Barium dibenzoate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: other: chromosomal effects

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study predates approved guidelines and GLP.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1974

Report date:

1973

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)

Principles of method if other than guideline:

Study predates approved guidelines.
The dominant lethal assay was performed using male rats at three dose levels. After treatment each male rat was mated with two females during for 5 days/week (7-8 weeks in total -> 14-16 females/male). Fourteen days after the end of the mating period females were killed and corpora lutea, early fetal deaths, late fetal deaths and total implantations per uterine horn were recorded.

GLP compliance:

no

Type of assay:

rodent dominant lethal assay

Test material

Test material information

Constituent 1

Reference substance name:

Sodium benzoate

EC Number:

208-534-8

EC Name:

Sodium benzoate

Cas Number:

532-32-1

IUPAC Name:

sodium benzoate

Constituent 2

Reference substance name:

Benzoic acid, sodium salt

IUPAC Name:

Benzoic acid, sodium salt

Details on test material:

No data given

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: A closed colony (random bred)
- Age at study initiation: 10 to 12 weeks old
- Weight at study initiation: 280 to 350 g
- Assigned to test groups randomly: yes
- Fasting period before study:
- Housing: Housed one to five to a cage, sanitary cages and bedding were used.
- Diet (e.g. ad libitum): Commercial 4% fat diet and provided ad libitum.
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 4-11 days

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

Saline

Details on exposure:

Ten male rats were assigned to each of 5 groups; 3 dose levels selected, a positive control (TEM) and a negative control (solvent only). The positive control was administered intraperitoneally. Administration of the test compound was orally by intubation in both the acute study (1 dose) and in the subacute study (1 dose per day for 5 days). Following treatment, the males were sequentially mated to 2 females per week for 8 weeks (7 weeks in the subacute study). Two virgin female rats were housed with a male for 5 days (Monday through Friday). These two females were removed and housed in a cage until killed. The male was rested on Saturday and Sunday and two new females introduced to the cage on Monday.

Duration of treatment / exposure:

Acute study: Immediately
Subacute study: 96h

Frequency of treatment:

Acute study: 1 dose
Subacute study: 1 dose per day for 5 days

Post exposure period:

14 days after separating from the male

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

50 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

500 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

5 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

Ten males and twenty females/week

Control animals:

yes, concurrent vehicle

Positive control(s):

Triethylene Melamine: 0.3 mg/kg

Examinations

Tissues and cell types examined:

Corpora lutea, early fetal deaths, late fetal deaths and total implantations per uterine horn.

Evaluation criteria:

statistical evaluation

Statistics:

The following statistical analyses were employed as a means of analyzing the results of the dominant lethal studies.
a. The fertility index
The number of pregnant females/number of mated females with the chi-square was used to compare each treatment to the control. Armitage's trend was used for linear proportions to test whether the fertility index was linearly related to arithmetic or log dose.

b. Total number of implantations
The t-test was used to determine significant differences between average number of implantations per pregnant female. Regression techniques were used to determine whether the average number of implantations per female was related to the arithmetic or log dose.

c. Total number of corpora lutea
The t-test was used to determine significant differences between average number of corpora lutea per pregnant female.

d. Preimplantation losses
Freeman-Tukey transformation was used on the preimplantation losses for each female and then the t-test was used to compare each treatment to control. Regression technique was used to determine whether the average number of preimplantation losses per female was related to the arithmetic or log dose.

e. Dead implants
Same as d.

f. One or more dead implants
The proportion of females with one or more dead implants was computed, each treatment compared to control by chi-square test and Armitage's trend used for linear proportions to see if proportions were linearly related to either arithmetic or log dose. Probit regression analysis was used to determine whether the probit of the proportions was related to log dose.

g. Two or more dead implants
Same as f.

h. Dead implants per total implants
Dead implants per total implants were computed for each female and used Freeman-Tukey arc-sine transformation on data for each female; then used t-test to compare each treatment to control .

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

All comparisons indicated below are with the negative control groups. Positive controls showed the expected results.

Fertility index
Acute: A significant increase was observed for the high dose of week 6. The intermediate and high dose levels of week 7 show a significant, dose-related decrease.
Subacute: Significant, dose-related increases were observed at week 1. Significant, dose-related decreases were observed at all dose levels of week 7. The low dose of week 2 was significantly higher than the negative control.

Average number of implantations/pregnant female
Acute: Significant, dose-related decreases were observed at the intermediate and high dose levels for weeks 3 and 7. Significant decrease was observed at the high dose of week 1.
Subacute: Week 6 showed a highly significant, dose-related increase. Significant increases were also observed at the low and intermediate dose levels of weeks 5 and 7 respectively. The only significant decrease was found at the low dose of week 2.

Average corpora lutea/pregnant female
Acute: Significant and dose-related decreases were seen at the intermediate and high dose levels of weeks 1 and 3. A significant decrease was also observed at the low dose of week 8.
Subacute: The only significant decrease was seen at the low dose of week 2. Significant, dose-related increases were obtained at all three doses of weeks 6 and 7. The low dose of week 5 was significantly higher than the control.

Average pre-implantation losses/pregnant female
Acute: All three doses of week 8 showed significant, dose-related decreases. Significant, dose-related increases were obtained for all dosed at week 7. The low dose of week 3 also showed a significant increase.
Subacute: Significant increases were observed at a number of weeks. All doses at week 6 showed dose-related increases. The low and intermediate doses of weeks 3 and 7 showed increases as well as the low dose of week 1 and the intermediate dose of week 5.

Average resorptions/pregnant female
Acute: Significant, dose related increases were observed at the low and high doses of week 2. The low and intermediate doses of week 7 were significantly increased over the negative control.
Subacute: No significant increases were observed. The high dose of week 2 showed a significant decrease.

Proportion of females with one or more dead implants
Acute: The low and high doses of week 2 showed significant increases as well as of intermediate dose of week 7.
Subacute: No significant findings.

Proportion of females with two or more dead implants
Acute: No significant findings.
Subacute: No significant findings.

Dead implants/total implants
Acute: Significant increases were observed at week 7 for the low and intermediate doses and week 2 for the low doses.
Subacute: No increases. The high dose of week 2 was significantly lower than the negative control.

Any other information on results incl. tables

No abnormalities were reported during treatment.

No gross morphological changes during necropsy on day 10

Applicant's summary and conclusion

Conclusions:

The test substance was considered to be non-mutagenic in rats in the Dominant Lethal Assay when using the dosages employed in this study.
Reliability of this study can be demonstrated as 2 (reliable with restrictions) due to limited data available on methods and results. Study predates approved guidelines and GLP.

Executive summary:

In a dominant lethal assay, sodium benzoate was evaluated in rats. Male rats (10/group) received 50, 500 and 5000 mg/kg bw as a single dose or on 5 consecutive days by gavage. After treatment each male rat was mated with two females per week for 7 -8 weeks (total 14 -16 females/male). Females were examined for number of corpora lutea, early fetal deaths, late fetal deaths and total implantations per uterine horn 14 days after the mating period.

The test substance did not show any consistent statistical significant effects on the parameters indicated above compared to negative controls. Positive controls performed as expected. Therefore the result in this dominant lethal test is considered to be negative.

Reliability of this study can be demonstrated as 2 (reliable with restrictions) due to limited data available on methods and results. Study predates approved guidelines and GLP.