Polysodium 4-amino-5-hydroxy-3-[{8-hydroxypolysulfonato-7-[{sulfonato-4-[(sulfonatophenyl)diazenyl]phenyl}diazenyl]-2-naphthyl}diazenyl]-6-[(4-nitro-sulfonatophenyl)diazenyl]naphthalenepolysulfonate

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:

25 October to 1 November 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Data have been generated according to current internationally recognised study guidelines and in accordance with GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Instrument: High-performance liquid chromatograph, SHIMADZULC-201OAHT (Equipped with UV-VIS detector)Column: L-column2 ODS (150 mm x 2.1 mm I.D. particle size 5 µm, Chemicals Evaluation and Research Institute, Japan)Column temp: 40°CEluent: A (25%) : Methanol, B (75%)Flow rate: 5mmol/L ammonium acetate solutionWavelength: 590nmInjection volume: 20µL

Vehicle:

no

Test organisms (species):

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

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.1-22.5°C

pH:

7.8-7.9

Nominal and measured concentrations:

Nominal concentrations of 100, 32, 10, 3.2, 1.0, 0.32 and 0.10 mg/L (a geometric series with a factor of √10)Control:The medium without the test item

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

18 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

At the start of exposure, test solutions of all exposure levels were dose-dependently navy-blue and clear.  At the end of exposure, the appearances of test solutions in 100 -0.32 mg/L levels were dose-dependently navy-blue, those of 1.0 -0.10 mg/L levels were green, due to the algae growth. Furthermore, the test solution in 3.2 mg/L level wasn't green, due to the algae growth.  However, the cells were visually confirmed. The solution of control was colorless and clear at the start of exposure, and it was green at the end of exposure due to the algal growth.

 

The measured concentration of the test item in the test solutions were 0.10 -110 mg/L at the start of exposure (100 -109% of the nominal concentration). The concentrations at the end of the exposure were 0.10 -110 mg/L (103 -112% of the nominal concentration). The measured concentrations of the test item were kept within ± 20% of the nominal concentration.

 

In 100 mg/L level, growth inhibition was found remarkably during the exposure.  In 32mg/L level, growth inhibition was found remarkably until 48 hours, and then algal grew more than 100mg/L level.  In 10mg/L level, although growth inhibition was found, the algal growth after 24 hours of the exposure was logarithmic.  The algal growth in 3.2 mg/L level was logarithmic, although growth inhibition was found.  Other exposure levels were same as the control level.

 

The following results of cell observation were based on the comparison with the control.

In 100 mg/L level, a lot of small cells were observed.  In 32mg/L level, almost al of cells were bloat and a lot of small aggregated cells were observed. In 10 and 3.2 mg/L levels, some cells were bloat. The conditions of cells in the other exposure levels were same as the control.  In the control, the condition of cells was not abnormal.

 

On the growth rate, there were statistical differences in 3.2 and 10 mg/L exposure levels.  By the results in statistical analysis and cell observation showed above, NOEC based on growth rate was estimated at 1.0 mg/L. 

 

This study was conducted in order to estimate the effect on the test organisms under the solubility of the test item in medium.  In the results of preliminary study, the test solution in 100 mg/L level was navy-blue and clear.  The preliminary study with some exposure levels including normal and reduced volumes of test solution so that the effect of light attenuation was decreased was conducted in order to confirm the effect on the algal growth by colored solution.  As the results, in 100 mg/L level whose test solution was the deepest colored, the growth inhibition of normal and reduced volumes of test solutions were the same.   Moreover, the growth inhibitions in the other exposure levels were almost the same.  Therefore it was considered that no effect on algal growth was found by coloring.  In the definitive study was conducted with the normal volume of test solution (100 mL).   As a result, E_rC₅₀ was 18 mg/L and NOEC was 1.0mg/L. 

 

The concentrations of the test item in the test solutions were kept within ± 20% of those at the start of exposure.  The environmental conditions were within the suitable range.    

Validity criteria fulfilled:

yes

Conclusions:

The substance is considered to inhibit the growth of algae. The ErC50 is 18 mg/L

Executive summary:

The Growth Inhibition to Algae (Pseudokirchneriella subcapitata) has been assessed according to the OECD 201 test guideline in accordance with GLP with analytical monitoring at the start and end of exposure by HPLC. The analysis demonstrated that the concentration remained consistent at the start to end of exposure. The substance is a coloured substance and forms a navy-blue solution. The substance has, however, been assessed at nominal and reduced volumes to confirm whether the growth inhibition was due to reduction in light intensity or true inhibition of growth. It was determined that the inhibition in growth was due to exposure of the substance rather than an effect of reduced light intensity. The ErC50 of the substance was determined to be 18 mg/L.

Description of key information

The Growth Inhibition to Algae (Pseudokirchneriella subcapitata) has been assessed according to the OECD 201 test guideline in accordance with GLP with analytical monitoring at the start and end of exposure by HPLC. The analysis demonstrated that the concentration remained consistent at the start to end of exposure. The substance is a coloured substance and forms a navy-blue solution. The substance has, however, been assessed at nominal and reduced volumes to confirm whether the growth inhibition was due to reduction in light intensity or true inhibition of growth. It was determined that the inhibition in growth was due to exposure of the substance rather than an effect of reduced light intensity. The ErC50 of the substance was determined to be 18 mg/L and the NOEC was 1.0 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.8 mg/L

EC10 or NOEC for freshwater algae:

1 mg/L