Registration Dossier

Administrative data

Endpoint:
activated sludge respiration inhibition testing
Type of information:
other: read-across from constituent CrIII
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

Data source

Reference
Reference Type:
publication
Title:
Effects of organic and inorganic substances on the cell proliferation of L- 929 fibroblasts and Tetrahymena pyriformis GL protozoa used for toxicological bioassays
Author:
Sauvant MP, Pepin D, Groliere CA, Bohatier J
Year:
1995
Bibliographic source:
Bulletin of Environmental Contamination and Toxicology 55: 171–178

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
Exponentially growing cultures of Tetrahymena pyriformis were exposed to the test substance for a total of 9 hours.
Population density was determined every hour by sub-sampling and cell counting via Coulter Counter.
The population growth in each treatment was evaluated in terms of doubling times (DT) relative to the control.
A 50% inhibitory concentration (IC50), for doubling time relative to the control was then determined by regression analysis.
GLP compliance:
not specified

Test material

Reference
Name:
Unnamed
Details on test material:
CrCl3.6H2O or CrCl3

Sampling and analysis

Analytical monitoring:
not specified
Details on sampling:
not reported

Test solutions

Vehicle:
not specified
Details on test solutions:
Stock solutions of the test substance were prepared in deionized water. Further dilutions were made in deionized water. A five-step graded concentration series was used.

Test organisms

Test organisms (species):
Tetrahymena pyriformis
Details on inoculum:
- Laboratory culture: The protozoa (Strain BGL) were grown axenically at 28ºC in the PPYS-defined medium (proteose peptone yeast-extract substrate) containing protose peptone (Difco), yeast extracts (Difco), and inorganic salts. The cells were maintained in exponential growth phase.

- Initial biomass concentration: 10000 cells/ml

Study design

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
9 h
Remarks on exposure duration:
3, 6 and 9 h
Post exposure observation period:
9 h

Test conditions

Hardness:
not reported
Test temperature:
28 °C
pH:
not reported
Dissolved oxygen:
not reported
Salinity:
not reported
Conductivity:
not reported

Results and discussion

Effect concentrationsopen allclose all
Key result
Duration:
3 h
Dose descriptor:
IC50
Effect conc.:
62 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
growth inhibition
Duration:
6 h
Dose descriptor:
IC50
Effect conc.:
54 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
growth inhibition
Duration:
9 h
Dose descriptor:
IC50
Effect conc.:
50 mg/L
Nominal / measured:
nominal
Conc. based on:
element
Basis for effect:
growth inhibition
Results with reference substance (positive control):
no data
Reported statistics and error estimates:
IC50 calculated with the linear regression model.

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The 3h-IC50 of chromium chloride to Tetrahymena pyriformis was 62 mg Cr/L under test conditions. For a test duration of 9 h, an IC50 of 50 mg/L has been obtained; equivalent to 152.3 mg/L CrCl3.