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Ecotoxicological information

Toxicity to microorganisms

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Reference
Endpoint:
activated sludge nitrification inhibition testing
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Remarks:
Basic data given (comparable to guidelines/standards)
Qualifier:
equivalent or similar to guideline
Guideline:
ISO 9509 (Toxicity test for assessing the inhibition of nitrification of activated sludge microorganisms)
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
not specified
Test organisms (species):
Nitrosomonas sp.
Test type:
not specified
Water media type:
freshwater
Limit test:
no
Remarks on exposure duration:
no data
Details on test conditions:
Type: other: Inhibition of N-oxidation
Duration:
24 h
Dose descriptor:
IC50
Effect conc.:
47 mg/L
Nominal / measured:
not specified
Conc. based on:
not specified
Basis for effect:
other: Ammonia use
Conclusions:
The inhibition of nitrification of Nitrosomonas bacteria exposed to 1,2 -dichlorobenzene was investigated using a method similar to ISO DIS 9509. The IC50 (24 h) amounted to 47 mg/L.
Executive summary:

Blum & Speece (1991).

The inhibition of nitrification of Nitrosomonas bacteria exposed to 1,2 -dichlorobenzene was investigated using a method similar to ISO DIS 9509. The IC50 (24 h) amounted to 47 mg/L.

Description of key information

The inhibition of nitrification of Nitrosomonas bacteria exposed to 1,2-dichlorobenzene was investigated by Blum and Speece (1991) using a method similar to ISO DIS 9509. The IC50 (24 h) was reported as 47 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:
47 mg/L

Additional information

The inhibition of nitrification of Nitrosomonas bacteria exposed to 1,2-dichlorobenzene was investigated by Blum and Speece (1991) using a method similar to ISO DIS 9509. The IC50 (24 h) was reported as 47 mg/L.

A number of additional studies (Boyles (1980), McFeters et al (1983), Ribo and Kaiser (1983))) reported lower concentrations but these are not considered as reliable as they were conducted using unsuitable test systems for the assessment of microorganisms in sewage treatment plants e.g. test organisms were marine species. Furthermore, tests with Pseudomonas putida (Bringnamm and Kuehn (1976, 1977, 1980)) are recommended to be used only in cases where no other test results are available.

Therefore the 24 h IC50 of 47 mg/L, reported by Blum and Speece (1991), has been selected as the key value for toxicity of microorganisms to 1,2 dichlorobenzene.