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Toxicity to birds

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Endpoint:
long-term toxicity to birds
Data waiving:
other justification
Justification for data waiving:
other:
Endpoint:
toxicity to birds, other
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: see 'Remarks'
Remarks:
Non-guideline study with significant methodological deficiencies. No information provided on the test material, on test conditions (temperature, lighting), on the source of the test animals and the preparation of the diet with the test substance. No analysis of the test substance in the diet. Only one test concentration was tested.
Justification for type of information:
see attachment β€œRead-across concept – Human Health/Environment - Category approach for Inorganic sulfites/thiosulfates/dithionite" in section 13.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Sodium metabisulfite (SMBS) and phytase, individually and in combination, were included in steam-pelleted, sorghum-based broiler (Gallus gallus domesticus) diets from 7 to 28 days post-hatch.
GLP compliance:
not specified
Dose method:
feed
Analytical monitoring:
no
Vehicle:
not specified
Details on preparation and analysis of diet:
DIET PREPARATION
- Description and nutrient analysis of basal diet provided in study report: yes
- Preparation of doses: Sorghum FW14 was incorporated into a basal grower diet at 580 g/kg formulated to contain 201.2 g/kg of protein with an energy density of 12.94 MJ/kg. The basal diet was formulated to be P-adequate with a non-phytate-P content
of 4.5 g/kg. SMBS and a Buttiauxella phytase (Axtra PHY,Danisco Animal Nutrition, Marlborough, Wiltshire, UK) were included in the basal diet at 1.75 g/kg and 1000 FTU/kg, respectively.
Test organisms (species):
other: Gallus gallus domesticus
Details on test organisms:
TEST ORGANISM
- Common name: broiler chicken
- Source: Ross 308
- Age at test initiation (mean and range, SD): 7 dph (days post-hatch)
- Sexes used / mixed or single sex: male
Limit test:
no
Total exposure duration (if not single dose):
21 d
Remarks:
fomr 7 dph to 28 dph
No. of animals per sex per dose and/or stage:
42 animals per treatment: 7 replicate cages with 6 birds per cage (male only).
Control animals:
yes, plain diet
Nominal and measured doses / concentrations:
Nominal: 0 (control), 1.75 g SMBS/kg
Details on test conditions:
PEN SIZE AND CONSTRUCTION MATERIALS
- Description: cage
- Caging: group

NO. OF BIRDS PER STAGE OR REPLICATE
- For negative control: 6
- For treated: 6

NO. OF STAGES OR REPLICATES PER GROUP
- For negative control: 7
- For treated: 7

TEST CONDITIONS (range, mean, SD as applicable)
- not specified
Details on examinations and observations:
MORTALITY / CLINICAL SIGNS
- Time schedule for examinations: daily
- Remarks: the incidence of dead or culled birds was recorded

BODY WEIGHT
- Time schedule for examinations: not specified

FOOD CONSUMPTION
- Time schedule for examinations: not specified

ORGAN WEIGHTS
- Dose groups that were examined: negative control, 1.75 g/kg
- Organs: gizzard, pancreas
Details on reproductive parameters:
Not determined.
Reference substance (positive control):
no
Mortality and sub-lethal effects:
Mortality/cull rate (%) in the 1.75 g SMBS/kg treatment was 5.56 % and not significantly different from the negative control (4.76 %).
Further details on results:
No significant differences of the SMBS treatment compared to the negative control were observed for the test parameters weight gain, feed intake, feed conversion rate and relative organ weights.
Reported statistics and error estimates:
Experimental data was analysed as a 2 by 2 factorial arrangement of dietary treatments using the IBM SPSS Statistics 20 program (IBM Corporation, Somers, NY, USA). The experimental units were cage means and statistical procedures included univariate ANOVA using the general linear models procedure, linear regressions and Pearson correlations. When appropriate, the significance of pair-wise comparisons was taken into consideration. A probability level of less than 5% was considered to be statistically significant.

Table: Effects of sodium metabisulfite (SMBS) on growth performance from 7 to 28 days post-hatch, relative organ weights and gizzard pH of broiler chickens

Treatment

Growth performance

 

Relative organ weights and pH

SMBS (g/kg)

Phytase (FTU/kg)

Weight gain (g/bird)

Feed intake (g/g)

Feed conversion ratio (g/g)

Mortality/cull rate (%)

Gizzard weight (g/kg)

Pancreas weight (g/kg)

Gizzard pH

0

0

1552

2416

1.566

4.76

21.40

2.86

2.85

1.75

0

1582

2398

1.517

5.56

16.22

2.15

3.09

Validity criteria fulfilled:
not applicable
Conclusions:
No effects of sodium metabilsulfite added to a sorghum-based diet at 1.75 g/kg were observed in broiler chickens exposed from 7 to 28 days post-hatch in regard to mortality/cull rate as well as weight gain, feed intake and feed conversion.

Description of key information

Key value for chemical safety assessment

Additional information

In a supporting study by Truong et al. (2016), effects of disodium disulfite added to a sorghum-based diet at 1.75 g/kg were not observed in broiler chickens exposed from 7 to 28 days post-hatch, including mortality/cull rate as well as weight gain, feed intake and feed conversion. Due to methodological deficiencies the study cannot be considered reliable. However, results indicate a low potential for the toxicity of sulfite/disulfite substances to birds exposed via the diet.