Barium nitrate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

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.

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

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

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

Dose / conc.:

0 ppm

Remarks:

nominal in water

Dose / conc.:

1 000 ppm

Remarks:

nominal in water

Dose / conc.:

2 000 ppm

Remarks:

nominal in water

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

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

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: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

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%.

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

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

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.

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

Reproductive effects observed:

not specified

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.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

341.6 mg/kg bw/day

Study duration:

subacute

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Toxicity to reproduction:

Dietz D. D. et al (1992), evaluated the toxicity of the read-across substance barium chloride dihydrate in rats exposed for 60 days (males) and 30 days (females). The test item was administered in the drinking water at doses of 0 (controls), 1000, 2000 and 4000 ppm. The test was performed in parallel to a subchronic study.

One pregnant dam in the 4000 ppm group was sacrified in a moribound state 21 days after mating. No effects were observed in body weight, estrous cycle, sperm measures, reproductive performance, organs weights and gross pathology of parental animals. No histophatological observations were performed at necropsy but in a parallel animal groups from the core study (subchronic) which were not used for reproductive and fertility assessment.

No effects were observed in body weights and gross pathology of the 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.

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) or recalculated for barium nitrate 383.4 and 341.6 mg barium nitrate/kg bw/day (male and and female rats, respectively).
The no effect level for barium toxicity in this study 4000 ppm for the offspring.

This study was selected as it provides the lowest NOEL compared to the mice by Dietz, D D et al (1992).

This study is considered a K2 study to reflect the read-across from barium dichloride dihydrate to barium nitrate. The read across justification is added in Section 13 of IUCLID.

Dietz, D D et al (1992), also evaluated the toxicity of the read-across substance barium chloride dihydrate in mice. Animals were exposed to the test item for 60 days (males) and 30 days (females). The test item was administered in the drinking water at doses of 0 (controls), 500, 1000 and 2000 ppm. The test was performed in parallel to a subchronic study. Taken together all data of this study, there are no indications of a substantial impairment of fertility in mice up to the highest dose tested. Thus, the NOEL was 2000 ppm (to average doses of 206 and 199.8 mg Ba/kg bw/d to male and and female mice, respectively). No-observed-adverse-effect level (NOEL) on developmental toxicity for mice of 2000 ppm was derived from this study.

Annex IX testing: A testing proposal for an extended one-generation reproductive toxicity study (OECD Guideline 443) is included in the 2010 REACH dossier of the read-across substance barium chloride. In case the testing proposal will be approved and the test conducted, the results of barium chloride will be used to cover this endpoint for barium nitrate via read-across. Therefore, and in order to reduce the number of animals used, it is not necessary to perform an additional toxicity study with barium nitrate. A justification for read-across has been written and the document is added to section 13 of this dossier.

Short description of key information:
Toxicity to Reproduction:
Dietz D D et al (1992), evaluated the toxicity of the read-across substance barium chloride dihydrate in rats exposed for 60 days (males) and 30 days (females). The test item was administered in the drinking water at doses of 0 (controls), 1000, 2000 and 4000 ppm. The NOEL 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) or recalculated for barium nitrate 383.4 and 341.6 mg barium nitrate/kg bw/day (male and and female rats, respectively). The no effect level for barium toxicity in this study 4000 ppm for the offspring.

In a supportive study, the potential toxicity of the read-across substance barium nitrate was evaluated in mice by Dietz D D et al (1992). The NOEL was 2000 ppm (to average doses of 206 and 199.8 mg Ba/kg bw/d to male and and female mice, respectively). No-observed-adverse-effect level (NOEL) on developmental toxicity for mice of 2000 ppm was derived from this study.

Justification for selection of Effect on fertility via oral route:
No study available with barium nitrate. The selected study is the most reliable study with read-across susbtance barium chloride dihydrate.

Justification for selection of Effect on fertility via inhalation route:
Only one route of exposure is needed for this endpoint.

Justification for selection of Effect on fertility via dermal route:
Only one route of exposure is needed for this endpoint.

