Loperamide

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 August 11 to August 14, 2015

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Report date:

2015

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Loperamide

EC Number:

258-416-5

EC Name:

Loperamide

Cas Number:

53179-11-6

Molecular formula:

C29H33ClN2O2

IUPAC Name:

4-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]-N,N-dimethyl-2,2-diphenylbutanamide

Details on test material:

Name Loperamide base (CAS 53179-11-6)
Batch no. 02742200215
Appearance White solid
Purity 99.5 %
Homogeneity Homogeneous
Expiry date 20. Aug. 2015

Test solutions

Details on test solutions:

For the treatment, 350 mL of the test item solution was mixed with the necessary amount of algal pre-culture (0.83 mL) to achieve a cell concentration of approximately 6.5 *103 cells/mL. In this mixture, the pH-value was measured. Samples for the analytical determination were taken.
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 (0.83 mL). The test vessels were filled with 45 ml of the respective test solution and incubated for 72 hours, shaken on an orbital shaker. Before the start of incubation and every 24 hours, the cell number was calculated based on the determination of the light absorption at 440 nm. After the test, the pH value in treatments and 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 concentration of the test item in the test vessels was measured at the start and at the end of the test.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

SAG Strain Number 86.81
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

Water media type:

freshwater

Total exposure duration:

72 h

Test conditions

Test temperature:

21.5 – 26.8 °C

pH:

7.6 - 7.8

Nominal and measured concentrations:

At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC. The measured concentrations were 91 % the nominal concentration at the start and 70 % of the nominal concentration at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

Details on test conditions:

Number of replicates: six replicates for the control,; six replicates for the solvent control and six replicates for the treatment
Lighting: 5300 Lux
Blank control: deionised water with nutrient medium and algae

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.48 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

>= 0.48 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Effect concentrations 3

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

> 0.48 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Details on results:

The study was performed using one concentration at the limit of solubility containing 0.6 mg/L.

Any other information on results incl. tables

No significant inhibition of algal growth was observed.

At the start and at the end of the test, the content of the test item in the test solutions was determined using HPLC. The measured concentration was 91 % the nominal concentration at the start of the test.

Thus the measured concentration was 70 % of the nominal concentration at the end of the test. Therefore the geometric mean of the measured concentration was used for the determination of the results. The 72h-EC50s of potassium dichromate were determined in a separate reference test. For the estimation of the 72h-EC50s of the positive control, the fits showed sufficient statistical correspondence of the data with the dose-response-equation. The values were within the normal range of the laboratory.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

No significant inhibition of algal growth was observed at the limit of solubility of 0.6 mg/l.
The measured concentrations were 91 % the nominal concentration at the start and 70 % of the nominal concentration at the end of the test. Therefore, the determination of the results was based on the geometric mean of the measured concentrations.

EC50 > 0.48 mg/l (growth rate and Yield)