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Ecotoxicological information

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
06 December 1988 to 21 July 1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted with internationally accepted guidelines but not conducted to GLP.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1989
Report Date:
1990

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OPP 72-2 (Aquatic Invertebrate Acute Toxicity Test)
GLP compliance:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Specific details on test material used for the study:
- Storage condition of test material: Ambient temperature

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Aliquots of Daphnia Synthetic Medium were removed from each stock solution at the beginning of the definitive test and from each tank at the end of the study. Concentrations of Cuprous Thiocyanate were determined under IRI protocol 337633.

Test solutions

Vehicle:
yes
Details on test solutions:
A 100 ppm stock suspension was prepared by adding a weighed amount of Cuprous Thiocyanate to Daphnia Synthetic Medium and making up to the appropriate volume. The Cuprous Thiocyanate was partly dissolved to produced a suspension by stirring overnight using a magnetic stirrer (Initial Limit Test), or by standing in a sonic water bath for 60 min (Second Limit Test and Definitive Test). In the definitive test, the stock suspension was passed through Whatman No. 3 Filter Paper to remove undissolved test material. The resulting solution was used to prepare test tanks.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
- Common name: Daphnia magna (water flea)
- Source: Bred within the laboratory.
- Age at study initiation: Between 6 and 24 h old
- Method of breeding: Bred by acyclical parthenogenesis.
- Feeding during test: Not fed throughout the duration of the study.

Study design

Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h

Test conditions

Hardness:
The total hardness of a sample of the distilled water used to prepare Daphnia Synthetic Medium in this study was measured as 0 mg/L as CaCO3.
Test temperature:
The temperature was measured in one replicate of each test treatment throughout the test. Tanks and test vessels containing Daphnia were held within the laboratory at a temperature of 23-26°C, which is outwith the range of 18-22°C and maximum deviation of ±1°C stated under IRI Protocol. These deviations are not believed to affect the validity of the study. Table 1 in 'Any other information on materials and methods' provides details on the measured temperature at each concentration.
pH:
pH was measured in one replicate of each test treatment throughout the test. Table 1 in 'Any other information on materials and methods' provides details on the measured pH at each concentration.
Dissolved oxygen:
Dissolved oxygen was measured in one replicate of each test treatment throughout the test. Table 1 in 'Any other information on materials and methods' provides details on the measured dissolved oxygen content at each concentration.
Conductivity:
Conductivity was measured in one replicate of each test treatment throughout the test. Table 1 in 'Any other information on materials and methods' provides details on the measured conductivity at each concentration.
Nominal and measured concentrations:
Table 2 provides details on measured and calculated concentrations (see 'Any other information on materials and methods').
Details on test conditions:
TEST SYSTEM
- Test vessel: Glass construction and covered by glass or perspex plate, with ventilation holes to prevent dust contamination.
- Type: Closed
- Fill volume: 100 ml
- Aeration: The water is aerated 2 hours before use.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

OTHER TEST CONDITIONS
- Photoperiod: Vessels were maintained with a photoperiod of 16 h light and 8 h dark, illumination being provided by artificial daylight fluorescent tubes.

Effect parameters measured: Number of immobile Daphnia per concentration, recorded at 24 and 48 h following commencement of definitive study.
Reference substance (positive control):
no

Results and discussion

Effect concentrationsopen allclose all
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
0.038 other: ppm
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% Confidence level
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
0.02 other: ppm
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: 95% Confidence level
Details on results:
The 48 h LC50 value was calculated graphically as 0.02 ppm (see Figure 1) in illustration (graph/picture). The values are based on the mean measured concentration of Cuprous Thiocyanate in the highest tested concentration and calculated in the remaining test solutions.
Reported statistics and error estimates:
Values of the median lethal concentration (LC50) at 24 and 48 h were determined from immobilisation data using probit analysis.

Any other information on results incl. tables

Limit Tests

In an initial test after 24 h exposure, 100% mortalities were observed in a suspension prepared at a nominal concentration of 100ppm Cuprous Thiocyanate. No mortalities were observed at 0 (Control) ppm.

In a further test after 24 h exposure, 30% mortalities were observed in a suspension prepared at a nominal concentration of 10 ppm Cuprous Thiocyanate. No mortalities were observed in tanks prepared by filtering a suspension prepared at a nominal concentration of 10 ppm Cuprous Thiocyanate. 10 % mortalities were observed at 0 (Control) ppm.

Definitive Study

The numbers of dead Daphnia recorded during the study are detailed in Table 3. The LC50 values at 24 and 48 h, with 95% confidence intervals, were calculated by probit analysis:

    95% Confidence Level (ppm)
Time (h) LC50 Value (ppm) Lower Limit Upper Limit
24 0.0379 0.0276 0.0502
48 0.0203 0.0151 0.0254

The 48 h LC50 value was also calculated graphically as 0.02 ppm (see figure 1 in section "Illustrations (graph/picture)".

These values are based on the mean measured concentrations of Cuprous Thiocyanate in the highest tested concentration and calculated concentrations in the remaining test solutions.

Table 3: Determination of Acute Toxicity (LC50) to Daphnia (48h. Static) - Cumulative Number of Mortalities Recorded

  Calculated Concentration of Cuprous Thiocyanate (ppm)*
Time (h) 0 0.014 0.029 0.058 0.115 0.230
24 0 3 9 11 18 20
48 0 6 13 20 20 20

* = Concentrations were calculated from that measured in the highest tested concentration and the dilution factors used to prepare the remaining test solutions.

Applicant's summary and conclusion

Conclusions:
The acute toxicity (EC50) of Cuprous Thiocyanate to Daphnia magna was determined to be 0.0379 ppm at 24 hours and 0.0203 ppm at 48 hours.
Executive summary:

The acute toxicity (EC50) of Cuprous Thiocyanate to Daphnia (Daphnia magna) over a 48 h period, under static conditions, was determined. Test solutions were prepared after removing undissolved Cuprous Thiocyanate, by filtration of a suspension prepared at a nominal concentration of 100 ppm. The intercept and dose response curve and hence EC50 (with 95% confidence limits) were estimated by applying the standard technique of maximum likelihood estimation to the probit model.

Results are as follows:

    95% Confidence Intervals (ppm)
Time (h) EC50 Value (ppm) Lower Limit Upper Limit
24 0.0379 0.0276 0.0502
48 0.0203 0.0151 0.0254

These values are based on the mean measured concentration of Cuprous Thiocyanate in the highest tested concentration and calculated concentrations in the remaining test solutions.