Ammonium dihydrogen citrate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to a protocol that is similar to an appropriate OECD test guideline, with acceptable restrictions.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1975

Report date:

1975

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Deviations:

yes

Remarks:

Limited details on test animals and environmental conditions, only 50 cells per animal were scored for aberrations.

GLP compliance:

no

Type of assay:

other: in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Test material

Test material information

Constituent 1

Reference substance name:

Citric acid

EC Number:

201-069-1

EC Name:

Citric acid

Cas Number:

77-92-9

Molecular formula:

C6H8O7

IUPAC Name:

citric acid

Test material form:

solid: granular

Details on test material:

Compound FDA 71-54, Citric acid
U.S.P. Control Number 121M231 IV, as supplied by the Food and Drug Administration

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Flow Laboratories random-bred, closed colony
- Age at study initiation: 10 to 12 weeks
- Weight at study initiation: 280 to 350 g
- Assigned to test groups randomly: yes
- Fasting period before study: no data
- Housing: Rats were housed one to five to a cage
- Diet: Free access to commercial 4% fat diet
- Water: Free access to water
- Acclimation period: 4 - 11 days

ENVIRONMENTAL CONDITIONS
No data

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle used: physiol. saline
- Justification for choice of vehicle: no data

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The substance was suspended in 0.85% saline.

Duration of treatment / exposure:

6, 24 and 48 hours

Frequency of treatment:

Single dose

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

1.2 mg/kg bw/day

Remarks:

test 1

Doses / concentrations 2

Dose / conc.:

12 mg/kg bw/day

Remarks:

test 1

Doses / concentrations 3

Dose / conc.:

120 mg/kg bw/day

Remarks:

test 1

Doses / concentrations 4

Dose / conc.:

300 mg/kg bw/day

Remarks:

test 2

Doses / concentrations 5

Dose / conc.:

500 mg/kg bw/day

Remarks:

test 2

Doses / concentrations 6

Dose / conc.:

3 000 mg/kg bw/day

Remarks:

test 2

Doses / concentrations 7

Dose / conc.:

3 500 mg/kg bw/day

Remarks:

test 2

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

Positive control(s):

Triethylene Melamine, 0.3 mg/kg bw.

Examinations

Tissues and cell types examined:

Fifty metaphase spreads in bone marrow cells were scored per animal.

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: Based on toxicity test data.

DETAILS OF SLIDE PREPARATION: Four hours after the last substance administration, and two hours prior to killing, each animal was given 4 mg/kg bw colcemid intraperitoneally in order to arrest the bone marrow cells in c-mitosis. Animals were killed by using CO2, and the adhering muscle and epiphysis of one femur were removed. The cells were suspended in HBSS, centrifuged and resuspended in a hypotonic KCl solution. After incubation at 37°C, the cells were centrifuged and fixated in methanol/acetid acid and after overnight incubation resuspended and 2-3 drops of the suspension were allowed to drop onto a clean, dry slide and allowed to dry at room temperature overnight. The slides were stained using a 5% Giemsa solution, mounted and covered with a coverglass.

METHOD OF ANALYSIS: The specimens were scanned with 10x and 24x objectives and suitable metaphase spreads were examined using oil immersion flatfield apochromatic objectives. The chromosome of each cell were counted and only diploid cells were analyzed. Fifty metaphase spreads were scored per animal.

OTHER: Mitotic indices were obtained by counting at least 500 cells and the ratio of the number of cells in mitosis/the number of cells observed was expressed as the mitotic index.

Results and discussion

Test results

Key result

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
Dose range test 1: 100, 250, 500, 1000, 2000, 3000 mg/kg. One animal died at 500 mg/kg bw, 2 animals died at 1000 mg/kg bw and 3 animals died at 2000 and 3000 mg/kg bw. The LD50 was determined as 1700 mg/kg bw.
Dose range test 2: 5000 mg/kg, no deaths occurred. The LD50 was determined as >5000 mg/kg bw.

RESULTS OF DEFINITIVE STUDY
The substance produced no detectable significant aberration of the bone marrow metaphase chromosomes of rats.

Applicant's summary and conclusion

Conclusions:

An in vivo bone marrow chromosome aberration study with Citric acid was performed equivalent to OECD 475 guideline, in male rats. It is concluded that the substance is not mutagenic in the in vivo bone marrow chromosome aberration assay.

Executive summary:

An in vivo bone marrow chromosome aberration test was performed with Citric acid equivalent to OECD 475 guideline without GLP.

Groups of 5 male rats were orally administered to the test substance up to and including 3500 mg/kg bw for 6, 24 and 48 hours in two independently performed experiments. Reliable vehicle controls and positive controls were included. No treatment-related increase in the number of cells with aberrations were observed. It is concluded that the substance is not mutagenic in the in vivo bone marrow chromosome aberration assay.