Effects on developmental toxicity

Description of key information

a NOAEL of >=85.3 mg BaCl2/kg or >=107.1 mg barium nitrate/kg was derived in an oral developmental toxicity study according to OECD 414.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-11-24 to 2013-12-19

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

adopted 2001-01-22

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.31 (Prenatal Developmental Toxicity Study)

Version / remarks:

, 2004

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2013-07-09

Limit test:

no

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS- RccHan: WIST strain
- Source: Harlan, Horst, the Netherlands
- Age at study initiation: approx. 12 weeks of age
- Weight at study initiation: control group: 197.9 - 230.9 g; low dose group: 198.1 - 230.2 g; mid dose group: 190.9 - 232.5 g; high dose group: 191.6 - 239.4 g
- Housing: animals were housed in Macrolon cages with a bedding of wood shavings (Lignocel) and strips of paper (Enviro-dri) and a wooden block as environmental enrichment. During the quarantine and acclimatization periods, the animals were housed in groups of 4 per sex. Mated females were housed individually in Macrolon cages.
- Diet (ad libitum): cereal-based (closed formula) rodent diet (Rat & Mouse No.3 Breeding Diet; RM3) (supplier: SDS Special Diets Services, Witham, England)
- Water (ad libitum): domestic mains tap-water
- Quarantine period: 9 days (upon arrival the rats were quarantined and checked for overt signs of ill health and abnormalities. During the quarantine period, serological examinations of the microbiological status of the rats were conducted in a random sample.)
- Acclimation period: 2 days

ENVIRONMENTAL CONDITIONS
- Temperature: 20 - 24°C
- Relative humidity: exceeded 65% for short times only during cleaning activities
- Air changes: about 10 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

other: demineralized water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Solutions of the test item in the vehicle were prepared weekly, and stored in a refrigerator (2-10°C) in the dark in aliquots sufficient for one day. The vehicle for dosing the controls was similarly stored.
The solutions of the test item in the vehicle were prepared by stirring on a magnetic stirrer. Subsequently, 8 aliquots (7 days plus 1 extra) were taken per dose level according to the daily volume required for each dosing. These aliquots were taken under continuous stirring. On each subsequent day, one aliquot for each group was removed from the refrigerator and allowed to equilibrate to ambient temperature prior to dosing.

A dosing volume of 10 mL/kg was applied for all animals, which was adjusted based on the latest body weight. After gestation day 14 dose volumes were not adjusted.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

From all three batches of the test items prepared in the study, samples were taken immediately after preparation and stored in a refrigerator until analysis. The following analyses were conducted by Inductively coupled plasma atomic emission spectrometry (ICP-AES) analysis. The test item was quantified using barium as a marker component:
- Homogeneity: the homogeneity of the test substance in the experimental test items was demonstrated in the first batch prepared, by analysing three samples (taken at different locations in the gavage liquid container) of each level.
- Concentration: the concentration of test substance at each level was determined in all three batches of test items prepared in the study.
- Stability: samples of the low-dose, mid-dose and high-dose level were analysed in the first batch prepared in the study at t=0 and after storage in the refrigerator (2 – 10 °C) for twelve days.

Results:
- Homogeneity: the relative standard deviations between the mean content at three different locations was < 5% in the low, mid and high dose level. Therefore barium chloride dihydrate was considered to be homogeneously distributed in each test.
- Stability: upon storage at refrigerator temperature from 22 November 2013 till 4 December 2013, the relative difference in test substance concentration between t=0 and t=4 days was -3.6, +1.5 and +4.2% in the low, mid and high dose level, respectively. And all the dose levels met the criteria for stability (relative difference ≤10%). Therefore it was concluded that there was no loss of test substance from any tests items during storage for twelve days in the refrigerator.
- Content: the content of barium chloride dihydrate determined in the test items are compared with the intended content. The relative difference between the mean determined content and the intended content was between 1.5 and 2.5% at all nominal levels of 1, 3 and 10 mg/ml which was within the acceptance criteria (relative difference ≤10%). Therefore, the actual content was considered to meet the intended level in each test item.

Details on mating procedure:

- Impregnation procedure: cohoused
- M/F ratio per cage: 2 females : one male
- Length of cohabitation: until a sperm positive smear was detected
- Proof of pregnancy: sperm in vaginal smear referred to as gestation day 0 of pregnancy

Duration of treatment / exposure:

gestation day 0 up to and including gestation day 20

Frequency of treatment:

daily

Duration of test:

25 days

No. of animals per sex per dose:

24 mated female rats

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The dose levels have been selected in consultation with the study monitor on the basis of a dose range finding study with the test item in pregnant rats.
During the dose range finding study groups of 5 mated females, were administered different dose levels of the test substance by gavage from gestation day 0 up to gestation day 21. A dose volume of 10 mL/kg body weight was applied and demineralized water was used as vehicle and control item. Dose levels of 0, 50, 175 and 250 mg/kg were administered.
Based on the preterm death of 3/5 females in the high dose group and 2/5 females in the mid dose group after a single dose, dosing was discontinued in both groups.
All surviving animals in the mid and high dose group were re-allocated to a new mid dose group and received 100 mg/kg body weight barium chloride from gestation day 2 onwards.
On gestation day 21 the animals were sacrificed and caesarean section was performed.
In-life parameters included clinical signs, morbidity, mortality, body weight and food consumption. At sacrifice uterus weight, number of corpora lutea, number of implantation sites, early and late resorptions, number of live and dead foetuses and foetus weight were recorded. In addition, foetuses were examined for external abnormalities/malformations and dams were observed for gross anatomical changes.

