Myo-inositol

Long-term toxicity to fish

Administrative data

Endpoint:

fish, juvenile growth test

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference

Reference Type:

publication

Title:

Juvenile Tilapia (Oreochromis niloticus x Oreochromis aureus) Requires Ddietary Myo-inositol for Maximal Growth

Author:

Shiau S-Y and Su S-L

Year:

2005

Bibliographic source:

Aquaculture, 243:273– 277

Materials and methods

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

An 8-week growth experiment was conducted to estimate the dietary requirement of the test substance for juvenile hybrid tilapia.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Myo-inositol

EC Number:

201-781-2

EC Name:

Myo-inositol

Cas Number:

87-89-8

Molecular formula:

C6H12O6

IUPAC Name:

cyclohexane-1,2,3,4,5,6-hexol

Test material form:

solid

Details on test material:

- Purity: not reported

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

other: Oreochromis niloticus x Oreochromis aureus

Study design

Test type:

other: Feeding study

Water media type:

freshwater

Limit test:

no

Total exposure duration:

8 wk

Post exposure observation period:

None

Test conditions

Hardness:

not reported

Test temperature:

26±1°C

pH:

not reported

Dissolved oxygen:

not reported

Conductivity:

not reported

Nominal and measured concentrations:

150, 250, 350, 450, 600, and 1200 mg/kg diet in the basal diet providing 167, 259, 367, 479, 612, and 1253 mg/kg diet, respectively.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Key result

Duration:

8 wk

Dose descriptor:

LC50

Effect conc.:

>= 1 200 other: mg/kg in diet

Nominal / measured:

nominal

Basis for effect:

mortality

Remarks on result:

other: Survival was not affected by dietary treatment.

Details on results:

Weight gain was highest for fish fed diets supplemented with ≥367 mg/kg diet, followed by the 259 mg/kg diet, and lowest for fish fed the unsupplemented basal diet. Fish fed ≥367 mg/kg diet had higher food efficiency than fish fed the basal diet. Survival was not affected by dietary treatment. Test substance concentration in liver was highest in fish fed ≥479 mg/kg diet, followed by fish fed 259 and 167 mg/kg diets, and lowest in fish fed the basal diet. Hepatic lipid concentrations were higher in fish fed ≥367 mg/kg diet than fish fed ≤259 mg/kg diet. Growth performance, liver test substance, and lipid concentrations of fish fed the test substance-free diet containing the antibiotic were similar to that of fish fed the test substance-free diet without the antibiotic.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Survival of fish was not affected by dietary treatment with the test substance at doses up to 1200 mg/kg for 8 weeks. Growth and food consumption were increased at doses of ≥367 mg/kg.

Executive summary:

An 8-week growth experiment was conducted to estimate the dietary requirement of the test substance for juvenile hybrid tilapia. The test substance was supplemented at 0, 150, 250, 350, 450, 600, and 1200 mg/kg diet in the basal diet providing 0, 167, 259, 367, 479, 612, and 1253 mg/kg diet. Basal diet without test substance but with succinylsulfathiazole to suppress inositol synthesis by intestinal bacteria was included for comparison. Each diet was fed to triplicate groups of tilapia. Fish fed ≥367 mg/kg diet had significantly higher weight gain, followed by fish fed 259 mg/kg diet, and lowest for fish fed the unsupplemented basal diet. Fish fed ≥367 mg/kg diet had higher feed efficiency than fish fed the basal diet. Supplementation of dietary test substance did not affect survival of tilapia. Test substance concentrations in liver were highest in fish fed the ≥479 mg/kg diet, followed by fish fed the 259 and 167 mg/kg diets, and lowest in fish fed the basal diet. Hepatic lipid concentrations were higher in fish fed 367 mg/kg diet than fish fed ≤259 mg/kg diet. Weight gain percentage and test substance concentrations in the liver for the different treatments were analyzed by broken-line regression and indicated that the requirement for dietary inositol in growing tilapia is about 400 mg/kg diet. Addition of an antibiotic to basal diet did not affect the growth and hepatic inositol concentration of tilapia, suggesting that the intestinal microbial synthesis was not a significant source of inositol for tilapia.