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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to
Guideline:
other: Refer below principle
Principles of method if other than guideline:
Inhibitory effects of test chemical Benzimidazole (i.e 1H-benzimidazole) on micro organism species Bacillus spp. was observed using different soil and water samples as inoculum.
GLP compliance:
no
Specific details on test material used for the study:
- IUPAC name: 1H-benzimidazole
- Name of test material (as cited in study report):Benzimidazole
- Molecular formula: C7H6N2
- Molecular weight: 118.1384 g/mol
- Substance type: Organic
- Physical state: Solid
Analytical monitoring:
yes
Details on sampling:
A stock solution (0.276 mg/ml) was prepared in methanol,with an activity of 36 512 dpm/ul).
Vehicle:
yes
Remarks:
methanol
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Methanol
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)):36 512 dpm/ul
Test organisms (species):
Bacillus sp.
Details on inoculum:
Enrichment media and sources of inoculum. Enrichment for benomyl-degrading bacteria was pursued using the following media, made up in tap water:
a. lactate medium:Na-lactate, 0.35 %; MgSOg.7H20, 0.2%; NH4C1, 0.1%; K2HPO4, 0.05%;Benlate, 0.2-1.0 %
b. glutamate-starch medium according to Kielwein (1969):Na-glutamate, 1.0%; starch, 2.0%; KH2PO4, 0.2%; MgSO4.7H20, 0.05 %;Benlate, 0.2-1.0 % .
c. wheat flour medium:
wheat flour, 2.0~ ; Benlate, 0.2-1.0 K

With successive transfers, Benlate concentrations were gradually increased from 0.2-1.0%; since Benlate contains 50% active ingredient (benomyl), the actual benomyl concentration thus increased from 0.1 to 0.5%. In some experiments a lactate medium was used which instead of Benlate contained benomyl or thiabendazole as the selective agent, in concentrations also increasing from 0.1 to 0.5%.

Nine different soil samples (no. 1 : untreated dune sand; nos 2, 3, 4, and 5 : different samples of Benlate-treated greenhouse soil; nos 6 and 7: two samples of Benlate-treated Trio potting soil; nos 8 and 9: two samples of Benlate-treated sand) and tap water (no. 10) and ditch water (no. 11) were employed as sources of inoculum.

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
192 h
Test temperature:
26 deg.C
Reference substance (positive control):
not specified
Key result
Duration:
192 h
Dose descriptor:
EC50
Effect conc.:
> 500 - < 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Reported statistics and error estimates:
Klett-Summerson readings to measure effects.
Validity criteria fulfilled:
not specified
Conclusions:
Bacillus spp. grown in liquid peptone media benzimidazole compounds were inhibitory at concentrations of 500-1000 mg/l.
Executive summary:

Inhibitory effects of test chemical Benzimidazole (i.e 1H-benzimidazole) on micro organism species Bacillus spp. was observed using different soil and water samples as inoculum. Test chemical analytically monitorized by thin-layer chromatography. A stock solution (0.276 mg/ml) was prepared in methanol,with an activity of 36 512 dpm/ul). Methanol were used as a vehicle in which test chemical dissolved. Test conducted under the static system for 192 hrs. During experiment the Effect of benzimidazole derivatives on maximum growth of Bacillus strains was observed to be at concentrations 500-1000 mg/l (reported as ug/ml) using tubes shaken in water bath at 30C; Klett-Summerson readings taken at intervals up to 192 h after inoculation. Based on the EC50 value, chemical consider to be nontoxic.

Description of key information

Toxicity to microorganism:

Inhibitory effects of test chemical Benzimidazole (i.e 1H-benzimidazole) on micro organism species Bacillus spp. was observed using different soil and water samples as inoculum. Test chemical analytically monitorized by thin-layer chromatography. A stock solution (0.276 mg/ml) was prepared in methanol,with an activity of 36 512 dpm/ul). Methanol were used as a vehicle in which test chemical dissolved. Test conducted under the static system for 192 hrs. During experiment the Effect of benzimidazole derivatives on maximum growth of Bacillus strains was observed to be at concentrations 500-1000 mg/l (reported as ug/ml) using tubes shaken in water bath at 30C; Klett-Summerson readings taken at intervals up to 192 h after inoculation. Based on the EC50 value, chemical consider to be nontoxic.

Key value for chemical safety assessment

EC50 for microorganisms:
1 000 mg/L

Additional information

Toxicity to microorganism:

Data for target chemical Benzimidazole (i.e 1H-benzimidazole) for toxicity of microorganism is as mentioned below:

1)Inhibitory effects of test chemical Benzimidazole (i.e 1H-benzimidazole) on micro organism species Bacillus spp. was observed using different soil and water samples as inoculum. Test chemical analytically monitorized by thin-layer chromatography. A stock solution (0.276 mg/ml) was prepared in methanol,with an activity of 36 512 dpm/ul). Methanol were used as a vehicle in which test chemical dissolved. Test conducted under the static system for 192 hrs. During experiment the Effect of benzimidazole derivatives on maximum growth of Bacillus strains was observed to be at concentrations 500-1000 mg/l (reported as ug/ml) using tubes shaken in water bath at 30C; Klett-Summerson readings taken at intervals up to 192 h after inoculation. Based on the EC50 value, chemical consider to be nontoxic.

2)Aim of this study was to determine the effect of test chemical on the population rate of Saccharomyces cerevisiae. Test conducted under the static system for 24 hrs. 25 ml of sterile synthetic media2 were inoculated from a stock culture slant and shaken for 6 to 7 hr at 30 C. After centrifugation and washing, the cells were suspended in fresh sterile media (1.5 X 105cells/ml) and were grown with shaking to a concentration of 1.0 x 107cells/ml (9.5 to 10.5 hrs), at which time aliquots of the culture were transferred into smaller flasks containing the chemical solutions to be tested. After being shaken for 4 hr, aliquots of the culture were removed for mas and count determinations. Culture mass was determined by measurement of turbidity or of dry weights (24 hrs at 105 C). Erlenmeyer flasks were used in the study. After the exposure of test chemical with Saccharomyces cerevisiae for 24 hrs, 50 % cell growth inhibition were observed. The IC50 was determine at 4000 mg/l.

3) Study was conducted to evaluate the effect of test chemical on the Proliferation ratio of Tetrahymena pyriformis (Ciliate). Test conducted under the static system for 60 hrs. Based on the inhibition of proliferation rate of test organism Tetrahymena pyriformis (Ciliate) by the chemical exposure for 60 hrs, the EC50 was determine to be 66.34 mg/l.