WoE 2
Duration:
21 d
Dose descriptor:
other: MIC
Effect conc.:
4.2 other: μmol/cm2
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks:
radial growth
Remarks on result:
other: WoE 3
Reported statistics and error estimates:
WoE 2: The differences tested by ANOVA are highly significant (P < 0.001)
Validity criteria fulfilled:
not specified
Conclusions:
As in the second weight of evidence study after the exposure of Vibrio fischeri with a test chemical for 15 min, bioluminescence inhibition of microorganism was observed and the EC50 was determined to be at 284 mg/l with 95% confidence limit of 241–336 mg/l, whereas in the third study minimum inhibition concentration (MIC) was determined to be > 4.2 umol/cm2. Thus based on the above all studies, it is observed that the test chemical was non toxic.
Executive summary:

Data available for the test chemicals has been reviewed to determine the toxicityof the test chemical on microorganisms. The studies are as mentioned below:

Toxicity to V. fischeri was measured as inhibition of bioluminescence using Microtoxs M500 Rapid Toxicity Testing System equipment and consumables.The assay was carried out as described in the Microtox user’s manual. Nine concentrations were tested in a 1 : 2 dilution series. Test conducted in triplicates. Light emission of the bacteria was measured after 0, 5 and 15 min of exposure using a Microtoxs Model 500 Toxicity Analyzer. The differences tested by ANOVA are highly significant (P < 0.001). After the exposure of Vibrio fischeri with a test chemical for 15 min, bioluminescence inhibition of microorganism was observed and the EC50 was determined to be at 284 mg/l with 95% confidence limit of 241–336 mg/l.

Above study further supported by the study from peer reviewed journal. Principle of this study was to determine the effect of test chemical on the Perenniporia tephropora. Test chemical analytically monitorized by NMRspectroscopy, ES-MS and X-ray crystallography. The toxicity test, cellulose papers i.e. Whatman No. 41, diameter 5.5 cm, thickness 510μm were treated with solutions of the compounds in acetonitrile or water (0.8–8.4μmol cm−2) and allowed to air-dry. Solvent controls were also prepared in the same manner but without addition of the test compound. The cellulose papers were sterilized by gamma irradiation (25 kGy). Under the sterile conditions, the cellulose papers loaded with test chemical were placed in center on 90 mm malt agar plates and inoculated with a small plug (7mm × 5 mm) of the test fungi Perenniporia tephropora. The fungi were sub-cultured on malt agar plates from existing stocks and used within about 7–9 days. After inoculation process, the plates were incubated at 25°C and at 29% relative humidity for three weeks. Fungal growth was scored periodically by measuring its growth diameters. Test was performed in quadruplicate. After the exposure of test chemical with the fungi, chemical did not inhibit fungi (Perenniporia tephropora) growth under bioassay conditions and minimum inhibition concentration (MIC) was determined to be  > 4.2 umol/cm2.

Thus based on the above all studies, it is observed that the test chemical was non toxic.

Description of key information

As in the second weight of evidence study after the exposure of Vibrio fischeri with a test chemical for 15 min, bioluminescence inhibition of microorganism was observed and the EC50 was determined to be at 284 mg/l with 95% confidence limit of 241–336 mg/l, whereas in the third study minimum inhibition concentration (MIC) was determined to be  > 4.2 umol/cm2. Thus based on the above all studies, it is observed that the test chemical was non toxic.

Key value for chemical safety assessment

EC50 for microorganisms:
284 mg/L

Additional information

Data available for the test chemicals has been reviewed to determine the toxicityof the test chemical on microorganisms. The studies are as mentioned below:

Toxicity to V. fischeri was measured as inhibition of bioluminescence using Microtoxs M500 Rapid Toxicity Testing System equipment and consumables.The assay was carried out as described in the Microtox user’s manual. Nine concentrations were tested in a 1 : 2 dilution series. Test conducted in triplicates. Light emission of the bacteria was measured after 0, 5 and 15 min of exposure using a Microtoxs Model 500 Toxicity Analyzer. The differences tested by ANOVA are highly significant (P < 0.001). After the exposure of Vibrio fischeri with a test chemical for 15 min, bioluminescence inhibition of microorganism was observed and the EC50 was determined to be at 284 mg/l with 95% confidence limit of 241–336 mg/l.

Above study further supported by the study from peer reviewed journal. Principle of this study was to determine the effect of test chemical on the Perenniporia tephropora. Test chemical analytically monitorized by NMRspectroscopy, ES-MS and X-ray crystallography. The toxicity test, cellulose papers i.e. Whatman No. 41, diameter 5.5 cm, thickness 510μm were treated with solutions of the compounds in acetonitrile or water (0.8–8.4μmol cm−2) and allowed to air-dry. Solvent controls were also prepared in the same manner but without addition of the test compound. The cellulose papers were sterilized by gamma irradiation (25 kGy). Under the sterile conditions, the cellulose papers loaded with test chemical were placed in center on 90 mm malt agar plates and inoculated with a small plug (7mm × 5 mm) of the test fungi Perenniporia tephropora. The fungi were sub-cultured on malt agar plates from existing stocks and used within about 7–9 days. After inoculation process, the plates were incubated at 25°C and at 29% relative humidity for three weeks. Fungal growth was scored periodically by measuring its growth diameters. Test was performed in quadruplicate. After the exposure of test chemical with the fungi, chemical did not inhibit fungi (Perenniporia tephropora) growth under bioassay conditions and minimum inhibition concentration (MIC) was determined to be  > 4.2 umol/cm2.

Thus based on the above all studies, it is observed that the test chemical was non toxic.