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Ecotoxicological information

Toxicity to soil macroorganisms except arthropods

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Endpoint:
toxicity to soil macroorganisms except arthropods: long-term
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
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):
Eisenia fetida
Animal group:
annelids
Details on test organisms:
no data
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Remarks:
exact test duration not reported
Test temperature:
no data
pH:
7.1
Moisture:
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.:
1.7 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Remarks:
Se
Basis for effect:
reproduction
Remarks on result:
other: NOEC calculated as EC20/2; test duration not reported
Dose descriptor:
other: EC20
Effect conc.:
3.4 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 Eisenia fetida. 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 3.4 mg Se/kg dw. An approximate NOEC was obtained dividing the EC20 by a factor of 2, resulting in a NOEC value of 1.7 mg Se/kg dw.
Endpoint:
toxicity to soil macroorganisms except arthropods: long-term
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
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):
other: Enchytraeus crypticus
Animal group:
annelids
Details on test organisms:
no data
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Remarks:
exact test duration not reported
Test temperature:
no data
pH:
7.1
Moisture:
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.:
2.2 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.:
4.4 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 Enchytraeus crypticus. 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 4.4 mg Se/kg dw. An approximate NOEC was obtained dividing the EC20 by a factor of 2, resulting in a NOEC value of 2.2 mg Se/kg dw.
Endpoint:
toxicity to soil macroorganisms except arthropods: long-term
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 220 (Enchytraeid Reproduction Test)
Version / remarks:
2004
Deviations:
yes
Remarks:
The optimum temperature for growth and reproduction of E. albidus is between 15 and 21°C. That is why the tests were performed at 18 +- 0.8 °CC instead of 20 +- 0.8 0CC as the guideline No. 220 suggests.
GLP compliance:
not specified
Specific details on test material used for the study:
Na2O4Se, SigmaeAldrich, No. 71948
Analytical monitoring:
yes
Details on sampling:
Soils were sampled from each concentration 24-48 hours after spiking and stored at 4°C for up to one week until Se analyses.
Vehicle:
no
Test organisms (species):
Enchytraeus albidus
Animal group:
annelids
Details on test organisms:
TEST ORGANISM
- Common name: Pot worm
- Source: originated from the E. albidus stock cultures of the Department of Zoology and Ecology, Szent István University
- Age at test initiation (mean and range, SD): adult worms with fully developed clitellum and visible eggs
- The culture is kept according to Römbke and Moser 2002
Study type:
laboratory study
Substrate type:
natural soil
Limit test:
no
Total exposure duration:
6 wk
Test temperature:
18 +- 0.8 °C
Moisture:
The soils were watered to 55e60% of their water holding capacity with Na-selenate or Na-selenite solutions.
Details on test conditions:
TEST SYSTEM
- Test container (material, size): 150 mL covered glass containers
- Amount of soil or substrate: 20 g oven dry Ko or KA soil
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 5
- No. of replicates per control: 10

SOURCE AND PROPERTIES OF SUBSTRATE (if soil)
- Geographic location: A chernozem brown forest soil was collected from the top 20 cm of control plots at the experimental fields of the Agricultural Research Institute “Fleischmann Rudolf” of the Károly Róbert University (designated as Kompolt soil, KO) and a meadow chernozem from the top 20 cm of the control plots at the Research Institute of Karcag (Debrecen University), designated as Karcag soil (KA).
-- % sand: KO: 5%; KA: 0%
- % silt: KO: 49%; KA: 53%
- % clay: KO: 46%; KA: 47%
- Organic carbon (%): KO: 2.7%; KA: 2.9%
- CaCo3: KO: 0%; KA: 2%

OTHER TEST CONDITIONS
- Photoperiod: the tests were performed in total darkness

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): mortality and reproduction
Nominal and measured concentrations:
KO soil
selenate
nominal 0.94, 1.88, 3.79, 7.5, 15, 30 mg/kg
measured total 2.92, 6.14, 12.5, 25.6, 49.5, 101.5 mg/kg
measured available 2.79, 6.04, 11.8, 25.1, 48.4, 98.5 mg/kg
selenite
nominal 4.7, 9.38, 18.75, 37.5, 75, 150 mg/kg
measured total 3.88, 8.89, 16.8, 33.2, 70.7, 144.5 mg/kg
measured available 0.27, 0.61, 1.42, 3.37, 10.2, 31.7 mg/kg

KA soil
selenate
nominal 3.38, 6.75, 12.5, 25, 50, 100 mg/kg
measured total 1.66, 3.42, 5.77, 12.9, 24.8, 31.9 mg/kg
measured available 1.55, 2.56, 5.33, 12.4, 24.5, 31.5 mg/kg
selenite
nominal 6.25, 12.5, 25, 50, 100, 150 mg/kg
measured total 8.39, 17.1, 31.3, 62.9, 107.7, 136.1
measured available 2.50, 5.94, 13.1, 32.2, 59.3, 80.2 mg/kg

