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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 from various test chemicals
Justification for type of information:
experimental data from various test chemicals
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 report is prepared based on toxicity to microorganisms study:
1 and 2nd
GLP compliance:
no
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
other: 1. Staphylococcus aureus, 2. activated sludge
Details on inoculum:
1. - Laboratory culture: micro-organisms were collected from the stock of the Department of Pharmaceutical Microbiology,
- Method of cultivation: The test organisms were maintained on nutrient agar slopes and kept in a refrigerator at 4 °C.
Test type:
static
Water media type:
other: 1. Nutrient agar, 2. freshwater
Limit test:
no
Total exposure duration:
24 h
Remarks on exposure duration:
3 hrs exposure was carried out in the 2nd study
Test temperature:
1. 37°C
pH:
2. 7.5
Reference substance (positive control):
yes
Remarks:
1. The positive control for bacteria is gentamicin at the concentration of 5 mg/ml
Key result
Duration:
24 h
Dose descriptor:
other: MIC
Effect conc.:
200 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth inhibition
Remarks on result:
other: 1st study
Duration:
3 h
Dose descriptor:
EC50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks on result:
other: 2nd study
Validity criteria fulfilled:
no
Conclusions:
1. The minimum inhibition concentration (MIC) of test chemical on Staphylococcus aureus was observed to be 200mg/l.
2. Test chemical when evaluated for toxicity to microorganisms on Activated sludge for 3 hrs the EC50 value was observed to be > 1000 mg/l.
Thus based on the above effects chemical toxicity value ranges from 200 to > 1000 mg/l.
Executive summary:

In different studies, the given test chemical, has been investigated for toxicity to microorganisms to a greater or lesser extent. The studies are summarized as below –

 

In the first key study evaluation of toxicity of test chemical on Staphylococcus aureus toxicity to micro-organisms test was carried for 24 h under static condition.An overnight culture of each organism S. aureus was prepared. The 0.1 ml of organism was taken into 9.9 ml of sterile distilled water (SDW) to give 10 ml of 1:100 (10 ) dilution. The stock was maintained on nutrient agar slant and sub-cultured in nutrient broth for incubation at 37 °C prior to each antimicrobial testing. Inoculation of the test organisms on nutrient agar-prepared plates was achieved by flaming a wire loop on a spirit lamp, cooling the wire loop (air cooling) and fetching the test organisms.The discs were prepared using a Grade No. 1 Whatman filter paper. One hundred discs were obtained by punching and putting in vial bottles and sterilizing in an oven at 150 °C for 15 min. Thereafter the cups (9 mm diameter) were aseptically bored into the solid nutrient agar using a sterile cork-borer. The test solution of Methyl salicylate was introduced .The plates were left at room temperature for 2 h, allowed to diffuse into the medium, turned upside-down and thereafter incubated at 37 °C for 24 h in an incubator. The minimum inhibition concentration (MIC) of test chemical on Staphylococcus aureus was observed to be 200mg/l.

First study was supported by the second study from peer reviewed journal. To evaluate antibacterial activity of  test chemical on Activated sludge toxicity to micro-organisms test was carried out according to the OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test. The test was carried for 3 h under static condition. Test chemicalwas used as a test material to evaluate toxicity to microorganisms as per OECD guideline 209. Activated sludge was used as the test culture at pH 7.5 for 3 h The EC50 value on the basis of respiration inhibition test was observed to be >1000 mg/l.

Thus based on the above effects chemical toxicity value ranges from 200 to > 1000 mg/l.

Description of key information

1. The minimum inhibition concentration (MIC) of test chemical on Staphylococcus aureus was observed to be 200mg/l.

2. Test chemical when evaluated for toxicity to microorganisms on  Activated sludge for 3 hrs the EC50 value was observed to be > 1000 mg/l.

Thus based on the above effects chemical toxicity value ranges from 200 to > 1000 mg/l.

Key value for chemical safety assessment

EC50 for microorganisms:
200 mg/L

Additional information

In different studies, the given test chemical and structually and functionally similar read across chemicals has been investigated for toxicity to microorganisms to a greater or lesser extent. The studies are summarized as below –

 

In the first key studyevaluation of toxicity of test chemical on Staphylococcus aureus toxicity to micro-organisms test was carried for 24 h under static condition.An overnight culture of each organism S. aureus was prepared. The 0.1 ml of organism was taken into 9.9 ml of sterile distilled water (SDW) to give 10 ml of 1:100 (10 ) dilution. The stock was maintained on nutrient agar slant and sub-cultured in nutrient broth for incubation at 37 °C prior to each antimicrobial testing. Inoculation of the test organisms on nutrient agar-prepared plates was achieved by flaming a wire loop on a spirit lamp, cooling the wire loop (air cooling) and fetching the test organisms.The discs were prepared using a Grade No. 1 Whatman filter paper. One hundred discs were obtained by punching and putting in vial bottles and sterilizing in an oven at 150 °C for 15 min. Thereafter the cups (9 mm diameter) were aseptically bored into the solid nutrient agar using a sterile cork-borer. The test solution of Methyl salicylate was introduced .The plates were left at room temperature for 2 h, allowed to diffuse into the medium, turned upside-down and thereafter incubated at 37 °C for 24 h in an incubator. The minimum inhibition concentration (MIC) of test chemical on Staphylococcus aureus was observed to be 200mg/l.

First study was supported by the second study from peer reviewed journal. To evaluate antibacterial activity of  test chemical on Activated sludge toxicity to micro-organisms test was carried out according to the OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test. The test was carried for 3 h under static condition. Test chemicalwas used as a test material to evaluate toxicity to microorganisms as per OECD guideline 209. Activated sludge was used as the test culture at pH 7.5 for 3 h The EC50 value on the basis of respiration inhibition test was observed to be >1000 mg/l.

Thus based on the above effects chemical toxicity value ranges from 200 to > 1000 mg/l.