Tar bases, coal, lutidine fraction

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:

Experimental start: 11 December 2015, Experimental completion: 01 March 2016, Report finalisation: 04 April 2016

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)

Version / remarks:

2011

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Samples were taken at 24, 48, 72 and 96 hours to determine the cell densities using a Coulter Multisizer Particle Counter. Samples were taken from the control and each test group at the start of the experiment and from pooled replicates at 96 hours for quantitative analysis. All samples were stored frozen immediately after sampling. Duplicate samples were taken at 0 and 96 hours and stored frozen for further analysis if necessary.

Vehicle:

no

Details on test solutions:

Nominal amounts of test item (100 and 32 mg) were each separately dissolved in culture medium and the volumes adjusted to 1 liter to give 100 and 32 mg/L stock solutions, respectively. A series of dilutions was made from these stock solutions to give further stock solutions of 10, 3.2 and 1.0 mg/L. The test media were prepared just before inoculation with algal suspension. An aliquot of 900 mL of each of the test concentrations was separately inoculated with 6.7 mL of algal suspension to give a nominal cell density of approximately 5000 cells/mL.

Test organisms (species):

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

Details on test organisms:

Liquid cultures of Pseudokirchneriella subcapitata were obtained from the Culture Collection of Algae and Protozoa (CCAP), SAMS Research Services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland. Master cultures were maintained in the laboratory by the periodic replenishment of culture medium. The master cultures were maintained in the laboratory under constant aeration and constant illumination at 21 ± 1 °C.
Prior to the start of the test sufficient master culture was added to approximately 100 mL volumes of culture media contained in conical flasks to give an initial cell density of approximately 1000 cells/mL. The flasks were plugged with polyurethane foam stoppers and kept under constant agitation by orbital shaker (100 – 150 rpm) and constant illumination at 24 ± 1 °C until the algal cell density was approximately 10000 - 100000 cells/mL.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Hardness:

15 mg/L as CaCO3

Test temperature:

24 ± 1 °C

pH:

Adjusted to 7.5

Dissolved oxygen:

Not available

Salinity:

Not applicable

Conductivity:

Not available

Nominal and measured concentrations:

Nominal: 0, 1, 3.2, 10, 32 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL Erlenmeyer flasks made of glass, filled with 100 mL test medium
- Type: test flasks were plugged with a polyurethane foam bung
- Aeration: not applicable
- Initial cells density: 5000 cells/mL
- Control end cells density: 872000 cells/mL (mean at 72 hours)
- No. of vessels per concentration (replicates): three
- No. of vessels per control (replicates): six

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstitutet test water (ASTM medium), analytical grade salts were dissolved in purified water
- No further information on water quality provided
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: 6908 lux (6700 to 7180), warm lighting (380-730 nm)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Determination of cell concentrations: [counting chamber; electronic particle counter; fluorimeter; spectrophotometer; colorimeter]
- Chlorophyll measurement:
- Other:

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Range finding study
- Test concentrations: 0.1 to 100 mg/L
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

potassium dichromate, tested twice a year. Results of the latest positive control test performed in December 2015 gave an ErC50 value of 1.5 mg/L, which is in the historical range of 0.82 to 1.5 mg/L obtained between 2010 and 2015.

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 87 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

31 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

34 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

23 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

2 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.3 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Results with reference substance (positive control):

Test result of most recent positive control with potassium dichromate: ErC50 = 1.5 mg/L, which is in the historic range from 0.82 to 1.5 mg/L

Validity criteria fulfilled:

yes

Conclusions:

A 96-hour algal growth inhibition test under static conditions produced a 72-hour ErC50 value of >87 mg/L and a 72-hour ErC10 of 23 mg/L.

Executive summary:

A study was performed to assess the effect of CA3490A on the growth of the green alga Pseudokirchneriella subcapitata in a 96-hour static test. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals (2006) No 201 (adopted 2006, corrected 2011) "Freshwater Alga and Cyanobacteria, Growth Inhibition Test". The experiment is considered relevant, adequate and conclusive.

Following a preliminary range-finding test, Pseudokirchneriella subcapitata was exposed to an aqueous solution of the test item at nominal concentrations of 1.0, 3.2, 10, 32 and 100 mg/L (three replicate flasks per concentration) for 96 hours, under constant illumination and shaking at a temperature of 24 ± 1 °C. Analysis of the test preparations at 0 hours showed measured test concentrations to range from 86% to 93% of nominal indicating that the test system had been correctly dosed. A slight decline in measured concentration was observed at 96 hours in the range of 74% to 81% of nominal. Given this decline in measured test concentrations it was considered appropriate to calculate the results based on the geometric mean measured test concentrations which were determined to be 0.80, 2.6, 8.6, 27 and 87 mg/L. Based on the results, the 72-hour ErC50 value was determined to be >87 mg/L, and the 72-hour ErC10 value was 23 mg/L.  

Description of key information

72-hour ErC50 >87 mg/L, green algae, Vryenhoef 2016 (OECD TG 201, GLP)

72-hour ErC10 = 23 mg/L, green algae, Vryenhoef 2016 (OECD TG 201, GLP)

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

23 mg/L