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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1993-02-04 - 1993-10-11
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Also complies with OECD GLP regulations. Deviations were limited, listed below, and are believed not to impact the reliability of the test result.
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
Deviations:
no
GLP compliance:
yes
Remarks:
1 - It is unknown if the analysis to support the characterization of the test material was performed in a GLP compliant manner. 2 - It cannot be confirmed that the percent carbon analysis was performed in a GLP compliant manner.
Specific details on test material used for the study:
- Name of test material (as cited in study report): MRD-92-436; CT-519-92-C
- IUPAC nomenclature - Sodium diisobutyldithiophosphinate
- Appearance - Liquid
- CAS No. 13360-78-6
- Molecular Formula - C8H18PS2.Na
- Molecular Weight - 232 g/mole
- Purity 50% aqueous solution
- Storage condition of test material: At room temperature in the dark
Analytical monitoring:
yes
Details on sampling:
Samples were removed from each treatment on Day 0 and 2 and analyzed for carbon content.
Vehicle:
no
Details on test solutions:
A stock solution was prepared by adding the appropriate amount of neat test material to dillution water in a glass aspirator bottle. The stock solution was mixed (<10% vortex) on a magnetic stirplate with a Teflon coated stirbar for ~1 hour. The nominal treatment levels were 400mg/L, 200mg/L, 100mg/L, 5 mg/L, 25mg/L and a laboratory dilution water control (BW2). Treatment solutions were prepared by adding the appropriate amount of stock solution to laboratory dilution water. Samples were removed from each treatment and analyzed for carbon content.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: Daphnia magna
- Age at study initiation (mean and range, SD): < 24h
- Source: laboratory in-house culture
- Age of parental stock (mean and range, SD): 13d old
- Feeding during test : no
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 h
Remarks on exposure duration:
<1 daphnid / 2mL solution
Post exposure observation period:
Observations for immobilization, abnormal behaviour and appearance of the daphnids were performed on all replicate chambers at 24 and 48 hours.
Hardness:
80 - 82 mg/L (Hardness as CaCO3 reported for water/carrier)
Test temperature:
20.3 degrees C on Test Day 0
19.0 degrees C on Test Day 2
pH:
7.4-7.6
Dissolved oxygen:
8.5 - 9.1 mg/L
Salinity:
no data
Nominal and measured concentrations:
Nominal concentrations: 0 - 25 - 50 - 100 - 200 - 400 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel: 30mL glass beaker
- Material, size, headspace, fill volume: fill volume 25 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- Biomass loading rate: < 1 daphnid / 2 mL of solution

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: ground water from a well located at the testing facility
- Total organic carbon: 1.142 ppm
- Metals: None dected or Below the minimum detection limits
- Pesticides: None detected
- Chlorine: < 0.1 mg/L
- Alkalinity: 29-30 mg/L

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: in the dark

RANGE-FINDING STUDY
- Test concentrations: 0, 3, 10, 70, 300 and 1000 mg/L; 2 replicates of 5 organisms for each treatment level
- Results used to determine the conditions for the definitive study: Total immobilization in the 1000 and 300 mg/L treatment levels and 20% immobilization observed in the 10 mg/L treatment level during the 48-hour exposure period. 10% immobilization was also observed in the remaining treatment levels, including the dilution water control.
Reference substance (positive control):
no
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
340 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
149 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
mobility
Remarks on result:
other: Confidence internals (95%): 121-181 mg/L
Details on results:
The maximum concentration causing no immobilization was 50mg/L. There was no concentration that caused 100% immobilization.
Reported statistics and error estimates:
The 24 hour Effect Concentration (EC50) value was determined using the Graphical Method. The 48 hour EC50 value with 95% confidence intervals was determined using the Probit procedure of SAS and was based on the natural log of the nominal concentrations.

 Treatment (mg/L)     % Immobilization
   24 hours  48 hours
 Control  0
 25
 50  0
 100  0 20 
 200  0 80 
 400  65 95 
Executive summary:

An acute immobilization test was performed to evaluate the toxicity of the test material to Daphnia magna according to OECD TG 202 and under GLP conditions.

The calculated material values ranged from 90 to > 100% of the nominal concentrations and are within the variability of the analytical method. As such, the nominal concentrations were used for statistical evaluation and reporting.

The 48 hour EC50 was calculated to be 149 mg/L with 95% confidence intervals of 121 to 181 mg/L and was based on the natural log of the nominal concentration.

Description of key information

An acute immobilization test was performed to evaluate the toxicity of the test material to Daphnia magna resulting in a 48 hour EC50 of 149 mg/L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
149 mg/L

Additional information

An acute immobilization test was performed to evaluate the toxicity of the test material to Daphnia magna according to OECD TG 202 and under GLP conditions.

The calculated material values ranged from 90 to > 100% of the nominal concentrations and are within the variability of the analytical method. As such, the nominal concentrations were used for statistical evaluation and reporting.

The 48 hour EC50 was calculated to be 149 mg/L with 95% confidence intervals of 121 to 181 mg/L and was based on the natural log of the nominal concentration.