2,6-diisopropylnaphthalene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Sept./Oct. 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Remarks:

basic data given, accepable for assessment

Qualifier:

according to guideline

Guideline:

other: DIN 38412 part 9 (Determination of the inhibitory effect of aqueous constituents on green algae: Scenedesmus cell multiplication inhibition test)

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

(88/302/EEC, May 30, 1988)

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

(June 07, 1984)

Deviations:

yes

Remarks:

: only 2 replicates for test concentrations and for controls, no data and evaluation for validity criteria acc. to OECD TG 201

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

- Only analytics of stock solution (saturated aqueous solution): see below

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The saturated stock solution (water-accommodated fraction) was prepared by mechanically stirring of a 500 µg DIPN per 1 L medium
for 48 h followed by separation of the insoluble material from the water phase using pre-conditioned glass fiber filter.
The stock solution was diluted with dilution water to the desired concentration.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source (laboratory, culture collection): own culture
- Age of inoculum (at test initiation): 3 day old preculture
- Method of cultivation: no data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

pH:

8.8 - 9.8

Nominal and measured concentrations:

measured concentration of stock solution: 0.19 mg/L (preparation see under "Details on test solutions")
test solutions: 80, 75, 70, 65, 60, 55, 50, and 40% dilutions of stock solution

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Initial cells density: 0.002 (absorbance at lamba = 578 nm)
- Control end cells density: 0.267 (absorbance at lamba = 578 nm)
- No. of organisms per vessel: initially approx. 10,000 cell/mL
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2

GROWTH MEDIUM
- Standard medium used: yes (according to DIN 38412 part 9)

OTHER TEST CONDITIONS
- Test conditions: according to DIN 38412 part 9

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: absorbance at lambda = 578 nm:

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 0.94 - 1.1

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: only stock solution was analysed; effect concentration is 80% of stock solution concentration

Details on results:

- Exponential growth in the control (for algal test): yes
- Effect concentrations exceeding solubility of substance in test medium: no

No inhibitory effect was observed up to DIPN concentrations of 80% of a saturated solution.

Validity criteria fulfilled:

not specified

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Principles of method if other than guideline:

Read-across to preceding entry:
Source substance: Bis(isopropyl)naphthalene [DIPN, mixture of isomers]
Reference: Voge/UBA/WaBoLu 1999_Algae

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: only stock solution was analysed; effect concentration is 80% of stock solution concentration

Details on results:

- Exponential growth in the control (for algal test): yes
- Effect concentrations exceeding solubility of substance in test medium: no

Description of key information

NOEC (72 h) > 0.15 mg/L (nominal); read-across

Additional information

No algae toxicity study concerning only 2,6-diisopropylnaphthalene (2,6-DIPN) was available.

Therefore data on toxicity towards algae using Bis(isopropyl)naphthalene (DIPN) were used in a read-across approach in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 for assessment of 2,6-diisopropylnaphthalene . 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 Vogel (1999) used for assessment of toxicity towards aquatic algae was performed according DIN 38412 part 9 which is similar to OECD Guideline 201. Therefore a stock solution of nominal 500 µg/L in test medium was prepared by stirring for 48 hours followed by separation of the insoluble material from the water phase using pre-conditioned glass fiber filter and diluted with test medium to the desired concentrations. One control and eight treatments from 80 % - 40% dilution of the stock solutions in two replicates were tested for 72 hours and the algal cell density photometrical determined. The concentration of the stock solution was analytically determine using GC resulting in a measured concentration of 0.19 mg/L.

After 72 h the NOEC for DIPN was determined as > 0.15 mg/L based on measured concentrations (80 % dilution of analytical determined stock solution).