Isooctadecyl pivalate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 - 18 Jun 2015

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted in accordance with current guidelines and GLP compliance.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

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)
- Method: the test loading was prepared by applying the Water Accommodated Fraction (WAF) approach according to the OECD guidance documents No. 23
- Eluate: 200 mg test item were transferred into a 2 L sterile glass flask with a drain port at the bottom via a Teflon weighing boat.
The flask was brought to a volume of about 2 L with sterile growth medium to obtain the required nominal loading of 100 mg/L. The test media was stirred slowly to prevent bubble, foam or emulsion formation using a star shape magnetic stirring bar for at least 48 h at room temperature (~20°C).
After stirring the vessel was left to settle for at least 2 hours or until a separation of the phases could be observed. Then the saturated lower aqueous phase was taken out of the drain port. The first fraction 0 - 200 mL was discarded. The eluate was checked for irregularities such as foam formation and the clear eluate was used for the growth tests. All work was conducted under sterile conditions (clean bench) using sterile equipment.
- Controls: medium only, treated like described above.
- Evidence of undissolved material (e.g. precipitate, surface film, etc): at start of the growth test: none

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Other name: Raphidocelis subcapitata, formerly known as Selenastrum capricornutum
- Source (laboratory, culture collection): laboratory culture; Origin: SAG, Culture Collection of Algae at Pflanzenphysiologisches Institut of the University at Göttingen, Albrecht von Haller Institut, Untere Klarspüle 2, D-37073 Göttingen, Catalog No 61.81 SAG.
- Age of inoculum (at test initiation): 3 days
- Method of cultivation: stock culture medium Bringmann and Kühn (1980), Water Research 14(3), 231-241.

ACCLIMATION
- Acclimation period: 3- day pre-test in OECD 201 test medium under test conditions
- Culturing media and conditions: same as test
- Any deformed or abnormal cells observed: no

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

No.

Hardness:

Mg 0.059 mM, Ca 0.122 mM equivalent to total hardness of 18.1 mg/L of CaCO3

Test temperature:

Temperature was stable at 22.0 °C during the test in the culture media

pH:

The pH of the controls stayed almost stable during the test (8.32 at test start and a mean value of 8.39 at test end).
In the test cultures the initial pH was 8.61 and the mean pH at the end of the test was 8.43.

Nominal and measured concentrations:

100 mg/L loading

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL conical glass flasks covered with air-permeable silicone-sponge caps.
- Fill volume: filled with 100 mL medium
- Aeration: no
- Initial cells density: 10 000 cells/mL
- Control end cells density: 1 729 000 cells/mL
- No. of vessels per concentration (replicates): 8
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: yes (OECD 201)

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: no
- Photoperiod: continuous illumination
- Light intensity and quality: 92.37 to 99.42 µmol m-2 s^-1 , OSRAM “day light” fluorecence tubes

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable - Limit test
- Range finding study: no
- Test concentrations: 100 mg/L loading in definitive test

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

>= 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL10

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none
- Unusual cell shape: no
- Colour differences: no
- Flocculation: no
- Adherence to test vessels: no
- Aggregation of algal cells: no
- Other: -
- Any stimulation of growth found in any treatment: -
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no
- Effect concentrations exceeding solubility of substance in test medium: -

Results with reference substance (positive control):

- Results with reference substance valid? yes
- EC50: 3,5-Dichlorophenol ErC50 2.58 mg/L (95% confidence limits: 2.48–2.68 mg/L)

Reported statistics and error estimates:

Normal distribution (Shapiro-Wilk’s Test) and variance homogeneity (Levene’s test) requirements were fulfilled. Thus, a parametric multiple test was advisable. The Student-t test for Homogenous Variances was chosen to test the difference concentration. Growth rate and yield of the treatment not significantly different from control (p < 0.05).

Table:   Percent inhibition of growth rate and yield compared to controls after 72 hours

Nominal loading [mg test item/L]	% Inhibition of growth rate	% Inhibition of yield
Control	0.0	0.0
100	1.999	9.463

Table:   Effective loading of the test item for the exposure of Pseudokirchneriella subcapitata for 72 h.

Parameter		EL50[mg/L]	EL10[mg/L]		NOEL [mg/L]
Growth rate (r)	Value	> 100	> 100		≥ 100.
Yield (y)	Value	> 100	> 100		≥ 100

Validity criteria fulfilled:

yes

Conclusions:

No growth inhibition could be observed for P. subcapitata due to the test item within a test period of 72 hours under static conditions at a concentration of 100 mg/L. The NOEL values for both growth rate and yield are reported as equal to or higher than 100 mg/L and the EL50 values were not calculated as inhibition for both growth rate and yield was less than 50 % compared to controls (EL50 > 100 mg/L).

Executive summary:

A limit test was performed at the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) to determine the toxicity of the test item Isostearyl neopentanoate on the growth of the unicellular fresh water green alga Pseudokirchneriella subcapitata.The algae were exposed under static conditions for a test period of 72 hours in accordance with the OECD guideline 201. Eight replicates were used for the control (test medium only) and eight replicates for the test loading.

The test item was prepared as eluate with sterilised OECD 201 growth medium by applying the Water Accommodated Fraction (WAF) approach according to the OECD guidance documents No. 23. The one nominal loading tested was 100 mg/L. The test item concentration of the UVCB was not analytically verified and thus the assessment was based on the nominal loading.

There was no negative loading-dependent effect on the growth (yield or growth rate) of P. subcapitata. The ErC50 was equal to or higher than 100 mg/L loading.

Table: Effective nominal loading after 72 h exposure to P. subcapitata

Parameter	Istostearyl neopentanoate	EL50[mg/L]	EL10[mg/L]	NOEL [mg/L]
Yield (y)	Value (95% confidence limit)	> 100	> 100	≥ 100
Growth rate (r)	Value (95% confidence limit)	> 100	> 100	≥ 100

Description of key information

No effects up to the water solubility limit (1.0 - 27 µg/L, mean: 11.7 µg/L; OECD 201)

Additional information

A limit test was performed to determine the toxicity of the test item Isooctadecyl pivalate (CAS 58958-60-4) on the growth of the unicellular fresh water green algae Pseudokirchneriella subcapitata. The algae were exposed under static conditions for a test period of 72 hours in accordance with the OECD guideline 201 (GLP). Eight replicates were used for the control (test medium only) and the test loading.

The test item was prepared as eluate with sterilised OECD 201 growth medium by applying the Water Accommodated Fraction (WAF) approach according to the OECD guidance documents No. 23. The one nominal loading tested was 100 mg/L. The test item concentration of the UVCB was not analytically verified and thus the assessment was based on the nominal loading.

There was no negative loading-dependent effect on the growth (yield or growth rate) of P. subcapitata. The ErL50 (72 h) was > 100 mg/L and the NOELR (72 h) was derived to be ≥ 100 mg/L.