Disodium sebacate

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:

2009-10-22 to 2009-11-13

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

ISO 10253

Qualifier:

according to guideline

Guideline:

ISO 10253 (Water quality - Marine Algal Growth Inhibition Test with Skeletonema costatum and Phaeodactylum tricornutum)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Water accommodated fractions (WAF)
- Controls: untreated incubation medium

WAF: Individual preparation of WAFs by stirring appropriate amounts of the test substance in growth medium (according to ISO 14442:2006). The solutions were stirred with a spin-bar for 22 hours with a speed which formed a vortex one-third of the depth of the fluid content followed by standstill for about 1.5 hour.

Test organisms (species):

Skeletonema costatum

Details on test organisms:

TEST ORGANISM
- Common name: Skeletonema costatum
- Strain: NIVA-BAC 1
- Source: originally isolated from the Oslo fiord (1962)
- Method of cultivation: In the laboratory the algae were held at 15 ± 2 °C under continuous light from fluorescent tubes of universal natural white type. Sub-cultures were started twice to three times a week by transferring amounts of the growing culture to approx. 50 mL of fresh growth medium.

ACCLIMATION
- Acclimation period: 4 d (2009-11-6 to 2009-11-10)

- The culture was bought from Norsk Institut for Vannforskning (NIVA) in Oslo on 25.09.2009.
- The pre-culture used in this test was started at 25.09.2009 and incubated on an orbital shaker.
- The cell number was determined by microscope counting using a Palmer-Maloney counting slide.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

19.1 - 20.9 °C

pH:

5.1 - 8.4

Salinity:

34.4 per mill

Nominal and measured concentrations:

test substance concentrations nominal: 3.0, 10.0, 31.9, 100, and 320 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 ml flat-bottomed flasks
- Type: closed
- fill volume: 50 mL
- Initial cells density: 2000 cells/mL
- No. of vessels per concentration: 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used: natural seawater was used as basis for the growth medium. Nutrient enrichment according to ISO 10253.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Natural seawater from an unpolluted site at about 80 m depth in Byfiord was collected on 19.10.2009 from a tap at Akvamiljo

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continous light
- Light intensity and quality: > 50 pE/m2*sec-1
- Salinity (for marine algae): 0.0345%

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Flourescence (Turner designs, Model 10 flourimeter), excitation 340 nm, emission > 665 nm
- Samples were taken at the start of the study, after 24, 48, and 72 h
- samples of 5 mL were drawn off through a drain port near the bottom of the bottle

Reference substance (positive control):

yes

Remarks:

3.5-dichlorophenol

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

38.7 mg/L

Nominal / measured:

nominal

Conc. based on:

other: WAF (Water accommodated fraction)

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

3 mg/L

Nominal / measured:

nominal

Conc. based on:

other: WAF

Details on results:

A significant growth-stimulating effect was observed at the test concentration 3.0 mg/L WAF, which means that this concentration gave responses differing from the blank by showing a higher growth rate. This is why NOEC is stated as the highest test concentration without significant growth inhibition.
Concentrations above 3 mg/L led to growth inhibition with an interpolated EL50 of 38.7 mg/L.

Validity criteria fulfilled:

yes

Description of key information

A growth inhibiting effect was documented and an EL50 of 38.7 mg/L was determined (BASF SE, 2009).

Additional information

No data on aquatic toxicity with the salt disodium sebacate are available. Only data on the acid are available:

In 72 hour acute toxicity study, the cultures of Skeletonema costatum were exposed to sebacic acid at nominal concentrations of 3.0, 10.0, 31.9, 100, and 320 mg/L WAF under static conditions in accordance with the ISO 10253 (BASF SE, 2009). The determination of the EL50 based on the reduced growth rate in treated groups. The EL50 and NOEL values based on cell density was 38.7 and 3 mg/L, respectively.

However, according to ECHA guidance R7b effects can be extrapolated from the anion or cation, whichever has the most toxic effect, if no data are available on a salt.

If the effect is related to only one of the ions, the classification of the salt should use the effect concentration multiplied by the salt/ion molecular weight ratio.

The molecular weight ratio between salt and ion is 246 : 202 (1.22)

Based on this correction the EL 50 and NOEC for disodium sebacate in a growth inhibition study with marine Sketelonema costatum was determined to be 47.2 and 3.7 mg/L, respectively.