Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
Circa 1988
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Data source

Reference
Reference Type:
publication
Title:
Micronucleus test in mice on 39 food additives and eight miscellaneous chemicals
Author:
Hayashi et al
Year:
1988
Bibliographic source:
Fd. Chem. Toxic. 26, No. 6, 487-500

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Micronucleus test conducted on a Japanese government laboratories: National Institute of Hygiene Sciences and Public Health Laboratory.
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium 1-(3,4-dihydro-6-methyl-2,4-dioxo-2H-pyran-3-ylidene)ethanolate
EC Number:
224-580-1
EC Name:
Sodium 1-(3,4-dihydro-6-methyl-2,4-dioxo-2H-pyran-3-ylidene)ethanolate
Cas Number:
4418-26-2
Molecular formula:
C8H7O4.Na
IUPAC Name:
sodium 1-(6-methyl-2,4-dioxo-2H-pyran-3(4H)-ylidene)ethanolate

Test animals

Species:
mouse
Strain:
other: ddy - from a Japanese breeder
Details on species / strain selection:
Used by the laboratories
Sex:
male
Details on test animals or test system and environmental conditions:
Eight-week-old male ddY mice (Shizuoka Agri-cultural Cooperative Association for Laboratory Animals, Shizuoka) were used at both laboratories, and were allowed food pellets CE-2 (Japan Clea, Tokyo) and water ad lib. throughout the experiments.

Administration / exposure

Route of administration:
other: Oral and intraperitoneal
Vehicle:
water or normal saline
Details on exposure:
See any other information on materials and methods below::
Duration of treatment / exposure:
See any other information on materials and methods below:
Frequency of treatment:
Multiple (four or five) injections with 24-hr intervals between the injections.
Post exposure period:
24 hours
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
See results for route of exposure for dosages
Dose / conc.:
37.5 mg/kg bw/day (nominal)
Dose / conc.:
62.5 mg/kg bw/day (nominal)
Dose / conc.:
75 mg/kg bw/day (nominal)
Dose / conc.:
125 mg/kg bw/day (nominal)
Dose / conc.:
150 mg/kg bw/day (nominal)
Dose / conc.:
250 mg/kg bw/day (nominal)
Dose / conc.:
300 mg/kg bw/day (nominal)
Dose / conc.:
500 mg/kg bw/day (nominal)
Dose / conc.:
1 000 mg/kg bw/day (nominal)
Dose / conc.:
1 250 mg/kg bw/day (nominal)
No. of animals per sex per dose:
2-6/group for the pilot and main test
Control animals:
yes, concurrent no treatment
Positive control(s):
Mitomycin C.
Additionally a number of substances were tested in this study, some of which were suspected to be genotoxic.

Examinations

Tissues and cell types examined:
See any other information on materials and methods below:
Details of tissue and slide preparation:
See any other information on materials and methods below:
Evaluation criteria:
See any other information on materials and methods below:
Statistics:
A two-stage statistical procedure was used: the frequency of MNPCEs in each treatment group was compared with the binomial distribution specified by historical control data. In the second stage, the dose-response relationship was tested by the Cochran-Armitage trend test. A positive result was recorded only when one or more treatment group(s) showed a statistically significant difference (P <0.01) from the spontaneous level of MNPCEs and the trend test indicated a positive dose response (P < 0.05).

Results and discussion

Test resultsopen allclose all
Sex:
male
Genotoxicity:
positive
Toxicity:
not specified
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Remarks on result:
other: intraperitoneal injection
Key result
Sex:
male
Genotoxicity:
negative
Toxicity:
not specified
Vehicle controls validity:
valid
Negative controls validity:
not valid
Positive controls validity:
valid
Remarks on result:
other: oral gavage
Additional information on results:
See attached table

Applicant's summary and conclusion

Conclusions:
Dehydroacetic acid, sodium salt DHA-Na, when dosed by oral gavage showed that there was no trend for genotoxicity. When dosed by the intraperitoneal route there was a positive trend for genotoxicity. However, as indicated in the OECD guideline 747, the appropriate route of exposure should be used, the appropriate route of potential exposure is most likely oral rather than intraperitoneal. The data therefore indicate that DHA-Na should be considered as not genotoxic.
Executive summary:

Dehydroacetic acid, sodium salt DHA-Na, when dosed by oral gavage, at dose levels between 37.5 and 1250 mg/kg showed that there was no positive trend for genotoxicity. When dosed by the intraperitoneal route there was a positive trend for genotoxicity. However, as indicated in the OECD guideline 747, the appropriate route of exposure should be used, the appropriate route of potential exposure is most likely oral rather than intraperitoneal.  The data therefore indicate that DHA-Na should be considered as not genotoxic.