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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:
09 October 2017 to 20 October 2017
Reliability:
1 (reliable without restriction)

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2018

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Lot number: 2000850599
Analysis date: 19 August 2016
Specific details on test material used for the study:
dentification: Tri-o-tolylphosphine
Appearance: Off-white crystalline powder (determined by
Charles River Den Bosch)
Batch: B64002 (Pfizer Lot no. 2000850599)
Purity/Composition: 99%
Test item storage: At room temperature
Stable under storage conditions until: Unknown
CAS number: 6163-58-2

Sampling and analysis

Analytical monitoring:
yes
Details on sampling:
Samples for possible analysis were taken from the SS and the control according to the schedule below. In addition, the filter containing the undissolved residue was kept for possible analysis.
Frequency at t=0 h, t=24 h and t=72 h
Volume 2.0 mL
Storage Samples were stored in a freezer (≤-15°C) until analysis at the analytical laboratory of the Test Facility.
At the end of the exposure period, the replicates with algae were pooled at each concentration before sampling.
Compliance with the Quality criteria regarding maintenance of actual concentrations was checked by running a test vessel at an intermediate item concentration but without algae and samples for analysis were taken at the start, after 24 hours of exposure and at the end of the test period.
Additionally, reserve samples of 2.0 mL were taken from all test solutions for possible analysis. If not already used, these samples were stored in a freezer (≤-15°C) for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.

Test solutions

Vehicle:
no
Details on test solutions:
The batch of Tri-o-tolylphosphine tested was an off-white crystalline powder with a purity of 99.9% and not completely soluble in test medium at the loading rate initially prepared. No correction was made for the purity/composition of the test item.
Preparation of test solutions started with a loading rate of 100 mg/L applying a three-day period of magnetic stirring to ensure maximum dissolution of the test item in medium. Thereafter, the Saturated Solution (SS) was collected by means of filtration through a 0.45 μm membrane filter (RC55, Whatman) and used as the test concentration. All test solutions were clear and colorless at the end of the preparation procedure. Any residual volumes were discarded.

Test organisms

Test organisms (species):
Daphnia magna
Details on test organisms:
At least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions
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 and there was no delay in the production of the first brood
For the test selection of young daphnids with an age of < 24 hours, from parental daphnids of more than two weeks old

Study design

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

Test conditions

Hardness:
180 mg/L expressed as CaCO3
Test temperature:
18-22°C
pH:
7.7 ± 0.3.
Dissolved oxygen:
8.9
Nominal and measured concentrations:
A SS prepared at 100 mg/L (nominal)
Details on test conditions:
The study started with a combined limit/range-finding test. Twenty daphnids per concentration (four replicates, five daphnids per replicate) were exposed to a control and a SS prepared at 100 mg/L. In addition, ten daphnids per concentration (two replicates, five per replicate) were exposed to 1.0 and 10% of the SS in test medium. Test procedureand conditions were similar to those applied in the limit test.
Preparation of test solutions started with a loading rate of 100 mg/L applying a three-day period of magnetic stirring to ensure maximum dissolution of the test item in medium. Thereafter, the Saturated Solution (SS) was collected by means of filtration through a 0.45 µm membrane filter (RC55, Whatman) and used as the test concentration. All test solutions were clear and colorless at the end of the preparation procedure.
Reference substance (positive control):
yes
Remarks:
potassium dichromate

Results and discussion

Effect concentrations
Key result
Duration:
24 h
Dose descriptor:
EC50
Effect conc.:
> 0.005 mg/L
Conc. based on:
test mat.
Basis for effect:
mortality
Remarks on result:
other: Value above the concentration obtained in a SS prepared at 100 mg/L. This concentration was above the solubility limit of the substance in test medium which could not be measured because it was below the limit of detection (i.e. below 0.0055 mg/L)
Details on results:
Analysis of the samples taken during the limit test showed that the measured concentrations were below the limit of detection of the analytical method (i.e. below 0.0055 mg/L) from the start of exposure. Analysis of an aliquot of the filter residue showed that the test item was used for the preparation of the test solutions.

No immobility was observed at both the SS and the control during the test period.
Number of Introduced Daphnids and Incidence of Immobility in the Limit Test

Time (h) Replicate Tri-o-tolylphosphine, %SS at 100 mg/L
Control 100
0 A 5 5
B 5 5
C 5 5
D 5 5
Total introduced 20 20

24 A 0 0
B 0 0
C 0 0
D 0 0
Total immobilised 0 0
Effect % 0 0

48 A 0 0
B 0 0
C 0 0
D 0 0
Total immobilised 0 0
Effect % 0 0

Any other information on results incl. tables

The 24h-EC50and the 48h-EC50for immobilisation of daphnids were above the concentration obtained in a SS prepared at 100 mg/L.This concentration was above thesolubility limit of Tri-o-tolylphosphine in test medium but could not be measured because it was below the limit of detection of the analytical method (i.e. below 0.0055 mg/L).

Applicant's summary and conclusion

Validity criteria fulfilled:
yes
Conclusions:
In conclusion, due to the low solubility of Tri-o-tolylphosphine in test medium, concentration levels that might induce >50% immobility of daphnids could not be reached.
The 24h-EC50 and the 48h-EC50 for immobilisation of daphnids were above the concentration obtained in a SS prepared at 100 mg/L. This concentration was above the solubility limit of Tri-o-tolylphosphine in test medium but could not be measured because it was below the limit of detection of the analytical method (i.e. below 0.0055 mg/L).
Executive summary:

The objective of the study was to evaluate Tri-o-tolylphosphine for its ability to generate acute toxic effects on the mobility of Daphnia magna during an exposure period of 48 hours and, if possible, to determine the EC50 at 24 and 48 hours of exposure. The study procedures described in this report were based on the OECD guideline No. 202, 2004. In addition, procedures were based on the test methods described in the OECD series on testing and assessment number 23, 2000. The batch of Tri-o-tolylphosphine tested was an off-white crystalline powder with a purity of 99.9% and not completely soluble in test medium at the loading rate initially prepared. A limit test was performed based on the results of a preceding combined limit/range-finding test. A Saturated Solution (SS) was prepared at a loading rate of 100 mg/L and used as the test concentration. Twenty daphnids per group (four replicates, five daphnids per replicate) were exposed to a control and to the SS. The total exposure period was 48 hours and samples for analytical confirmation of exposure concentrations were taken at the start and at the end of the test. In addition, the filter containing the undissolved residue was kept for possible analysis. Analysis of the samples taken during the limit test showed that the measured concentrations were below the limit of detection of the analytical method (i.e. below 0.0055 mg/L) from the start of exposure. Analysis of an aliquot of the filter residue showed that the test item was used for the preparation of the test solutions. No immobility was observed at both the SS and the control during the test period. The study met the acceptability criteria prescribed by the study plan and was considered valid. In conclusion, due to the low solubility of Tri-o-tolylphosphine in test medium, concentration levels that might induce >50% immobility of daphnids could not be reached.

The 24h-EC50 and the 48h-EC50 for immobilisation of daphnids were above the concentration obtained in a SS prepared at 100 mg/L. This concentration was above the solubility limit of Tri-o-tolylphosphine in test medium but could not be measured because it was below the limit of detection of the analytical method (i.e. below 0.0055 mg/L).