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Toxicity to microorganisms

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Reference
Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
Data is from peer-reviewed journal
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Determination of the biological effect of chloral hydrate in Entosiphon sulcatum by cell multiplication inhibition test.
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material: 2,2,2-Trichloroethane-1,1-diol (Chloral hydrate)
- Molecular formula: C2-H3-Cl3-O2
- Molecular weight: 165.4026g/mol
- Smiles notation: C(C(O)O)(Cl)(Cl)Cl
- InChl: RNFNDJAIBTYOQL-UHFFFAOYSA-N
- Substance type: Organic
- Physical state: Solid
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Entosiphon sulcatum
Details on inoculum:
To prepare feeding of the Entosiphon stock or preliminary cultures with bacteria, decant nutrient solution and suspend the bacterial centrifugate with a quantity of a 50% solution of stock solution I in sterile double-distilled water until the initial volume is reached again. Centrifuge and decant again this suspension as described above. Take up the centrifugate with a 50°/0 solution of stock solution I in sterile double-distilled water.
Test type:
not specified
Water media type:
freshwater
Total exposure duration:
72 h
Hardness:
No data
Test temperature:
25°C
pH:
6.9
Dissolved oxygen:
No data
Salinity:
No data
Nominal and measured concentrations:
No data
Details on test conditions:
For maintenance of the test strain of Entosiphon sulcatum continuously inoculate the expected required number of stock cultures at 72 h or 96 h intervals. For this, mix 8 ml of stock solution I and 8 ml of sterile double-distilled water in 300-ml Erlenmeyer flasks stoppered with metal caps and add 2 ml of a stock culture and 2 ml of the adjusted bacterial suspension for Entosiphon stock cultures. Store stock cultures at 25°C. Before inoculation control the flasks containing the stock cultures by means of an inverse microscope. Pretreatment of the bacteria used for feeding preliminary cultures of Entosiphon sulcatum does not differ from that of bacteria used for feeding the stock cultures. Keep preliminary cultures at 25°C over 72 h before using them for inoculation of the test cultures. Before inoculation control each flask containing the preliminary cultures by means of an inverse microscope.
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EC0
Effect conc.:
< 79 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
test mat.
Basis for effect:
other: Multiplication of the cells was inhibited at this concentration

Using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of chloral hydrate was determined for flagellate protozoa (Entosiphon sulcatum).

Validity criteria fulfilled:
not specified
Conclusions:
EC0 was found to be < 79mg/l for Chloral hydrate in Entosiphon sulcatum when it was exposed for 72 h based on inhibition of cell multiplication.
Executive summary:

In toxicity to microorganism study for Chloral hydrate the biological effect was evaluated by using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of chloral hydrate was determined to be 79 mg/l for Entosiphon sulcatum. Therefore EC0 was considered to be <79mg/l for 72h for Entosiphon sulcatum.

 

Description of key information

EC0 was found to be <79mg/l for Chloral hydrate in Entosiphon sulcatum when it was exposed for 72 h. Since there was no inhibition in cell multiplication, EC0 was considered to be equivalent to NOEC and the value for the same was considered to be 79 mg/L. Thus the substance 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) can be concluded to be non toxic to microorganisms.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
79 mg/L

Additional information

Two studies on two different microorganisms were reviewed for the substance 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) for the same peer reviewed journal. The same are represented below as key and supporting studies:

In key toxicity to microorganism study for Chloral hydrate the biological effect was evaluated. By using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of chloral hydrate was determined to be 79 mg/l for Entosiphon sulcatum. Therefore EC0 was considered to be <79mg/l for 72h for Entosiphon sulcatum.

 

While in supporting toxicity to microorganisms study for Chloral hydrate the biological effect was evaluated. By using analogous methods of the cell multiplication inhibition test, the toxicity threshold (TT) of chloral hydrate was determined to be 1.6 mg/l for bacteria Pseudomonas putida. Therefore EC0 was considered to be 1.6 mg/l for 16 h for Pseudomonas putida.

Considering the EC0 values i.e. no effects observed on cell multiplication of both the species the substance 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) can be concluded to be non toxic to microorganisms.