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Ecotoxicological information

Short-term toxicity to fish

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Administrative data

Endpoint:
short-term toxicity to fish
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: 2b: study with acceptable restrictions

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2005

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 203 (Fish, Acute Toxicity Test)
Qualifier:
according to
Guideline:
EU Method C.1 (Acute Toxicity for Fish)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test substance: 32.9% solution in water
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
not relevant

Sampling and analysis

Analytical monitoring:
yes

Test organisms

Test organisms (species):
Danio rerio (previous name: Brachydanio rerio)
Details on test organisms:
Batch n° 03/Br/04/1 was supplied by Aquatrade International BV. Fish were placed under the test conditions 150 days before beginning of the test. Fish selected for the test were all from the same batch and were of the same age with a size ranging from 3.3 to 3.6 cm.

Study design

Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h

Test conditions

Test temperature:
22.5 +/- 1ºC
pH:
From 6.63 to 6.95 whatever the concentration considered
Dissolved oxygen:
From 80 to 236% whatever the concentration considered
Nominal and measured concentrations:
nominal concentrations of 0.95, 1.7, 3.1, 5.6, or 10 mg active ingredient (a.i.)/L
Details on test conditions:
- closed test vessels
- programmed lighting which provided a controlled lighting cycle (12 hours light/12 hours dark)
- renewal of the solutions every 24 hours.
- Two replicate test chambers were maintained for each treatment and control group, with 5 fish per chamber, for a total of 10 fish per test concentration.

Sodium mercaptide being unstable at neutral pH, test was carried out in closed reactors.

Results and discussion

Effect concentrationsopen allclose all
Duration:
96 h
Dose descriptor:
LC0
Effect conc.:
0.53 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
1.8 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Details on results:
At test initiation and termination, the test solutions were observed to be clear and no precipitate was recorded.  The following mean measured concentration values were used to calculate the median lethal doses.

Despite the renewal of test medium every 24 hours, the concentration of sodium methanethiolate decreased by over 20% in the aged solutions.  The exposure concentration was therefore considered to be equivalent to the mean measured concentration of the initial fresh (excluding the 0 hour sample) and the same concentration 'aged' for 24 hours and this exposure concentration was used to calculate the median lethal concentrations.

The examination of the fish did not reveal any abnormal behavior over the course of the study.  At the higher concentrations of test substance, the fish showed red gills and low mobility. 

Based on the mean measured test concentrations and the mortality results, the median lethal concentrations were determined to be as follows: Results LC50-24h = 2.9     LC50-48h = 2.9       LC50-72h = 2.0       LC50-96h = 1.8
Results with reference substance (positive control):
The sensitivity of fish is tested at least once for each new batch of fish. For reference, the results of the last test carried out on November 13, 2003 gave a LC50-24h of 230 mg/L.

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Remarks:
Except the concentrations which were not maintained constant during the exposure phase. Concentration in the air phase was not measured.
Conclusions:
96-Hour LC50: 1.8 mg sodium methanethiolate (a.i.)/L
95% Confidence Limits: Not determined
No-Mortality Concentration: 0.53 mg sodium methanethiolate (a.i.)/L