Selenious acid

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1992-08-18 to 1992-08-21

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study. Well performed. Not entirely clear whether effect concentrations were expressed as concentrations of sodium selenite or selenium. Assumed sodium selenite and recalculated to selenium.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Sodium selenite

EC Number:

233-267-9

EC Name:

Sodium selenite

Cas Number:

10102-18-8

Molecular formula:

H2O3Se.2Na

IUPAC Name:

disodium selenite

Details on test material:

- Name of test material (as cited in study report): Sodium selenite
- Molecular formula (if other than submission substance): Na2SeO3
- Molecular weight (if other than submission substance): 173 g/mol
- Physical state: white powder
- Analytical purity: > 99.5
- Solubility: Good

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Frequency: No data

Test solutions

Vehicle:

no

Details on test solutions:

see test conditions

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Selenastrum capricornutum
- Source: LISEC laboratory culture (ex. CCAP 278/4)
- Age of inoculum (at test initiation): 4 days (exponential growth phase reached after 4 days of preculturing)

ACCLIMATION
- Acclimation period: 4 days of preculturing
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: no

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

No data (hardness of algal medium recommended by OECD guideline 201)

Test temperature:

23.4-24.8 °C

pH:

8.26-9.18

Dissolved oxygen:

No data

Salinity:

Not applicable

Nominal and measured concentrations:

0 (control), 10, 18, 32, 58 and 100 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: 150 mL borosilicate glass Erlenmeyers covered with cotton wool and containing 100 mL of test medium
- Initial cells density: 10000 cells/mL
- Control end cells density: Increased by a factor of 100 within 3 days
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- In order to keep the algae in suspension and to facilitate transfer of CO2, the Erlenmeyers were continuously shaken on a laboratory shaker (Gerhardt Type LS20)

GROWTH MEDIUM
- Standard medium used: yes (according to OECD 201)

OTHER TEST CONDITIONS
- Light intensity and quality: 10000 lux (Philips TL-33 lamps)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: The cell concentration was determined by absorbance at 0, 24, 48 and 72 hours using a Varian Superscan UV/VIS Spectrophotometer (wavelength: 720 nm, special band width: 4 nm, cuvettes with light paths of 5 cm).
- Other: At the end of the test deformations of algal cells were evaluated using a microscope at 200x magnification

TEST CONCENTRATIONS
- Range finding study: 1, 3.2, 10, 32 and 100 mg/L
- Test concentrations: 0, 10, 18, 32, 58 and 100 mg/L

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

4 570 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

growth rate

Remarks:

and biomass

Effect concentrations 2

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

8 220 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

growth rate

Remarks:

and biomass

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

44 240 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

growth rate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

15 570 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

biomass

Details on results:

biomass-based effect concentrations (area under the growth curve)
- 72-h NOEC = 4570 µg/L
- 72-h LOEC = 8220 µg/L
- 72-h EC50 = 15570 µg/L

Reported statistics and error estimates:

EC50 values calculated using the logit model of Chou and Chou (1985). It is not reported which statistic test is used to determine NOEC and LOEC values.

Any other information on results incl. tables

Not entirely clear whether effect concentrations were expressed as concentrations of sodium selenite or selenium. Assumed sodium selenite and recalculated to selenium.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Reliable (Klimisch 2) study on the toxicity of sodium selenite to Selenastrum capricornutum. The 72-h NOEC, LOEC and EC50 were determined using both growth rate and biomass (area under the growth curve) as endpoints. The growth rate-based NOEC, LOEC and EC50 values were 4570, 8220 and 44240 µg Se/L, respectively. Considering biomass as an endpoint the NOEC, LOEC and EC50 were 4570, 8220 and 15750 µg Se/L, respectively.