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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge respiration inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1990-10-29 - 1990-10-31
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Remarks:
The study was conducted under GLP according to ISO 8192:1986 (E) on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation, but the available information allows the conclusion that the test was properly conducted.
Qualifier:
according to
Guideline:
ISO 8192 (Water quality - Test for inhibition of oxygen consumption by activated sludge for carbonaceous and ammonium oxidation)
Version / remarks:
1986 (E)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Weighing-in directly
- Evidence of undissolved material (e.g. precipitate, surface film, etc): yes, above a concentration of 10000 mg/L the test item was not completely soluble in water
Test organisms (species):
activated sludge
Details on inoculum:
- Pretreatment: none
- Initial biomass concentration: 6 g/L TS
- Source: laboratory sewage (OECD)
Test type:
static
Water media type:
freshwater
Limit test:
no
Nominal and measured concentrations:
100, 1000, 10000 mg/L (nominal)
Reference substance (positive control):
yes
Remarks:
3,5-Dichlorphenol
Dose descriptor:
EC50
Effect conc.:
> 10 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
inhibition of total respiration
Remarks:
respiration rate
Remarks on result:
other: no information on duration available
Details on results:
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: substance not completely soluble above a concentration of 10000 mg/L
- Effect concentrations exceeding solubility of substance in test medium: 10000 mg/L
Validity criteria fulfilled:
not specified
Conclusions:
The study was conducted under GLP according to ISO 8192:1986 (E) on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation, but the available information allows the conclusion that the test was properly conducted. Hence, the results can be considered as reliable to assess the effects of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) to aquatic organisms, here, activated sludge.
Taking into account the determined effect value, i.e. EC50 > 10000 mg/L, the substance does not need to be considered as harmful to the environment.
Executive summary:

In a study conducted under GLP according to ISO 8192:1986 (E), 100, 1000, and 10000 mg/L of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) were added to activated sludge and the respiration rate was determined. 3,5-Dichlorphenol served as positive control. The EC50 was determined to be > 10000 mg/L, the substance does not need to be considered as harmful to the environment.

Description of key information

Toxicity to bacteria: EC50 > 10000 mg/L for activated sludge (ISO 8192:1986 (E), static)

Key value for chemical safety assessment

EC50 for microorganisms:
10 000 mg/L

Additional information

The chosen endpoint is the only available study. It was conducted under GLP according to ISO 8192:1986 (E) on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation, but the available information allows the conclusion that the test was properly conducted. Hence, the results can be considered as reliable to assess the effects of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) to aquatic organisms, here, activated sludge.

There is no indication that the study and hence the result are not reliable, and so no additional data is required, no data gaps were identified.

Taking into account the determined effect value, i.e. EC50 > 10000 mg/L, the substance does not need to be considered as harmful to the environment.