Results:
Oral administration of 0, 50, 100, 175 and 250 mg/kg barium chloride to mated females resulted in:
- the preterm death of 3/5 animals in the 250 mg/kg group and 2/5 animals in the 175 mg/kg group after a single oral dose.
- the spontaneous death of one animal in the 100 mg/kg group on gestation day 21. This animal was found dead before cesarean section and had 11 dead foetuses. This animal had received one dose of 250 mg/kg on gestation day 0 and daily doses of 100 mg/kg from gestation day 2 to 21.
- limited clinical observations in the 250 and 175 mg/kg group, including hunched posture an piloerection.
- no effect on body weight or body weight gain, food consumption, mean number of corpora lutea, implantation sites, early and late resorptions and the mean number of live foetuses.
- although based on a limited number of litters (four in the 50 mg/kg group and three in the 100 mg/kg group) an effect on foetus weight could not be ruled out.
- no foetuses showing external malformations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations: clinical signs and mortality

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: gestation days (GD) 0, 3, 6, 10, 14, 17 and 21

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes (gestation days 0-3, 3-6, 6-10, 10-14, 14-17 and 17-21)
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day #21
The females were killed by decapitation after CO2/O2 anaesthesia on gestation day 21 and examined for gross abnormalities.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Weight of empty uterus: Yes
- Weight of ovaries: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Gross evaluation of placentas: Yes
For seemingly non pregnant females (part of) the uterus was stained with Na2SO3 in order to visualize possible implantation sites (Salewski E, 1964). Upon staining non pregnancy was confirmed for these females.

Fetal examinations:

- External examinations: Yes
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: No

Further examinations:
- number of live and dead foetuses
- sex of the foetuses
- live foetuses (individually) and corresponding placentas
- foetal weight

Statistics:

Tests were generally performed as two-sided tests with results taken as significant where the probability of the results was p<0.05 or p<0.01.
Continuous data were subjected to the ‘Decision tree for continuous data’ and dichotomous data to the ‘Decision tree for dichotomous data’.

Indices:

For each group the following indices were calculated:
- female fertility index = (no. of pregnant females/no. of inseminated females) x 100
- pre-implantation loss = [(no. of corpora lutea – no. of implantation sites) / no. of corpora lutea] x 100
- post-implantation loss = [(no. of implantation sites – no. of live foetuses) / No. of implantation sites] x 100
- gestation index = (no. of females with live foetuses/no. of females pregnant) x 100
- sex ratio = (no. of live male foetuses/no. of live foetuses) x 100

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not specified

Mortality:

mortality observed, treatment-related

Description (incidence):

- two animals in the high dose group were found dead on day 21 of gestation. Both animals were pregnant and all foetuses were dead. Although death was not preceded by clinical signs, growth retardation or gross anatomical observations at necropsy that could clarify the death of these animals, the death of these rats is ascribed to treatment.
- one animal in the high dose group felt cold and was weakened and showed piloerection on gestation day 21. Upon necropsy this animal showed hydrothorax, haemorrhages in the liver and haemorrhagic discharge in the vagina. Also the death of this high-dose rat is ascribed to treatment.
- the spontaneous death of two rats, and the conditional decline of one rat on day 21 of gestation were considered to be treatment-related and to represent severe maternal toxicity in the high dose group.
- all foetuses were dead in the above three rats. The foetal deaths observed in these animals are considered to be related to the severe maternal toxicity in the high-dose group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

- no effects were observed on body weight.
- A slightly, but statistically significantly reduced body weight gain was observed in the high dose group as compared to the control group during the first three days of dosing. This was considered to be related to treatment and recovered thereafter.
- no effects on body weight or body weight gain were observed in the low dose group and the mid dose group as compared to the control group.

