Benzyltriphenylphosphonium chloride

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From August 2017 to March 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

Six daphnids, instead of five, were added to one of the control vessels during the range-finding test. This deviation was considered to have no impact on the overall integrity of the study or the interpretation of the study results and conclusions.

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

- Analytical purity: >=99.5%
- Purity test date: 02 March 2017
- Lot/batch No.: 180739
- Expiration date of the lot/batch: Not specified
- Appearance: Off-white powder
- Storage: At room temperature

Analytical monitoring:

yes

Details on sampling:

SAMPLING FOR ANALYSIS OF TEST CONCENTRATIONS
- Concentrations: Samples for possible analysis were taken from all test concentrations and the control
- Frequency At t=0 h and t=48 h
- Volume 2.0 mL
- Storage Samples were stored in a freezer (≤-15°C) until analysis

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The batch of test item was an off-white powder with a purity of 100% that appeared not completely soluble in test medium at the loading rate initially prepared. Preparation of test solutions started with a loading rate of 100 mg/L applying a 3 day period of magnetic stirring to ensure maximum dissolution of the test item in test medium. Thereafter, the aqueous Saturated Solution (SS) was filtered through a 0.45 µm membrane filter (RC55, Whatman) and used as the highest test concentration. Lower test concentrations were prepared by subsequent dilutions of the SS in test medium. All test solutions were clear and colorless at the end of the preparation procedure. No correction was made for the purity/composition of the test item.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Species: Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions
- Source: In-house laboratory culture with a known history
- Validity of batch: Daphnids originated from a healthy stock, 2nd to 5th brood, showing no signs of stress such as mortality >20%, presence of males, ephippia or discoloured animals
- Characteristics: For the test selection of young daphnids with an age of < 24 hours, from parental daphnids of more than two weeks old
- Feeding during test: No feeding

BREEDING
- Start of each batch: With newborn daphnids, i.e. less than 3 days old, by placing about 250 of them into 5 litres of medium in an all-glass culture vessel
- Max. age of the cultures: 4 weeks
- Renewal of the cultures: After 7 days of cultivation half of the medium twice a week
- Temperature of medium: 18-22°C
- Feeding: Daily, a suspension of fresh water algae
- Medium: M7, as prescribed by Dr. Elendt-Schneider (Elendt, B.-P., 1990: Selenium deficiency in Crustacea. An ultrastructural approach to antennal damage in Daphnia magna Straus. Protoplasma 154, 25-33).

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

180 mg CaCO3/L

Test temperature:

Continuously measured in a temperature control vessel: 20°C

pH:

Measured at the beginning and end of the test:
- control: 8.2 (t=0h) / 8.1 (t=48h)
- test concentrations: 8.1 (t=0h) / 8.1 (t=48h)

Dissolved oxygen:

Measured at the beginning and end of the test:
- control: 9.0 mg/L (t=0h) / 8.1 mg/L (t=48h)
- test concentrations: 9.1-9.2 mg/L (t=0h) / 8.0-8.2 mg/L (t=48h)

Nominal and measured concentrations:

Nominal concentrations (range-finding test): 0.10 - 1.00 - 10.00% of the SS
Nominal concentrations (1st full test): 0.10 - 0.18 - 0.32 - 0.56 - 1.00% of the SS
Nominal concentrations (2nd full test): 0.22 - 0.46 - 1.00 - 2.20 - 4.60% of the SS
Controls: Test medium without test item or other additives

Details on test conditions:

TEST SYSTEM (1st full test)
- Test vessel: 100 mL, all-glass
- Fill volume: 80 mL
- Aeration: No aeration of the test solutions
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST SYSTEM (2nd full test)
- Test vessel: 60 mL, all-glass
- Fill volume: 50 mL
- Aeration: No aeration of the test solutions
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Tap water prepared by Reverse Osmosis

OTHER TEST CONDITIONS
- Adjustment of pH: No adjustment
- Photoperiod: 16 hours photoperiod daily

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobility (including mortality) at 24 hours and 48 hours

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 0.98-1.0 mg/L (95% confidence interval)

Results with reference substance (positive control):

- Results with reference substance valid? Yes
- 48h-EC50 = 0.41 mg/L (range for expected responses: 0.3-1.0 mg/L)

Reported statistics and error estimates:

The 24 and 48h-EC50-values were calculated from the logits of the percentages of affected daphnids and the logarithms of the corresponding test item concentrations using the maximum likelihood estimation method. ToxRat Professional v 3.2.1 (ToxRat Solutions® GmbH, Germany) was used to perform the analyses.

