Sodium selenate

Toxicity to terrestrial arthropods

Link to relevant study record(s)

Reference

Endpoint:

toxicity to non-target arthropods on natural substrate (NTA other than pollinators)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Only short summary available, it seems that tests were performed according to scientific standards

Qualifier:

no guideline followed

Principles of method if other than guideline:

Not reported which guideline was followed. Selenium was added as sodium selenate, and weathered/aged in soil via alternating wetting/drying cycles for 13 weeks. Soil organisms were then exposed for a non-reported test duration for establishment of EC20 ecotoxicological benchmarks based on reproduction.

GLP compliance:

not specified

Application method:

soil

Analytical monitoring:

yes

Details on sampling:

Soil samples from each treatment were taken for Se analysis at test initiation and finalization.

Vehicle:

no

Details on preparation and application of test substrate:

Selenium was added as sodium selenate and weathered/aged in soil via alternating wetting/drying cycles for 13 weeks.

Test organisms (species):

Folsomia candida

Animal group:

Collembola (soil-dwelling springtail)

Details on test organisms:

no data

Study type:

laboratory study

Limit test:

no

Remarks:

exact test duration not reported

Test temperature:

no data

pH (if soil or dung study):

7.1

Humidity:

no data

Photoperiod and lighting:

no data

Details on test conditions:

TEST SYSTEM
- Test container (material, size): no data
- Amount of soil or substrate: no data
- No. of organisms per container (treatment): no data
- No. of replicates per treatment group: no data
- No. of replicates per control: no data
- No. of replicates per vehicle control: no data

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Sassafras sandy loam (fine-loamy siliceous, mesic Typic Hapludult)
- % sand: 70%
- % silt: 13%
- % clay: 17%
- Organic carbon (%): 1% organic matter
- Maximum water holding capacity (in % dry weigth): no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): reproduction

Nominal and measured concentrations:

no data

Key result

Dose descriptor:

NOEC

Effect conc.:

2.35 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

reproduction

Remarks on result:

other: calculated as EC20/2; test duration not reported

Dose descriptor:

other: EC20

Effect conc.:

4.7 mg/kg soil dw

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Se

Basis for effect:

reproduction

Remarks on result:

other: test duration not reported

Reported statistics and error estimates:

EC20 estimated by nonlinear regression

Conclusions:

This Klimisch 2 study reports the results of an experiment that evaluated the effects of sodium selenate on the reproduction of Folsomia candida. The organisms were exposed to spiked soil after 13 weeks of equilibration via alternating wetting/drying cycles. The exposure duration was not reported. The EC20 for reproduction was reported to be 4.7 mg Se/kg dw. An approximate NOEC was obtained dividing the EC20 by a factor of 2, resulting in a NOEC value of 2.35 mg Se/kg dw.

Description of key information

One reliable NOEC value for chronic selenate toxicity to reproduction of Folsomia candida was retrieved (Checkai et al., 2004; test substance disodium selenate). A NOEC of 2.23 mg Se/kg dw was derived by dividing the reported EC₂₀ of 4.7 mg Se/kg dw by a factor 2. The NOEC was expressed based on added elemental Se concentration in soil and was taken forward to the derivation of the PNEC according to the statistical extrapolation approach

Additional information

Only one reliable (Klimisch 2) result is available for the effect of Na₂SeO₄ to reproduction of the terrestrial arthropod Folsomia candida, reporting a NOEC of 2.35 mg Se/kg soil (calculated as EC₂₀/2, based on added Se concentration; Checkai et al., 2004). No results were available for the effect of selenite on terrestrial arthropods.

Supporting information is available on the toxicity of various Se compounds to bees (Apis mellifera). The effects of organic ((methyl-)selenocysteine) and inorganic (selenite and selenate) selenium compounds in the diet (sucrose) on larval and forager stages were studied. EC₅₀ values ranged from 0.72 to 161 mg Se/L. Organic selenium compounds were less toxic (> factor 3) then inorganic compounds, but differences selenite and selenate were limited. The most sensitive endpoint was found for the larval survival of Apis mellifera exposed to selenate (EC₅₀ = 0.72 mg Se/L).