Sodium selenate

Toxicity to birds

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to birds

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No guideline used. Se concentrations in the food were not verified. Test conditions documentation is acceptable.

Qualifier:

no guideline followed

Principles of method if other than guideline:

One-day-old male broiler chicks were provided a diet that contained either no or one of 4 Se concentrations added as sodium selenite. This diet was fed to the chicks for 21 days, at which point any effects on growth were determined.

GLP compliance:

not specified

Dose method:

feed

Analytical monitoring:

yes

Vehicle:

no

Details on preparation and analysis of diet:

DIET PREPARATION
- Description and nutrient analysis of basal diet provided in study report: yes

HOMOGENEITY AND STABILITY OF TEST MATERIAL IN DIET
- Se content in diet was determined by the method of Wetter and Ulrey (1978). No further information was given on sampling time, frequency of Se analysis, method of analysis, etc.
- Measured Se concentrations were not reported.

Test organisms (species):

other: Gallus domesticus

Details on test organisms:

TEST ORGANISM
- Common name: chicken
- Source: no data
- Age at test initiation (mean and range, SD): one day old broiler chicks
- Sexes used: male
- Housing: in electrically heated battery brooders with wire floors

Limit test:

no

Total exposure duration (if not single dose):

21 d

No. of animals per sex per dose and/or stage:

4x10 per treatment

Control animals:

yes, concurrent no treatment

Nominal and measured doses / concentrations:

Nominal: 0, 0.1, 0.25, 1 and 5 mg Se/kg diet

Details on test conditions:

PEN SIZE AND CONSTRUCTION MATERIALS
- Description: electrically heated battery brooders with wire floors

NO. OF BIRDS PER REPLICATE
- For negative control: 10
- For treated: 10

NO. OF REPLICATES PER GROUP
- For negative control: 4
- For treated: 4

TEST CONDITIONS (range, mean, SD as applicable)
- no data

Details on examinations and observations:

BODY WEIGHT
- Time schedule for examinations: At 3 weeks of age, the chicks were weighed by pen.

OTHER:
- Feed consumption was determined in order to calculate feed-gain ratios.
- Three chicks from each pen were killed at the end of testing to obtain livers for Se analysis.

Details on reproductive parameters:

not applicable

Duration (if not single dose):

21 d

Dose descriptor:

NOEC

Effect level:

1 mg/kg diet

Conc. / dose based on:

element

Remarks:

Se

Basis for effect:

other: growth

Remarks on result:

other: (< 5% effect)

Mortality and sub-lethal effects:

BODY WEIGHT
- Results: Adding an excess of Se to the corn-soy diet adequate in Se resulted in reduced growth rate and feed efficiency and increased Se deposition of the liver.

Effects on reproduction:

not applicable

Further details on results:

In the highest dose group, a large increase in the amount of liver Se was noticed (see Table 1).

Reported statistics and error estimates:

Type IV sum of squares to determine significance.

Table 1. Effects of Selenium on chick growth over a 21-day feeding period.
Added Se (mg/kg)	Body weight (3 wks)	Feed/gain	Liver Se (µg/g)
0	528	1.52	0.21
0.1	542	1.45	0.47
0.25	545	1.45	0.53
1	503	1.49	0.82
5	405	1.74	3.54

 

Conclusions:

Klimisch 2 study in which one-day-old male chicks were fed for 21 days with either a diet without Se or a diet with one of four Se concentrations (added as selenite). Body weight, food consumption, and liver Se were determined during the study. The 21-day NOEC for growth was determined to be 1 mg Se/kg diet.

Description of key information

The most critical NOEC is a 21-day NOEC of 1 mg Se/kg diet for effect of Se on growth of Gallus domesticus fed ad libitum with a selenium contaminated diet in electrically heated battery brooders (Jensen, 1986; Klimisch 2).

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for birds:

1 mg/kg food

Additional information

Several studies are available for the long-term toxicity of various Se compounds (selenium, Na₂SeO₃, H₂SeO₃, Na₂SeO₄, seleno-methionine, seleno-cysteine, SeO₂) to mortality, body weight or reproduction of 6 bird species: chicken (Gallus domesticus), duck (Anas platyrhynchos), Japansese quail (Coturnix coturnix japonica), American kestrel (Falco sparverius), black-crowned night-heron (Nycticorax nycticorax) and owl (Otus asio) (US EPA, Ecological Soil Screening Levels for Selenium, 2007). These studies cover several endpoints such as egg weight, hatchability, egg production and survival of ducklings for exposure periods between 1 and 105 weeks and the NOEC values vary between 1 and 40 mg Se/kg diet. No consistent and significant difference in toxicity was observed among the various Se compounds tested and therefore, all data were grouped for the assessment of Se compounds. Studies reporting the lowest NOEC values were screened for their reliability and the lowest reliable NOEC value among all data is a 21-day NOEC of 1 mg Se/kg diet for effect of Se on growth of Gallus domesticus which were fed a selenium contaminated diet (Jensen, 1986). This study is selected for the effects assessment of dietary toxicity of Se.