5,5'-diisopropyl-2,2'-dimethylbiphenyl-4,4'-diyl dihypoiodite

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:

20 April 2018 to 01 May 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)

Version / remarks:

2004

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: OECD Guideline 23 (• Guidance document on aquatic toxicity testing of difficult substances and mixtures)

Version / remarks:

2000

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Samples for possible analysis were taken from all test concentrations and the control according to the schedule below. In addition, the filter containing the undissolved residue was kept for possible analysis.
- Schedule:
Frequency at t=0 h and t=48 h
Volume 2.0 mL from the approximate centre of the test vessels
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 were pooled at each concentration before sampling.
Additionally, reserve samples of 2.0 mL were taken for possible analysis. If not 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.

Vehicle:

no

Details on test solutions:

The test material was not completely soluble in test medium at the loading rates initially tested. No correction was made for the purity/composition of the test material.
Preparation of test solutions started with loading rates individually prepared ranging between 1.0 and 100 mg/L. A 3-day period of magnetic stirring was applied to ensure maximum dissolution of the test material in medium. Thereafter, the aqueous Water Accommodated Fractions (WAFs) were collected by means of filtration through a 0.45 µm membrane filter (RC55, Whatman) and used as test concentrations. All test solutions were clear and colourless at the end of the preparation procedure.
Any residual volumes were discarded.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain/clone: Straus, 1820
- Source: In-house laboratory culture with a known histor. Test daphnia were 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.
- Age of parental stock: 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

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.
- Maximum 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 (Adjusted ISO medium)

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

19 - 21 °C

pH:

7.8 - 8.2

Dissolved oxygen:

8.6 - 9.7 mg/L

Nominal and measured concentrations:

WAFs prepared at loading rates of 1.0, 10 (range finding) and 100 mg/L (limit test).

Details on test conditions:

TEST SYSTEM
- Test vessel: 60 mL, all-glass
- Fill volume: 50 mL
- Aeration: no
- 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: Adjusted ISO medium (M7)
- Adjusted ISO medium (M7) was composed of the following dissolved in tap water purified by Reverse Osmosis: CaCl2.2H2O (211.5 mg/L), MgSO4.7H2O (88.8 mg/L), NaHCO3 (46.7 mg/L), KCl (4.2 mg/L), B (0.125 mg/L), Fe (0.05 mg/L), Mn (0.025 mg/L), Li, Rb and Sr (0.0125 mg/L), Mo (0.0063 mg/L), Br (0.0025 mg/L), Cu (0.0016 mg/L), Zn (0.0063 mg/L), Co and I (0.0025 mg/L), Se (0.0010 mg/L), V (0.0003 mg/L), Na2EDTA.2H2O (2.5 mg/L), Na2SiO3.9H2O (10.0 mg/L), NaNO3 (0.27 mg/L), KH2PO4 (0.14 mg/L), K2HPO4 (0.18 mg/L), Thiamine (75.0 µg/L), B12 (1.0 µg/L), Biotin (0.75 µg/L); hardness: 180 mg/L expressed as CaCO3 and the pH: 7.7 ± 0.3
- Culture medium different from test medium: no
- Intervals of water quality measurement: pH and dissolved oxygen were measured at the beginning and at the end of the test, for the limit concentration and the control. The temperature of the medium was measured continuously in a temperature control vessel, beginning at the start of the test.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours photoperiod daily

EFFECT PARAMETERS MEASURED
Immobility was assessed at 24 and 48 hours.

VEHICLE CONTROL PERFORMED: not applicable

RANGE-FINDING STUDY
- Test concentrations: WAFs prepared at loading rates of 1.0 and 10 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

MEASURED CONCENTRATIONS
Samples taken from the control and all test concentrations were analysed. The test material was not detected in any of the samples. Consequently, the filter residue was analysed. The result demonstrated the presence of the test material during preparation of the test solutions.

IMMOBILITY
No immobility was observed in the control and at any of the concentrations tested.

Validity criteria fulfilled:

yes

Conclusions:

The 48h-EL50 for Daphnia magna exposed to the test material was beyond the range of concentrations tested, i.e. exceeded a loading rate of 100 mg/L.

Executive summary:

The toxicity of the test material to aquatic invertebrates was investigated in a study which was conducted in accordance with the standardised guideline OECD 202, under GLP conditions.

The test material was not completely soluble in test medium at the loading rates initially prepared.

A combined limit/range-finding test was performed. Water Accommodated Fractions (WAFs) were individually prepared at loading rates of 1.0, 10 and 100 mg/L and used as test concentrations.

Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to a WAF prepared at a loading rate of 100 mg/L, in a limit test. In addition ten daphnids per group (5 per replicate, duplicate) were exposed to WAFs prepared at loading rates of 1.0 and 10 mg/L in the combined range-finding test. 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.  

No immobility was observed in the control and at any of the concentrations tested.

Samples taken from the control and all test concentrations were analysed. The test material was not detected in any of the samples. Consequently, the filter residue was analysed. The result demonstrated the presence of the test material during preparation of the test solutions.  

In conclusion, the 48h-EL50 for Daphnia magna exposed to the test material was beyond the range of concentrations tested, i.e. exceeded a loading rate of 100 mg/L.

The study met the acceptability criteria prescribed by the study plan and was considered valid.

Description of key information

The 48h-EL50 for Daphnia magna exposed to the test material was beyond the range of concentrations tested, i.e. exceeded a loading rate of 100 mg/L.

Additional information

The toxicity of the test material to aquatic invertebrates was investigated in a study which was conducted in accordance with the standardised guideline OECD 202, under GLP conditions. The study was awarded a reliability score of 1 in accordance with the criteria set forth by Klimisch et al. (1997).

The test material was not completely soluble in test medium at the loading rates initially prepared.

A combined limit/range-finding test was performed. Water Accommodated Fractions (WAFs) were individually prepared at loading rates of 1.0, 10 and 100 mg/L and used as test concentrations.

Twenty daphnids per group (5 per replicate, quadruplicate) were exposed to an untreated control and to a WAF prepared at a loading rate of 100 mg/L, in a limit test. In addition ten daphnids per group (5 per replicate, duplicate) were exposed to WAFs prepared at loading rates of 1.0 and 10 mg/L in the combined range-finding test. 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.  

No immobility was observed in the control and at any of the concentrations tested.

Samples taken from the control and all test concentrations were analysed. The test material was not detected in any of the samples. Consequently, the filter residue was analysed. The result demonstrated the presence of the test material during preparation of the test solutions.  

In conclusion, the 48h-EL50 for Daphnia magna exposed to the test material was beyond the range of concentrations tested, i.e. exceeded a loading rate of 100 mg/L.

The study met the acceptability criteria prescribed by the study plan and was considered valid.