Key result
Duration:
6 wk
Dose descriptor:
NOEC
Effect conc.:
3.4 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KA soil
Key result
Duration:
6 wk
Dose descriptor:
NOEC
Effect conc.:
3.4 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KA soil
Duration:
6 wk
Dose descriptor:
LOEC
Effect conc.:
5.8 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KA soil
Duration:
6 wk
Dose descriptor:
LOEC
Effect conc.:
5.8 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KA soil
Duration:
6 wk
Dose descriptor:
LOEC
Effect conc.:
<= 2.9 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KO soil
Duration:
6 wk
Dose descriptor:
LOEC
Effect conc.:
<= 2.9 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KO soil
Duration:
6 wk
Dose descriptor:
LC50
Effect conc.:
6.9 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KO soil, R² = 0.97
Duration:
6 wk
Dose descriptor:
LC50
Effect conc.:
6.7 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Remarks:
Se, available fraction
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KO soil, R² = 0.98
Duration:
6 wk
Dose descriptor:
LC50
Effect conc.:
6.8 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KA soil, R² = 0.96
Duration:
6 wk
Dose descriptor:
LC50
Effect conc.:
6.2 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Remarks:
Se, available fraction
Basis for effect:
mortality
Remarks on result:
other:
Remarks:
KA soil, R² = 0.99
Duration:
6 wk
Dose descriptor:
EC50
Effect conc.:
1.8 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KO soil, R² = 0.95
Duration:
6 wk
Dose descriptor:
EC50
Effect conc.:
1.7 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Remarks:
Se, available fraction
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KO soil, R² = 0.96
Duration:
6 wk
Dose descriptor:
EC50
Effect conc.:
5 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element (total fraction)
Remarks:
Se
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KA soil, R² = 0.99
Duration:
6 wk
Dose descriptor:
EC50
Effect conc.:
4.6 mg/kg soil dw
Nominal / measured:
meas. (not specified)
Conc. based on:
element
Remarks:
Se, available fraction
Basis for effect:
reproduction
Remarks on result:
other:
Remarks:
KA soil, R² = 0.99
Conclusions:
This Klimisch 1 study was performed according to OECD guideline 220. It was a well performed and well documented study that evaluated the effects of sodium selenite and sodium selenate on reproduction and mortality of adult pot worms (Enchytraeus albidus) for two soils (KO and KA soil). For sodium selenite; the 6-week NOEC for reproduction was 3.9 mg Se/kg dw and 8.4 mg Se/kg dw for KO and KA soil, respectively and the 6 week NOEC for mortality was 8.9 mg Se/kg dw and 8.4 mg Se/kg dw for KO and KA soil, respectively. For sodium selenate; the 6-week LOEC for reproduction was 2.9 mg Se/kg dw and 5.8 mg Se/kg dw for KO and KA soil, respectively and the 6 week LOEC for mortality was 2.9 mg Se/kg dw and 5.8 mg Se/kg dw for KO and KA soil, respectively.

Description of key information

In total, 3 reliable NOEC values for chronic selenate toxicity to terrestrial invertebrates except arthropods were retrieved from 2 published studies (Checkai et al., 2004 and Somogyi et al., 2012). All data were derived from soils amended with disodium selenate. The data cover selenate toxicity to reproduction of 3 different species (Eisenia fetida, Enchytraeus albidus and Enchytraeus crypticus). NOEC values vary between 1.7 mg Se/kg dw for Eisenia fetida and 3.4 mg Se/kg dw for Enchytraeus albidus. All NOEC values are expressed based on added elemental Se concentrations in soil. All reliable NOEC values were taken forward to the derivation of the PNEC according to the statistical extrapolation approach.

Key value for chemical safety assessment

Additional information

Reliable results are available for the toxicity of Na2SeO3 and Na2SeO4 to soil macro-organisms except arthropods. Somogyi et al. (2007 and 2012) studied the effect of both Na2SeO3 and Na2SeO4 on mortality and reproduction of the potworm Enchytraeus albidus according to the OECD 220 guideline. There was a significant difference in toxicity between selenite and selenate, with selenate showing significantly higher toxicity. This is consistent with data for plants and the lower adsorption of selenate in soil compared to selenite. Therefore, only the available reliable results for selenate are taken into account for the hazard assessment of hexavalent inorganic selenium substances.

Reliable chronic NOEC values for toxicity of sodium selenate are available for 3 organisms: Eisenia fetida, Enchytraeus crypticus and Enchytraeus albidus and vary between 1.7 and 3.4 mg Se/kg soil. The lowest reported reliable NOEC for Na2SeO4 was 1.7 mg Se/kg soil (calculated as EC20/2) for reproduction of Eisenia fetida after 13 weeks exposure (Checkai et al., 2004).

All results are based on nominal added or background corrected measured Se concentrations.