dialkyl-methyldihydro-heteropolycycle

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:

2019-03-12 to 2019-09-16

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

other: OECD Series on Testing and Assessment, No. 23, "Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures"

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Quadruplicate samples from the freshly prepared test media of all test concentrations and the control were taken at the start of the test and at day 1.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentrations during the test period, quadruplicate samples from the aged test media of all test concentrations and the control were collected at day 1 (after 24 hours of exposure) and at the of the additional test beakers prepared for the analytical dose verification of each treatment.
All samples were adjusted to pH10 with 1 M sodium hydroxide solution before storage.
Samples of the solvent control were not taken since Tween 80 is interfering with the analytical method and would therefore not have been reasonably analysable.

Test solutions

Vehicle:

yes

Remarks:

Reconstituted water with Tween 80 at a concentration of 100 µL/L was used as solvent.

Details on test solutions:

An aqueous solution of dialkyl-methyldihydro-heteropolycycle in test media with a concentration (nominal: 110 mg/L) as close to saturation as possible (referred to as a ´stock solution´) was obtained first. This stock solution and its dilutions of 1:2, 1:4, 1:8 and 1:16 were prepared for test start and at the renewal period after 24 hours. Samples of the freshly prepared solutions for analytical dose verification were taken before Tween 80 was added to each test concentration at 100 µL/L, after which the test organisms were introduced for testing. Additionally, a solvent control (100 µL Tween 80/L) and a control were tested. These concentrations refer to nominal concentrations of 110, 55, 27.5, 13.75 and 6.875 mg test item/L.

The test item is not well soluble in test medium. To avoid physical effects of undissolved test item on the daphnids, no concentrations far above the solubility limit of the test item in test water was tested.
Therefore, a ´stock solution´ (110 mg/L) of dialkyl-methyldihydro-heteropolycycle in test medium was prepared by mixing 119.5 and 117.1 mg test item into 1086.36 and 1064.55 mL test water at test start and 112.1 and 112.8 mg test item into 1019.1 and 1025.45 mL test water on Day 1. The test medium was stirred with an excess of dialkyl-methyldihydro-heteropolycycle in a vessel for 24 hours. Afterwards the test medium was allowed to settle until phase separation for 1 hour This ´stock solution´ was withdrawn from a tap at the center of the vessel, after first flushing the tap and tubing with a small aliquot, and then mixed with test medium to produce the desired dilutions of 1:2, 1:4, 1:8 and 1:16.
The test media were prepared just before introduction of the daphnids (= start of the test) and test medium renewal on Day 1.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

Species: Daphnia magna (Straus), clone 5
Age at Test Start: From 3.00 to 22.50 hours old Sex: Female
Origin: The daphnids introduced in the test were taken from ibacon's in house laboratory culture.
Breeding Conditions: The daphnids were bred in the laboratories of ibacon under similar temperature and light conditions as used in the test. The cultivation of the parental daphnids was performed in Elendt M4 medium. The test organisms were not first brood progeny. The daphnids in the stock culture were fed at least on all working days with green algae (Desmodesmus subspicatus) freshly grown in the laboratories of ibacon.

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

Water Hardness: 2.5 mmol/L (= 250 mg/L) as Calcium Carbonate

Test temperature:

20 °C at test start;
19 - 20 °C at test end

pH:

7.9 to 8.0 in the freshly prepared media;
7.9 in the aged test media; and thus the pH-value did not vary by more than 1.5 units

Dissolved oxygen:

8.8 to 9.1 mg/L in the freshly prepared media;
8.7 to 9.0 mg/L in the aged test media

Nominal and measured concentrations:

Test Concentrations:
An aqueous solution of dialkyl-methyldihydro-heteropolycycle in test media with a concentration (nominal: 110 mg/L) as close to saturation as possible (referred to as a ´stock solution´) was obtained first. This stock solution and its dilutions of 1:2, 1:4, 1:8 and 1:16 were prepared for test start and at the renewal period after 24 hours. These concentrations refer to nominal concentrations of 110, 55, 27.5, 13.75 and 6.875 mg test item/L.
Samples of the freshly prepared solutions for analytical dose verification were taken before Tween 80 was added to each test concentration at 100 µL/L, after which the test organisms were introduced for testing.

