2,6-diisopropylnaphthalene

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:

14 Feb - 20 April 2012

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

no detailed analysis of the WAF

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Principles of method if other than guideline:

closed system

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
The Water Accommodated Fractions (WAFs) for the Range-Finding- and Definite Daphnia-Test with Bis-(isopropyl)naphthalene were prepared by
stirring various amounts of the test item in Daphnia-medium for 24 h with magnetic stirrers.
The WAFs were prepared in closed 2 L decanters. The test loading rates of Bis-(isopropyl)naphthalene were weighed in weighing scoops that
afterwards were placed into the decanters. The decanters were then filled with Daphnia medium and closed immediately.
The mixing was carried out at a speed that was slow enough not to cause dispersion or emulsification of the undissolved fraction of the test item.
To ensure this, the vortex developed at the surface by stirring was set at ~ 10 % of the water depth. After stirring for 24 h the WAFs were allowed
to stand for 1 h before use to facilitate phase separation and were then transferred directly into the test vessels, i.e. 50 mL glass vessels.
The test vessels were closed with ground-in glass stoppers directly after the transfer.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain: Clone 5
- Source: German Envirinmental Ministry
- Age at study initiation: <= 24 h
- Cultivation in a climate controlled room (light/dark = 14 h/10 h; illumination: Fluorescent tubes)
- Type and amount of food: Algae (Desmodesmus subspiccatus)
- Feeding during test: none

ACCLIMATION
- Acclimation period:
- Acclimation conditions (same as test or not):
- Type and amount of food: Algae (Desmodesmus subspiccatus)
- Feeding frequency:
- Health during acclimation (any mortality observed):

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

no data

Test temperature:

20°C +/- 2°C

pH:

8.0 -8.3 (measured at 0, 24, and 48 h)

Dissolved oxygen:

7.9 - 8.4 mg/ml (measured at 0, 24, and 48 h)

Salinity:

no data

Nominal and measured concentrations:

Range finding test: WAF (Water accommodated fraction) in test medium, 1.0, 10.0, 100 mg/L nominal

TOC at 0 h at 48 h:
=====================================
Control: 0.8 mg/L 0.3 mg/L
1 mg/L: 0.7 mg/L 0.3 mg/L
10 mg/L: 0.7 mg/L 0.4 mg/L
100 mg/L: 0.8 mg/L 0.4 mg/L
======================================
TOC-Analytik (± 0,1 mg/L) during range-finding (Note Aniol 09 April 2014)

Definitive test: WAF (Water accomodated fraction) in test medium, 1.0, 2.5, 5.0, 10, and 25 mg/L nominal.

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 ml glass vessels, closed with ground-in glass stoppers, test volume 50 mL
- Type: closed
- Aeration: none
- Renewal rate of test solution: - static (range finding test),
- semi static, renewal of test solution after 24 h (definite test)
- No. of organisms per vessel: 5
- No. of vessels per concentration and control (replicates): 2 (range finding test), 4 (definitive test)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised water
- Total organic carbon: no data
- Chlorine: no data
- Alkalinity: 0.8 mmol/l
- Na/K ratio: 10:1
- Ca/Mg ratio: 4:1
- Conductivity: no data
- Culture medium different from test medium: no
- Intervals of water quality measurement: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light/ 8 h dark (fluorescent tubes)
- Light intensity: no data

EFFECT PARAMETERS MEASURED: Immobilised daphnia, immobilised daphnia that were trapped at the surface of the water, daphnia that were not
immobilised but trapped at the surface of the water, daphnia that were not immobilised but weak and were observed mostly at the bottom of the test vessel, number of carapace moults.
The observations were made at 0 h, 24 h and 48 h.