Range-Finding Test

No immobility was observed in the control and at the lowest test concentration throughout the test period, while complete immobility was observed at the two highest test concentrations at the end of the test. Therefore, the expected EC50 was between 0.10 and 1.0% of the SS prepared at a loading rate of 100 mg/L. Samples taken from solutions containing 0.10 and 1.0% of the SS were analysed. The measured concentrations were 0.097 and 0.97 mg/L at the start of the test, respectively. These concentrations remained stable throughout the test, i.e. were 96-97% of initial at the end of the test. It should be noted that, since the measured concentrations at the start of the test were at the level of nominal despite the filtration, any undissolved material filtered was not test item related.

First Full Test

Measured Concentrations

Samples taken from the solution containing 1.0% of the SS were analysed. The actual exposure concentration was 1.0 mg/L at the start of the test, which remained stable throughout the test, i.e. was 100% of initial at the end of the test. It should be noted that, since the measured concentration at the start of the test was at level of nominal despite the filtration, any undissolved material filtered was not test item related.

Experimental Conditions

Test conditions remained within the limits prescribed by the study plan (pH: 6‑9, not varying by more than 1.5 units; oxygen: ≥3 mg/L at the end of the test). The temperature continuously measured in a temperature control vessel varied between 19 and 20°C during the test, and complied with the requirements as laid down in the study plan (18-22°C, constant within 2°C).

Immobility

No immobility was observed in the control and at any of the concentrations tested during the 48 hours of exposure, which was unexpected based on the results of the range-finding test, where complete immobility was observed in the solution containing 1.0% of the SS. Since it was not possible to know what caused such a difference in results, it was decided to perform a second full test with a broader range of concentrations to be tested.

Second Full Test

Measured Concentrations

Samples taken from all test concentrations were analysed. The actual exposure concentrations were 0.19, 0.48, 1.0, 2.3 and 4.7 mg/L in solutions containing 0.22, 0.46, 1.0, 2.2 and 4.6 mg/L, respectively, at the start of the test. These concentrations remained stable throughout the test, i.e. were 95-98% of initial at the end of the test. It should be noted that, since the measured concentration at the start of the test was at level of nominal despite the filtration, any undissolved material filtered was not test item related. Based on these results, the effect parameters were based on analytically confirmed nominal concentrations.

Experimental Conditions

Test conditions remained within the limits prescribed by the study plan (pH: 6‑9, not varying by more than 1.5 units; oxygen: ≥3 mg/L at the end of the test). The temperature continuously measured in a temperature control vessel remained stable at 20°C during the test, and complied with the requirements as laid down in the study plan (18-22°C, constant within 2°C).

Immobility

No immobility was observed in the control and at the two lowest test concentrations, while a dose-related increase of immobility was observed at the three highest test concentrations. The responses recorded in this test allowed for reliable determination of an EC50 and were in line with the results of the range-finding test.

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study with Daphnia magna, the 48h-EC50 for immobilization was 1.0 mg/L based on analytically confirmed nominal concentrations (95% confidence interval between 0.98 and 1.0 mg/L).

Executive summary:

The toxicity of the test item to the freshwater flea Daphnia magna was investigated in a GLP-compliant study performed in accordance with OECD Guideline No. 202. The EC50 for immobilization (48h-EC50) was 1.0 mg/L with a 95% confidence interval ranging from 0.98 to 1.0 mg/L.

Description of key information

The toxicity of the test item to the freshwater flea Daphnia magna was investigated in a GLP-compliant study performed in accordance with OECD Guideline No. 202. The EC50 for immobilization (48h-EC50) was 1.0 mg/L with a 95% confidence interval ranging from 0.98 to 1.0 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 mg/L

Additional information

The toxicity of the test item to freshwater flea Daphnia magna was investigated in one GLP-compliant study performed in accordance with standard methods, with minor deviations. The study is considered as reliable (Klimisch 1) and is selected as a key study for the endpoint.