Barium nitrate

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Study well documented, meets generally accepted scientific principles, acceptable for assessment. Deviations when comparing to OECD421: dosing only prior to mating, no individual animal data/tables provided, histopathologic examination, data on food consumption only provided for core study animals, no humidity, sex of pups, and data on stability of test substance in vehicle given. Only the average results of the controls and the high dose groups of each species were available.

Data source

Reference

Reference Type:

publication

Title:

Subchronic toxicity of barium chloride dihydrate administered to rats and mice in the drinking water

Author:

Dietz DD, Elwell MR, Davis WE, Meirhenry EF

Year:

1992

Bibliographic source:

Fundamental and applied toxicology 19, 527-537

Materials and methods

Principles of method if other than guideline:

In parallel with a subchronic toxicity core study, a premating study was performed with separate groups of rats and mice. Premating exposure period with barium chloride dihydrate was 60 days for males and 30 days for females.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Barium chloride

EC Number:

233-788-1

EC Name:

Barium chloride

Cas Number:

10361-37-2

Molecular formula:

BaCl2

IUPAC Name:

barium dichloride

Details on test material:

- Name of test material (as cited in study report): BaCl2.2H2O
- Analytical purity: 99.5% (EDTA titration)
- Lot/batch No.: 123120
- Other: source: Baker Chemical Co.

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Simonsen Laboratories (Gilroy, CA)
- Age at study initiation: 32 days old
- Housing: five per cage in drawer-type polycarbonate cages. The shelves supporting the cages were covered with filter sheets.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: The animals were quarantined for 10 to 11 days after arrival, and representatives were necropsied to verify that they were grossly free of disease.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 - 24°C
- Air changes (per hr): 13.5 room vol/hour
- Photoperiod (hrs dark / hrs light): 12 hours on (from 06h30 to 18h30) and 12 hours off

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Solutions were made weekly in 19-liter quantities by dissolving weighed portions of the chemical in distilled water.

Details on mating procedure:

The mating trials and fertility cytological evaluations were performed on separate groups of rats and then used in the core study.
After 60 days of exposure, the males were placed in individual cages and one female receiving the same dose level (but exposed for 30 days) was cohabited with each male for up to 1 week. Each morning following a day of cohabition, each female was examined for the presence of microscopic evidence of sperm in a vaginal swab. When evidence of mating was found, the female was separated from the male; after mating, determinations were made on the eighth day of cohabitation, all remaining pairs were separated. Females were weighed when evidence of mating was found and on the day of parturition.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The test substance was analyzed by EDTA titration. Dosage analyses performed on all levels before and after use, and at the beginning and midway through the test period, indicated that the concentrations were within 1 to 6% of the theoretical concentration.

Duration of treatment / exposure:

60 days (males), 30 days (females)

Frequency of treatment:

Exposures were continuous

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 ppm

Remarks:

nominal in water

Doses / concentrations 2

Dose / conc.:

1 000 ppm

Remarks:

nominal in water

Doses / concentrations 3

Dose / conc.:

2 000 ppm

Remarks:

nominal in water

Doses / concentrations 4

Dose / conc.:

4 000 ppm

Remarks:

nominal in water

No. of animals per sex per dose:

20

Control animals:

yes, concurrent no treatment

Positive control:

Not requiered

Examinations

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- All animals were observed twice daily for clinical signs of toxicity.

BODY WEIGHT: Yes
- Body weights were determined weekly

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Water consumptions were measured twice weekly.

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: No

CLINICAL CHEMISTRY: No

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

OtHER: Complete exams were performed in the parallel animal groups which were not used for reproductive and fertility assessment.

Oestrous cyclicity (parental animals):

Evaluation of vaginal cytology was performed among treated and control groups.

Sperm parameters (parental animals):

An evaluation of sperm morphology, density and motility among treated and control groups were performed according to methods described y Morrisey et al. 1988.
Morrisey RE, Schwetz BA, Lamb JC IV, Ross MD, Teague JL, Morris RW (1988). Evaluation of rodent sperm, vaginal cytology, and reproductive organ weight data from National Toxicology Program 13-week studies. Funda. Appl. Toxicol. 11; 343-358

Litter observations:

Live offspring were weighed, counted, and examined on day 0 (day of birth) and again on day 5.