TEST CONCENTRATIONS
- Preparation of test material: The test item Bis-(isopropyl)naphthalene is a liquid poorly soluble in water comprising volatile components. To avoid
adverse physical effects of undissolved or emulsified test material on the animals, the test was carried out with aqueous extracts
(WAF = Water Accommodated Fraction) at various loading rates in Daphnia-medium.
- Range finding study: with concentrations 1, 10, 100 mg/L
- Test concentrations (definitive test): 1, 2.5, 5, 10, 25 mg/L (due to the results of the range finding test)

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

1.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: derived from the result of immobilisation (20 %) at the loading rate of 1.0 mg/L

Key result

Duration:

48 h

Dose descriptor:

EL10

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: from dose-response curve at 1 mg/L minus 10% mobility in control.

Duration:

48 h

Dose descriptor:

other: EL90

Effect conc.:

ca. 3.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Mortality of control: 1 of 20 animals after 48 h
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no data

Reported statistics and error estimates:

Determination of the EL50 (EL = Effective Loading) of the immobilisation rate of the Definite Test was accomplished using Probit-analysis
(Finney-method, lognormal distribution; confidence limit 95 %, significance level: 0.05).

Immobilisation rate in dependence of time and loading rate, number of carapace moults, and number of living animals trapped at the surface

[number per total animals, %], (excerpt from original report).

Control

1 mg/L

2.5 mg/L

5 mg/L

10 mg/L

25 mg/L

Num-ber

[%]

Num-ber

[%]

Num-ber

[%]

Num-ber

[%]

Num-ber

[%]

Num-ber

[%]

Immobilisation 0 – 24 h start

0/20

0

0/20

0

0/20

0

0/20

0

0/20

0

0/20

0

Immobilisation 0 – 24 h end

0/20

0

0/20

0

2/20

10

19/20

95

13/20

65

15/20

75

Immobilisation 24 – 48 h start

0/20

0

0/20

0

2/20

10

19/20

95

13/20

65

15/20

75

Immobilisation 24 – 48 h end

1/20

5

4/20

20

15/20

75

19/20

95

20/20

100

20/20

100

Moults 48 h

15/20

75

16/20

80

5/20

25

3/20

15

5/20

25

6/20

30

Living animals at the surface 48 h

0/20

0

0/20

0

0/20

0

0/20

0

0/20

0

0/20

0

Immobilisation: 20 % at 1 mg/L, 75 % at 2.5 mg/L, 95 % at 5 mg/L and 100 % at 10 mg/L, and 25 mg/L after 48 h.

Validity criteria fulfilled:

yes

Remarks:

No more than 10 % immobilisation of the Control daphnia. The dissolved oxygen concentration during the test should be >= 3 mg/L and must not be < 2 mg/L.

Description of key information

EL50 (48 h): 1.7 mg/L (nominal); read-across

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1.7 mg/L

Additional information

No short-term aquatic invertebrate toxicity study concerning only 2,6-diisopropylnaphthalene (2,6-DIPN) was available.

Therefore an acute study on Daphnia magna using Bis(isopropyl)naphthalene (DIPN) was used in a read-across in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 approach for assessment of the acute toxicity towards aquatic invertebrates of 2,6-DIPN. Bis(isopropyl)naphthalene (DIPN) is an isomeric mixture, which consists of seven isomers (1,3-, 1,4-, 1,5-, 1,6-, 2,6- and 2,7-DIPN).

The study from Aniol et al. (2012) used for assessment of acute toxicity towards aquatic invertebrates was performed under GLP conditions according to OECD Guideline 202 using five treatments from 1.0 - 25 mg/L (nominal loadings) prepared as water accommodated fractions. Twenty Daphnia divided into 4 replicates per treatment and control were tested in none aerated glass beakers. A semi-static test design with a medium exchange after 24 hours was used. Due to the very low solubility of Bis(isopropyl)naphthalene, no analytical determination using TOC was possible. All validity criteria stated in OECD Guideline 202 were fulfilled.

After 48 h the EL50 was determined as 1.7 mg/L based on nominal loadings.