Disodium 1,5-dihydroxypentane-1,5-disulphonate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 08 NOVEMBER 2018 to 17 NOVEMBER 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

According to OECD 201 resp. EU C.3

Deviations:

yes

Remarks:

-temperature during pre-culture incubation was 22.6 – 24.3°C, not 21.0 - 24.0°C. As all validity criteria were met and exponential growth was observed in the blank control this was stated as uncritical!

Principles of method if other than guideline:

• The stock solutions to be autoclaved were autoclaved for 20 minutes instead of the required 15 minutes. This can be considered uncritical, as the goal of sterility is achieved.
• The pre-culture was prepared 5 days before the test start. As all validity criteria were met and exponential growth was observed in the blank control this was stated as uncritical.
• The temperature during pre-culture incubation was in the range 22.6 – 24.3°C, and therefore not in the desired range (21.0 - 24.0°C). As all validity criteria were met and exponential growth was observed in the blank control this was stated as uncritical.

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Disodium 1,5-dihydroxypentane-1,5-disulphonate

Cas Number:

7420-89-5

Molecular formula:

C5H10Na2O8S2

IUPAC Name:

Disodium 1,5-dihydroxypentane-1,5-disulphonate

impurity 1

Reference substance name:

Sodium sulfate

Cas Number:

7757-82-6

IUPAC Name:

Sodium sulfate

impurity 2

Reference substance name:

Sodium hydrogen sulfite

Cas Number:

7631-90-5

IUPAC Name:

Sodium hydrogen sulfite

Sampling and analysis

Analytical monitoring:

yes

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

The culture of Desmodesmus subspicatus was obtained in January 2016 by MBM Sciencebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen). The algae are kept as stock culture on solid agar at 2 - 8 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.

Study design

Total exposure duration:

72 h

Test conditions

Details on test conditions:

For each treatment, 200 mL of the respective test item solution was mixed with the necessary amount of algal pre-culture (0.397 mL) to achieve a cell concentration of 2.6 *103 cells/mL. For the blank control, 350 mL nutrient medium was used instead of test item solution and mixed with the necessary amount of algal pre-culture (0.497 mL). In this mixture, the pH-value was measured.
The real cell concentration at the beginning of the test was measured with an electronic particle counter in the blank control solution. This measured value was used as start cell concentration for all replicates.
Samples for the analytical determination were taken before addition of algal pre-culture.
The test vessels were filled with 45 ± 1 mL of the respective test solution and incubated open (covered with perforated plastic foil acting as a stopper) for 72 hours, shaken on an orbital shaker to keep the algae in suspension. Before the start of incubation and every 24 hours, the cell number was determined with an electronic particle counter. After the test, samples for the analytical determination were taken, afterwards the pH value in treatments and blank control was measured again.
At the end of the test, the treatments were examined microscopically in order to assess the appearance of the algae and detect abnormalities (e.g. caused by the exposure to the test item).
The content of DOC in the test vessels was measured at the start and at the end of the test.
For elimination of the algal cells before analytical determination at the end of the test, samples were centrifuged.

Reference substance (positive control):

yes

Remarks:

Potassium dichromate was used as positive control in a separate reference test.

Results and discussion

Effect concentrations

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.35 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Parameter Value 95% confidence interval
NOEC (Growth Rate)72 h < 0.09 mg/L --
NOEC (Yield) 72 h < 0.09 mg/L --
LOEC (Growth Rate) 72 h ≤ 0.09 mg/L --
LOEC (Yield) 72 h ≤ 0.09 mg/L --
72h ErC10 0.57 mg/L 0.33 – 0.98 mg/L
72h EyC10 n. d. --
72h ErC50 2.35 mg/L 1.25 – 4.35 mg/L
72h EyC50 0.23 mg/L 0.21 – 0.24 mg/L

Results with reference substance (positive control):

The 72h-EC50 values of potassium dichromate were determined in a separate reference test. For the estimation of the 72h-EC50 values of the positive control, the fits showed sufficient statistical correspondence of the data with the dose-response-equation. The values were within the range of the laboratory.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Significant inhibition of algal growth was observed at all tested concentrations.

Executive summary:

The study was performed using 5 concentrations ranging from 0.1 to 10 mg/L. Incubation time (test system Desmodesmus subspicatus) was 72 hours. The cell concentration of each replicate was determined by measuring the cell numbers every 24 hours with an electronic particle counter. Growth rate µ and the yield were determined from the cell number at the respective observation times.

Significant inhibition of algal growth was observed at all tested concentrations.

Due to the high inhibition values in the lowest concentration for the endpoint yield no EC₁₀ could be determined and for both endpoints the LOEC and NOEC therefore was given as a range.