Sodium selenite

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well performed study. Conducted according to US EPA guidelines for acute testing. LC50 values based on measured Se concentrations.

Qualifier:

according to guideline

Guideline:

other: EPA-660/3-75-009: Methods for Acute Toxicity Tests with Fish, Macroinvertebrates, and Amphibians

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

- Frequency: At the start and end of exposure

Vehicle:

no

Details on test solutions:

see test conditions

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: Laboratory stock
- Age at study initiation: Neonates
- Feeding during test: No

ACCLIMATION
- Acclimation period: no data

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

as measured ± 3% mg/L as CaCO3

Test temperature:

20 ± 0.1 °C

pH:

8.2 ± 0.1

Dissolved oxygen:

8.6 ± 0.2 mg/L

Salinity:

Not applicable

Nominal and measured concentrations:

as calculated ± 5% mg Se/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 500 ml acid-washed glass jars with 100 mL of test medium
- Renewal rate of test solution (frequency/flow rate): 95% of solution replaced at 24 hours
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted, moderately hard, fresh water that contained salt concentrations twice those in EPA soft fresh water. The initial water was reverse-osmosis-treated water that met EPA specifications, to which 96 mg/L NaHCO3, 60 mg/L CaSO4.2H2O, 60 mg/L MgSO4, and 4 mg/L KCl (all reagent grade) were added.
- Sulfate: 81.5 mg/L

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

550 µg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

mortality

Reported statistics and error estimates:

LC50 values were interpolated by probit analysis, using the SAS statistical program.

Conclusions:

Reliable (Klimisch 1) study on toxicity of sodium selenite to Daphnia magna. The 48-h LC50 value was 550 µg Se/L.

Description of key information

The most critical EC50 was a 48-h EC50 value for Daphnia magna from an acute toxicity test with sodium selenite. No reliable data were identified for marine invertebrates.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

550 µg/L

Additional information

Reliable data are available for H₂SeO₃, Na₂SeO₃, Na₂SeO₄ and selenomethionine (both seleno-L- and seleno-DL-methionine). All reliable data are for freshwater organisms: 6 Crustacea (Daphnia magna, Daphnia pulex, Ceriodaphnia dubia, Hyalella azteca, Gammarus pseudolimnaeus, and Gammarus lacustris), and 2 insects (Diptera: Chironomus riparius and Chironomus decorus). No reliable data are available for brackish or marine organisms. All results are based on added dissolved Se concentrations.

The data for Se-(D)L-methionine are not taken into account for the assessment of direct effects of inorganic selenium compounds to aquatic organisms because there is some concern on different biochemical behaviour of this selenium containing amino acid compared to inorganic Se compounds. The short-term L(E)C50 values for inorganic Se substances vary between 550 and 48200 µg Se/L. The highest value represents a 48-h LC50 for larvae of the dipteran species Chironomus decorus obtained in a test with sodium selenite (Maier and Knight, 1993). The lowest value is a 48-h EC50 value for Daphnia magna reported by Maier et al. (1993) for the same substance. L(E)C50 values for disodium selenate range from 580 to 23700 µg Se/L. Selenium toxicity appears to differ strongly among the invertebrate species. No consistent differences in toxicity are found across Se substances for all aquatic invertebrate species tested (L(E)C50 values for Se-(D)L-methionine vary between 310 and 194000 µg Se/L).

For Chironomus decorus, a short-term dietary toxicity study was also considered reliable (although usually not considered under REACH). The dietary toxicity study observed significant growth reduction at 2.84 mg Se/kg dw in food for Na₂SeO₃ and at 2.11 mg Se/kg dw in food for Na₂SeO₄ (corresponding with 4.05 and 2.55 mg Se/kg dw whole body, respectively).