Bis(p-methoxyphenyl)iodonium bromide

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:

15 January - 19 March 2019

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)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

not specified

Vehicle:

no

Details on test solutions:

The test solutions used in the test were prepared by mechanical dispersion without using any solubilising agent. After the formulation procedure the test animals were immediately introduced into the test solution.
A stock solution was first prepared by dissolving an amount of 0.01 g test item in 1000 mL dilution water (ISO medium) using 10 min shaking at ~300 rpm to obtain clear solution resulting a nominal concentration of 10 mg/L.

Test organisms (species):

Daphnia magna

Details on test organisms:

Species and strain: Daphnia magna (Straus)
Origin: Laboratory of Hydrobiology (Central Agricultural Office, Directorate of Plant-, and Soil Protection)
Breeding: The Daphnia are bred in the Laboratory of TOXI-COOP ZRT.
Number of animals: Twenty animals in each group (concentrations and untreated control), divided into 4 concurrent batches (5 animals per batch).
Age of animals: Less than 24 h old at the beginning of the test.
Sex: Female
Animal health: Apparently healthy animals were used in this test with a known history
Acclimatization: Test animals were bred under similar (or the same) conditions as that used during the exposure period (holding water, temperature, background colour etc.), therefore additional acclimatisation before the test was not necessary. Brood daphnids were maintained in dilution water at the test temperature for at least 48 hours prior to the start of the test.
Food and Feeding: The Daphnia were fed with concentrated algal suspension of Raphidocelis subcapitata during the holding. Test animals were not fed during the exposure.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

The reconstituted water (ISO medium) has an approximate theoretical total hardness of 249 mg/L (as CaCO3).

Test temperature:

The test temperature was in the range of 21.1 – 21.7°C measured in the test vessels during the test. The additionally measured ambient temperature within the climate chamber was between 20.5 – 21.8°C.

pH:

The pH of the test solution was not adjusted and not varied by more than 1.5 units in any one test. The pH was in the range of 7.39 – 7.94 during the test.

Dissolved oxygen:

The dissolved oxygen concentration was in the range of 6.98 – 7.68 mg/L during the test.

Nominal and measured concentrations:

The test solutions of chosen test concentrations were prepared by appropriate diluting of this stock solution:
Nominal
concentration [mg/L] Stock Solution [mL] ISOMedium [mL]
10.0 300 -
5.7 171 q.s. ad 300
3.3 98 q.s. ad 300
1.9 56 q.s. ad 300
1.1 32 q.s. ad 300

Details on test conditions:

Twenty animals, divided into four groups (glass beaker; volume app. 50 mL) of five animals each were exposed to the test concentrations and to the control for 48 hours. The test animals were not fed during the test.
Each test vessel contained approximately 40 mL of test solution and was uniquely identified with study number, test group and replicate.
The immobility or mortality of the Daphnia was determined by visual observation after 24 and 48 hours of exposure. Those animals not able to swim within 15 seconds after gentle agitation of the test beaker were considered to be immobile.For determination of the test item concentrations, samples were taken from each test concentration and the control at the start and at the end of the test. Four replicate samples were analysed (5 mL per replicate) in each case. The analysis was performed by the analytical laboratory of TOXI-COOP ZRT according to the results of the analytical method validation (Study number: 880-100-4218) using HPLC method with UV detection.

Reference substance (positive control):

yes

Remarks:

Name: Potassium dichromate (K2Cr2O7) CAS No.: 7778-50-9 Batch No.: K50498364 Expiry Date: 31 July 2023 Supplier: MERCK

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

3.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

4.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

Nominal concentrations of 1.1, 1.9, 3.3, 5.7 and 10.0 mg/L were investigated in the main study. The concentrations of the test item were analytically determined at the start and at the end of the test.
The measured concentrations were in the range of 93 – 99 % of the nominal at the start and 95 – 104 % at the end of the test (i.e. within ± 20 % during the experiment) therefore the biological results are based on the nominal concentrations.

Results with reference substance (positive control):

No immobilisation was observed in the control group (􀂔 10 %) and the dissolved oxygen concentration at the end of the test in control and test vessels was more than 3 mg/L in all cases. All validity criteria were within acceptable limits and therefore the study can be considered as valid.

Validity criteria fulfilled:

yes

Conclusions:

In this 48-hour acute toxicity test on Daphnia magna, the obtained results showed that the test item DIMETHOXYDIPHENYL-IODONIUMBROMID had significant toxic effects on the mobility of Daphnia.
The 48-h EC50 value was determined to be 5.4 mg/L (95 % conf. limits: 4.7 – 6.2).
The 48-h NOEC was determined to be 3.3 mg/L.
All validity criteria were met. The results are based on nominal test item concentrations.

Executive summary:

Test item: DIMETHOXYDIPHENYL-IODONIUMBROMID (Batch No.: B486663)
Test species: Daphnia magna (Straus)
Dilution water: ISO medium, prepared in the laboratory of TOXI-COOP ZRT.
Concentrations: Nominal concentrations of 1.1, 1.9, 3.3, 5.7 and 10.0 mg/L were investigated in the main study. Concurrent control ran.
Measured test item concentrations remained within ± 20 % of the nominal over the test period of 48 hours, therefore the biological results are based on the nominal concentrations.
Test design: Twenty animals, divided into four groups (glass beaker; volume app. 50 mL) of five animals each were exposed to the test concentrations or run as control for 48 hours in a static test.
The immobility or mortality of the Daphnia was determined by visual observation after 24 and 48 hours of exposure.
Analytics: For determination of the test item concentrations, samples were taken from each concentration level and control at the start and at the end of the test. Concentrations were determined using HPLC method with UV detection.
Endpoints: EC10, EC20, EC50, NOEC and LOEC for 48h test period.
Statistics: For determination of the ECx values Probit analysis was used by SPSS software. No statistical procedure was necessary to determine NOEC and LOEC.
Validity: All validity criteria were met and therefore the study can be considered as valid (see section 8.1)
Results: Biological results are based on the nominal concentrations.
The biological endpoints are summarised below in Table 1.

Table 1: Summary of the Biological Endpoints

Endpoint	Concentration [mg/L] based on nominal concentrations
48 h-EC10 95 % conf. limits	4.1 2.6 – 4.7
48 h-EC20 95 % conf. limits	4.5 3.3 – 5.1
48 h-EC50 95 % conf. limits	5.4 4.7 – 6.2
48 h-NOEC	3.3
48 h-LOEC	5.7

 

Description of key information

In the 48-hour acute toxicity test on Daphnia magna, the obtained results showed that the test item DIMETHOXYDIPHENYL-IODONIUMBROMID had significant toxic effects on the mobility of Daphnia.
The 48-h EC50 value was determined to be 5.4 mg/L (95 % conf. limits: 4.7 – 6.2). The 48-h NOEC was determined to be 3.3 mg/L.
All validity criteria were met. The results are based on nominal test item concentrations.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

5.4 mg/L