Citric acid

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The tests were conducted to generally acceptable scientific standards, with acceptable restrictions, i.e. no mention of cytotoxic concentrations and positive controls; no appropriate 5th strain

Data source

Reference

Reference Type:

publication

Title:

Primary Mutagenicity Screening of Food Additives Currently Used in Japan.

Author:

Ishidate M J R, Sofuni T, Yoshikawa M, Hayashi T, Noshmi T, Sawada M, Matsuoka A

Year:

1984

Bibliographic source:

Fd Chem Toxic 22(8): 623-636

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

specific positive controls not included; no appropriate 5th strain included

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

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:

2-hydroxypropane-1,2,3-tricarboxylic acid

Details on test material:

- Name of test material (as cited in study report): citric acid
- Substance type: single component substance
- Analytical purity: 99.9%

Method

Target gene:

histidine operon

Species / strain

Species / strain / cell type:

S. typhimurium, other: TA 1535, TA 100, TA 98, TA 1537, TA92 and TA 94

Metabolic activation:

with and without

Metabolic activation system:

polychlorinated biphenyl induced rat liver S9

Test concentrations with justification for top dose:

Up to 5000 µg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: phosphate buffer
- Justification for choice of solvent/vehicle: sample soluble in water

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

other: control was exposed to appropriate solvent or untreated

True negative controls:

no

Positive controls:

other: specific controls not tested, but positive results obtained with some test substances screened

Positive control substance:

other: include Fast Green FCF (with activation), L cysteine monohydrochloride (with and without activation)

Details on test system and experimental conditions:

METHOD OF APPLICATION: preincubation

DURATION
- Preincubation period: 20 min
- Exposure duration: 48 hours
- Fixation time (start of exposure up to fixation or harvest of cells): 48 hours

NUMBER OF REPLICATIONS: duplicate plates were used

DETERMINATION OF CYTOTOXICITY
- Method: other: not described

Evaluation criteria:

The result was considered positive if the number of colonies found was twice the number in the control (exposed to the appropriate solvent or untreated). If no reasonable dose-response was found, the experiment was repeated using different doses.

Statistics:

No statistical analysis is described.

Results and discussion

Test results

Test results 1

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

other: positive results were obtained with some substances tested

Test results 2

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

other: positive results were obtained with some substances tested

Test results 3

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

other: positive results were obtained with some substances tested

Test results 4

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

other: positive results were obtained with some substances tested

Test results 5

Key result

Species / strain:

S. typhimurium, other: TA 92

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

other: positive results were obtained with some substances tested

Test results 6

Key result

Species / strain:

S. typhimurium, other: TA 94

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

not specified

Untreated negative controls validity:

not specified

Positive controls validity:

other: positive results were obtained with some substances tested

Applicant's summary and conclusion

Conclusions:

Citric acid has been tested in a bacterial reverse mutation assay conducted according to a protocol similar to OECD Test Guideline 471. No significant increase in the number of revertant colonies was detected in any Salmonella typhimurium strains TA 1535, TA 1537, TA98, TA 100, TA 92 and TA 94 at the maximum dose, using the preincubation method with and without metabolic activation. It is concluded that citric acid is negative for mutagenicity to bacteria under the conditions of this test.