Postmortem examinations (parental animals):

All females were terminated on days 96 and 97; the vagina, cervix, oviducts, and ovaries were grossly examined and the implantation sites in the uteri were counted.
An evaluation of male reproductive organ weights (testis, epidimymal) among treated and control groups were performed according to methods described y Morrisey et al. 1988.
Morrisey RE, Schwetz BA, Lamb JC IV, Ross MD, Teague JL, Morris RW (1988). Evaluation of rodent sperm, vaginal cytology, and reproductive organ weight data from National Toxicology Program 13-week studies. Funda. Appl. Toxicol. 11; 343-358

Postmortem examinations (offspring):

Dead pups were recovered from the nest and examined for external abnormalities.

Statistics:

Each parameter for which individual values were available was subjected to a linear least squares regression over the dose levels and the direction of the slope and the p value indicating the significance of the deviation of the slope from 0 was determined. Group means and standard deviations or standard errors were calculated from continuous variables. The multiple comparison procedure of Dunnett was employed for pairwise comparisons of these variables between dosed groups and controls. Fisher's exact test was used to make pairwise comparisons of discrete variables between dosed groups and controls and the Cochran-Armitage test was used to assess the significance of dose-related trends. Temporal and dose-related variations were evaluated using a repeated measures analysis of variance. When a collection of measurements was made on each animal, a multivariate analysis of variance was used to test for simultaneous equality of measurements across dose levels.

Reproductive indices:

determination of pregnancy rates in dosed and control animals
determination of average gestation period

Offspring viability indices:

no details stated

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

not specified

Food consumption and compound intake (if feeding study):

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

not examined

Description (incidence and severity):

Complete histologic exams were performed in the parallel animal groups which were not used for reproductive and fertility assessment.

Other effects:

not examined

Description (incidence and severity):

Test substance intake: only determined for core study animals

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
One pregnant dam in the 4000 ppm group was terminated in a moribund state 21 days after mating

BODY WEIGHT (PARENTAL ANIMALS): no data

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS)
No effect of BaCl2.2H2O could be detected on epididymal sperm counts, sperm motility, sperm morphology.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Although the pregnancy rates for the rat studies (from 40% in controls to 65% in the 4000 ppm group) were below the generally accepted norms for reproduction studies, this problem was not corrected by remating due to restrictions in the study dosing schedule/design. All pregnant dams produced live litters except for one in the 4000 ppm group which was terminated in a moribund state 21 days after mating; necropsy revealed seven fetuses and one resorption site. The average gestation period of surviving dams was 22 to 22.5 days in the various groups.

ORGAN WEIGHTS:
No effect of BaCl2.2H2O could be detected on testis or epididymal weight, or vaginal cytology at the dose levels evaluated up to 4000 ppm.

REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS)
No effect of BaCl2.2H2O could be detected vaginal cytology at the dose levels evaluated up to 4000 ppm.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study)
Water consumption was decreased in rats at some dose levels. Rats consumed approximately 70%.

Effect levels (P0)

Dose descriptor:

NOEL

Effect level:

4 000 ppm (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on a lack of effects on epididymal sperm counts, sperm motility, sperm morphology, testis or epididymal weight, vaginal cytology

Results: F1 generation

General toxicity (F1)

Clinical signs:

not specified

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

not specified

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

VIABILITY (OFFSPRING)
The average live litter size at birth and on postpartum day 5 was marginally reduced in the high-dose group (4000 ppm) rats compared with controls (day 0, 9.0 ± 1.37 pups compared to 7.2 ± 0.52 pups; day 5, 9.3 ± 1.16 pups compared to 7.1 ± 0.56 pups) due to the lack of statistical significance at p < 0.05. Pup survival to day 5 was 99% or greater in all rat treatment groups.

BODY WEIGHT (OFFSPRING)
In the high-dose group, the live pup weight at birth (5.20 ± 0.06 g) was significantly less (p < 0.01) than the control values (5.70 ± 0.09 g). A comparison of pup weights on day 5 (9.93 ± 0.20 g for high dose compared to 10.55 ± 0.26 g for controls) failed to show significant changes. Weight gain during this period, however, was comparable among all pup groups.

GROSS PATHOLOGY (OFFSPRING)
No external abnormalities were observed in the rat offspring.

Effect levels (F1)

Dose descriptor:

NOEL

Generation:

F1

Effect level:

4 000 ppm (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Based on a lack of effects on litter size at birth and on postpartum day 5, and on live pup weight at birth

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The no effect level for barium toxicity in this study is 4000 ppm ( 201.5 and 179.5 mg Ba/kg bw/d to male and and female rats, respectively) for the reproductive toxicity (Parent animals).
The no effect level for barium toxicity in this study 4000 ppm for the offspring.