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Immunological findings:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

FEMALE REPRODUCTIVE ORGANS
- mean ovary weight, mean full and empty uterus weight were comparable in all groups
- mean carcass weight and net body weight change were comparable in all groups
- mean placenta weight was comparable in all groups

Gross pathological findings:

no effects observed

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

- 23, 22, 23 and 22 pregnant females in the control group, low dose, mid dose and high dose group, respectively.
- reproduction indices were comparable for the control, low dose, mid dose and high dose group
- no effects were noted in mean number of corpora lutea, mean number of implantation sites, preimplantation loss, mean number of early resorptions, late resorptions and mean number of live foetuses.

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

- 23, 22, 23 and 22 pregnant females in the control group, low dose, mid dose and high dose group, respectively.
- reproduction indices were comparable for the control, low dose, mid dose and high dose group
- no effects were noted in mean number of corpora lutea, mean number of implantation sites, preimplantation loss, mean number of early resorptions, late resorptions and mean number of live foetuses.

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Dose descriptor:

NOAEL

Remarks:

(barium chloride dihydrate)

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Remarks:

(barium chloride dihydrate)

Effect level:

>= 100 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Dose descriptor:

NOAEL

Remarks:

(barium chloride)

Effect level:

25.6 mg/kg bw/day

Based on:

other: barium dichloride

Basis for effect level:

other: maternal toxicity

Dose descriptor:

NOAEL

Remarks:

(barium chloride)

Effect level:

>= 85.3 mg/kg bw/day

Based on:

other: barium dichloride

Basis for effect level:

other: developmental toxicity

Abnormalities:

effects observed, treatment-related

Localisation:

other: mortality

Fetal body weight changes:

no effects observed

Description (incidence and severity):

FOETUS WEIGHT AND SEX
- mean foetus weight was comparable in all groups

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

- mean percentages male littermates was comparable in all groups

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

no effects observed

Description (incidence and severity):

- foetal external, visceral, and skeletal examinations did not reveal any treatment-related effects.

Dose descriptor:

NOAEL

Effect level:

> 100 mg/kg bw/day

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Developmental effects observed:

not specified

Conclusions:

Daily administration of barium chloride dihydrate at dose levels of 0, 10, 30 or 100 mg/kg body weight to pregnant rats from gestation day 1 up to and including gestation day 20, resulted in maternal toxicity as evidenced by the spontaneous deaths of two animals on gestation day 21 and the conditional decline of another animal on gestation day 21 in the high dose group. No developmental toxicity was observed.
The NOAEL for maternal toxicity was therefore 30 mg/kg body weight (recalculated for barium chloride: 25.6 mg/kg bw/day). In absence of developmental effects the NOAEL for prenatal developmental toxicity in the rat was ≥ 100 mg/kg body weight (recalculated for barium chloride: ≥ 85.3 mg/kg bw/day).

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

107.1 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study is fully acceptable

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Developmental toxicity of barium chloride dihydrate was evaluated in a recent prenatal developmental toxicity study by daily administration of the test item at dose levels of 0, 10, 30 or 100 mg BaCl₂ * 2 H₂O/kg body weight to pregnant rats from gestation day 1 up to and including gestation day 20. No effects on body weights, food consumption and clinical signs were observed. Maternal toxicity was evidenced by the spontaneous deaths of two animals on gestation day 21 only and the conditional decline of another animal on gestation day 21 in the high dose group (100 mg BaCl₂ * 2 H₂O/kg bw).

No developmental toxicity or treatment-related observations, whatsoever in external, visceral and skeletal foetal examinations were observed in any dose level.

The NOAEL for maternal toxicity was therefore 30 mg/kg body weight barium chloride dihydrate (25.6 mg/kg bw barium chloride or 32.1 mg/kg bw barium nitrate). In absence of developmental effects, the NOAEL for prenatal developmental toxicity in the rat was ≥ 100 mg/kg body weight barium chloride dihydrate (≥85.3 mg barium chloride/kg bw or ≥107.1 mg barium nitrate/kg bw).

Furthermore, tentative NOAEL values for developmental toxicity of 4,000 ppm and 2,000 ppm for rats and mice, respectively, are also reported in the study by Dietz et al. (1992). However, these NOAELs are of limited value to evaluate the potential for barium to induce developmental effects because the study design did not include prenatal exposure of the female animals to barium dichloride dihydrate. Therefore, this study has to be considered as inadequate for the assessment of the potential to induce developmental toxicity and cannot be used in a regulatory context.

Justification for selection of Effect on developmental toxicity: via oral route:
Barium dichloride dihydrate was evaluated recently in a GLP compliant oral prenatal toxicity study accorrding to OECD guideline 414. The NOAEL is reported as re-calculated barium nitrate

Justification for classification or non-classification

No classification is required based on the results of the prenatal developmental toxicity study.