The mean measured values of the freshly prepared media are:
151 μg test item/L in the WAF stock solution (SD = 14.2 μg test item/L)
78.5 μg test item/L in the 1:2 dilution of WAF stock solution (SD = 9.11 μg test item/L)
37.8 μg test item/L in the 1:4 dilution of WAF stock solution (SD = 0.71 μg test item/L)

The mean measured values of the 24 hours aged media are:
82.9 μg test item/L in the WAF stock solution (SD = 9.10 μg test item/L)
34.4 μg test item/L in the 1:2 dilution of WAF stock solution (SD = 0.96 μg test item/L)
26.9 μg test item/L in the 1:4 dilution of WAF stock solution (SD = n.a.)

Details on test conditions:

Test Environment: Controlled environment room
Measurement of pH, Dissolved Oxygen and Water Temperature: The water temperature, pH-values and the dissolved oxygen concentrations were determined in all freshly prepared and aged test media of each treatment group.
Water Temperature: 19.5 to 20.2 °C in the freshly prepared media; 19.3 to 19.5°C in the aged test media
pH-Values: 7.9 to 8.0 in the freshly prepared media; 7.9 in the aged test media; and thus the pH-value did not vary by more than 1.5 units
Dissolved Oxygen Concentration: 8.8 to 9.1 mg/L in the freshly prepared media; 8.7 to 9.0 mg/L in the aged test media
Light Regime: 16 h light : 8 h dark
Light Intensity: The light intensity was 440 to 530 lux (measured once during the test).

Reference substance (positive control):

yes

Remarks:

The results of the reference test indicate that the sensitivity of the daphnids was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

>= 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 3

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

> 110 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 48 hours of exposure no immobilisation of the test animals was observed in the control and up to and including the highest test item concentration of nominal 110 mg test item/L. In the solvent control, one animal was immobile after 48 hours

Results with reference substance (positive control):

In the most recent test with the reference item potassium dichromate the EC50 after 24 hours was determined to be 0.932 mg test item/L, indicating that the sensitivity of the Daphnia was consistent with the level proposed by the OECD 202 guideline (EC50-24 h between 0.6 and 2.1 mg potassium dichromate/L).

Reported statistics and error estimates:

No statistical analysis was performed.
The EC50 could not be quantified due to the absence of toxicity of the test item and were determined to be higher than the highest test concentration. The NOEC and the LOEC were determined directly from the raw data.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

Control Immobilisation Rate was 0 % and furthermore no daphnid showed signs of disease or stress. Dissolved Oxygen Concentration was above or equal 8.7 mg O2/L in the control and test vessels at the end of the test.

Conclusions:

The toxic effect of the test item dialkyl-methyldihydro-heteropolycycle to Daphnia magna was assessed in a semi-static concentration-response test. The 48-hour NOEC was determined to be ≥ 110 mg test item/L. The 48-hour LOEC was determined to be >110 mg test item/L and the 48-hour EC50 value was determined to be > 110 mg test item/L.
The initial concentrations and the maintenance of the exposure concentrations during the test were verified in the analytical part. All reported results refer to nominal concentrations (loading rate) since a supersatured stock solution via a water accommodated fraction was prepared.

Executive summary:

The toxic effect of the test item dialkyl-methyldihydro-heteropolycycle to Daphnia magna was assessed in a semi-static concentration-response test. The 48-hour NOEC was determined to be ≥ 110 mg test item/L. The 48-hour LOEC was determined to be >110 mg test item/L and the 48-hour EC50 value was determined to be > 110 mg test item/L.

The initial concentrations and the maintenance of the exposure concentrations during the test were verified in the analytical part. All reported results refer to nominal concentrations (loading rate) since a supersatured stock solution via a water accommodated fraction was prepared.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.