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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:
guideline study with acceptable restrictions
Reason / purpose:
reference to other study
Qualifier:
according to
Guideline:
other: OECD 301F
GLP compliance:
yes (incl. certificate)
Vehicle:
no
Test organisms (species):
activated sludge, domestic
Details on inoculum:
- Source of inoculum/activated sludge: Municipal sewage plant at Taunusstein-
Bleidenstadt
- Laboratory culture: No
- Method of cultivation: Not applicable
- Storage conditions: Directly used after sampling
- Storage length: Not applicable
- Preparation of inoculum for exposure: Washed twice with minearal nutrient solution, aerated for 4 h,
homogenised for 2 min and filtered
- Pretreatment: None
- Concentration of sludge: 0.35 mg/L dry mass
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
28 d
Post exposure observation period:
no
pH:
6 -8.5.
Nominal and measured concentrations:
124 mg ThOD/L (test substance)
Key result
Duration:
28 d
Dose descriptor:
IC0
Effect conc.:
>= 20.3 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Details on results:
Results are obtained from the inhibition control of a biodegradation study. For 124 mg ThOD/L test substance (+ 170 mg ThOD/L Sodium Benzoate) no inhibition of the respiration rate was observed in actived domestic sludge over the course of 28 days.

In order to determine a possible bacterial toxicity of the test item one test solution with 20.3 mg test item and 50.8 mg sodium benzoate per 500 mL of test solution was tested in parallel.

Conclusions:
Results are obtained from the inhibition control of a biodegradation study. For 124 mg ThOD/L test substance (+ 170 mg ThOD/L Sodium Benzoate) no inhibition of the respiration rate was observed in actived domestic sludge over the course of 28 days.
Executive summary:

Dihexyl ether was tested for biodegradability according to ‘Manometric Respirometry Test' (OECD Guideline 301F). The degradation process was followed by the oxygen uptake in the test solutions using three different test item concentrations (corresponding to 25 mg ThOD/L, 50 mg ThOD/L,and 100 mg ThOD/L) and an additional toxicity control was included.

Neither the test concentrations, nor the toxicity control showed any signed of inhibition during the study period. The toxicity control showed 81% degradation within 28 days, therefore the test item is not considered to be inhibitory according to the OECD 301F test guideline.

Description of key information

Dihexyl ether was tested for biodegradability according to ‘Manometric Respirometry Test' (OECD Guideline 301F). The degradation process was followed by the oxygen uptake in the test solutions using three different test item concentrations (corresponding to 25 mg ThOD/L, 50 mg ThOD/L,and 100 mg ThOD/L) and an additional toxicity control was included. Neither the test concentrations, nor the toxicity control showed any signed of inhibition during the study period.

The toxicity control showed 81% degradation within 28 days, therefore the test item is not considered to be inhibitory according to the OECD 301F test guideline.

Key value for chemical safety assessment

Additional information