DODECANEDIOIC ACID, 1,12-BIS(2-OCTYLDODECYL) ESTER

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:

From 3 Feb 2020 to 6 Feb 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Details on sampling:

At approximately 24-hour intervals after the start of the incubation period, pre determined volumes of test media (1.0 mL at 24 hours and 0.5 mL at 48 and 72 hours) were removed from each incubated test vessel, and transferred to individually identified cell counting vials. The contents of each vial were diluted to a 10 mL final volume with an electrolyte solution. The cell density of the vial contents was then determined using a particle counter (Z2 Coulter Counter®).

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

The axenic strain of Raphidocelis subcapitata (CCAP 278/4) was obtained from a concentrated liquid slope culture from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd., Oban, UK.
On receipt from the CCAP, the slope culture was stored in the fridge at 2-8°C. A typical shelf life for each slope was 8 months, after which the slopes were discarded.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

The incubator temperature was set within the range 21 to 24°C and maintained within ± 2°C for the duration of the test. The temperature was recorded continuously using a digital thermometer.

pH:

At test initiation the pH of the control was 7.99 and the pH of the test was 8.00 in solutions with algae. The pH in the control and test vessels at the end of the test were between 8.33 – 9.57.
Refer to table 1

Details on test conditions:

TEST SYSTEM
The test vessels were sterile autoclaved glass 250 mL Erlenmeyer (conical) flasks, into which 100 mL of the appropriate control or test media was added. Sterile foam bungs were used to cover the top of the vessels.
Each test and control vessel was inoculated with sufficient Raphidocelis subcapitata cells to achieve a starting algae cell concentration of 1 × 104 cells/mL. An additional inoculated vessel was prepared for the control and each test concentration for initial water quality analysis.

At approximately 24-hour intervals after the start of the incubation period, pre determined volumes of test media (1.0 mL at 24 hours and 0.5 mL at 48 and 72 hours) were removed from each incubated test vessel, and transferred to individually identified cell counting vials. The contents of each vial were diluted to a 10 mL final volume with an electrolyte solution. The cell density of the vial contents was then determined using a particle counter (Z2 Coulter Counter®).

All flasks were loosely-capped and incubated in a temperature and light controlled incubator. The vessels were placed on an orbital shaker (ca 100 rpm) under conditions of constant light (4440 to 8880 Lux), using florescent lights, emitting light across the visible portion of the spectrum (400 - 700 nm). The light intensity within the test area was monitored at 0, 24, 48 and 72 hours over 5 areas within the test area.
At the start of the test, the pH of freshly prepared test media was determined. The pH in each test vessel was also determined at the end of the test.
The incubator temperature was set within the range 21 to 24°C and maintained within ± 2°C for the duration of the test. The temperature was recorded continuously using a digital thermometer.

Reference substance (positive control):

not required

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The effects of Dioctyldodecyl Dodecanedioate on the growth of the unicellular green alga, Raphidocelis subcapitata, were determined during a 72-hour growth inhibition toxicity test conducted in accordance with OECD Chemicals Testing Guideline No. 201 Alga, Growth Inhibition Test (adopted 23 March 2006) (Annex 5 corrected 28 July 2011).

Given the analytical challenges presented by this test substance the level of solubility was not known. In order to test at the limit of solubility, the Water Accommodated Fractions (WAFs) method recommended for UVCBs in the above guidance was used to saturate the media with the test substance.
As there was no valid analytical method available to measure the test substance concentration at the time of testing, the results were based on nominal loading rates.
Based on nominal loading rates, the 72-hour EyC50 and ErC50 values were calculated to be >100 mg/L.

The corresponding NOEL values for yield and specific growth rate after 72 hours were 100 mg/L.

All validity criteria were met therefore the test was considered valid.

Conclusions:

The effects of Dioctyldodecyl Dodecanedioate on the growth of the unicellular green alga, Raphidocelis subcapitata, were determined during a 72-hour growth inhibition toxicity test conducted in accordance with OECD Chemicals Testing Guideline No. 201 Alga, Growth Inhibition Test (adopted 23 March 2006) (Annex 5 corrected 28 July 2011).
Based on nominal loading rates, the 72-hour EyC50 and ErC50 values were calculated to be >100 mg/L.

The corresponding NOEL values for yield and specific growth rate after 72 hours were 100 mg/L.

All validity criteria were met therefore the test was considered valid.

Executive summary:

Product should not be classified according to CLP criteria for Acute or Chronic Hazards to the environment.

Description of key information

Based on result product should not be classified according to CLP criteria for Acute or Chronic Hazards to the environment.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L