Gadoliniumsulfite trihydrate

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

not specified

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Gadoliniumsulfite trihydrate

EC Number:

456-900-2

EC Name:

Gadoliniumsulfite trihydrate

Cas Number:

51285-81-5

Molecular formula:

Gd2(SO3)3*3H2O

IUPAC Name:

digadolinium(3+) trihydrate trisulfite

Test material form:

solid: particulate/powder

Details on test material:

Off white, crystalline powder
Batch number FSG 3896 or 02-FW-095

Sampling and analysis

Analytical monitoring:

yes

Remarks:

ICP-OES with extemal calibration

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

The test system used for this study was a green unicellular algae species, Desmodesmus subspicatus, strain No. SAG 86. 81, supplied by the "Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universität Göttingen". This strain is recommended by international guidelines.

Study design

Test type:

static

Limit test:

yes

Total exposure duration:

72 h

Test conditions

Test temperature:

22 to 23°C

pH:

Start of the experiement: ca. 8
End of the experiment: ca. 11

Nominal and measured concentrations:

At the start, the analytically determined concentrations were about 2.38-3.13 % of the nominal concentrations. At the end of the experimental part, the analytically determined test material concentrations were 2.43 - 3.34 % of the nominal concentrations. Nominal: 5, 11, 22, 47, 100 mg/L and Measured: 0.16, 0.31, 0.66, 1.59, 2.70 mg/L

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.31 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

other: EbC50

Effect conc.:

2.08 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Key result

Duration:

72 h

Dose descriptor:

other: ErC50

Effect conc.:

2.58 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

The median effective concentration (EC50), which would result in a 50 % growth inhibition and the 95% confidence interval compared to the control, was calculated from the analytically determined concentrations of Gadoliniumsulfite trihydrate. Furthermore the no observed effect concentration (NOEC) is given below.
72 h EbC50       :        2.08 (1.91 - 2.25) mg/L
72 h ErC50       :        2.58 (2.41- 2.77) mg/L
NOEC              :         0.31 mg/L

Executive summary:

The influence of Gadoliniumsulfite trihydrate on the growth and growth rate ofthe green algae species Desmodesmus subspicatus was tested. Aliquots of the test material were filled in 100 ml Erlenmeyer flasks with 120 ml test medium and sealed to form a closed system reducing the loss of test material concentrations within the exposure period. The algae were exposed to different concentrations of test material and the growth was calculated after 24, 48, or 72 hours of exposure in the test media. Based on the results of a previous study, the study with Gadoliniumsulfite trihydrate was performed with nominal concentrations of 5, 11, 22, 4 7, and 100 mg/L reconstituted water. The study design included three replicates per test material concentration, each containing about 120 ml test medium and 10,000 cells/ml at the start of the experimental phase and a control without algae. Analyses of the test material concentrations were performed with all doses at the start and after 24, 48, or 72 hours. The Iimit of quantification of the analytical method was about 0.015 mg/L. At the start, the analytically determined concentrations were about 2.38-3.13 % of the nominal concentrations. At the end of the experimental part, the analytically determined test material concentrations were 2.43 - 3.34 % of the nominal concentrations. During the experimental phase of the study, the test material concentrations could not be maintained at >= 80 % of the initial concentrations. Therefore, the EC50 values were calculated with the analytically determined concentrations. The concentrations were calculated with the "formula for calculating geometric mean exposure concentration". The median effective concentration (EC50), which would result in a 50 % growth inhibition and the 95% confidence interval compared to the control, was calculated from the analytically determined concentrations of Gadoliniumsulfite trihydrate. Furthermore the no observed effect concentration (NOEC) is given below.

72 h EbC50       :        2.08 (1.91 - 2.25) mg/L

72 h ErC50       :        2.58 (2.41- 2.77) mg/L

NOEC              :         0.31 mg/L