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Ecotoxicological information

Toxicity to microorganisms

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Administrative data

Endpoint:
toxicity to microorganisms
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented publication which meets scientific requirements

Data source

Referenceopen allclose all

Reference Type:
publication
Title:
A database of chemical toxicity to environmental bacteria and its use in interspecies comparisons and correlations
Author:
Blum D.J.W. and Speece R.E.
Year:
1991
Bibliographic source:
Research Journal WPCF 63 (3): 198-207
Reference Type:
secondary source
Title:
European Union Risk Assessment Report, Nitrobenzene, CAS No: 98-95-3
Author:
European Chemicals Bureau
Year:
2007
Bibliographic source:
3rd Priority List, Volume: 77

Materials and methods

Principles of method if other than guideline:
Nitrification inhibition test
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent

Test organisms

Test organisms (species):
Nitrosomonas sp.
Details on inoculum:
- Method of cultivation: The seed bacteria were obtained from the mixed liquor of an activated sludge plant treating meat-packing, rendering, and hide curing wastewater. The reactor vessel was a 20-L glass bottle. Diffused aeration. The culture was fed two times per day approximately 1000 mg/L ammonia-nitrogen in an inorganic nutrient solution buffered by sodium bicarbonate.

Study design

Test type:
static
Water media type:
freshwater
Total exposure duration:
24 h

Test conditions

Test temperature:
25 °C
pH:
6.5 - 8.0
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 125 mL sealed serum bottles, test volume 50 mL
- Aeration: normal air plus 25 mL O2
- No. of organisms per vessel: 450 mg/L bacteria suspension
- N2:O2: 1.6:1
- test vessels were shaken

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Measurement of ammonia. Nitrite was checked to ensure tha only toxicity to Nitrosomonas and not Nitrobacter was controlling the rate of metabolic activity.

Results and discussion

Effect concentrations
Duration:
24 h
Dose descriptor:
IC50
Effect conc.:
0.92 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: inhibition of ammonia consumption

Any other information on results incl. tables

The IC50 value was corrected by considering the partitioning of the test substance into the compartment overlaying the test solution in the sealed test vessels by taking into account the Henry's Law constant and the relative volumes of gas and liquid.

Applicant's summary and conclusion