Tetrabismuth triorthosilicate

Endpoint summary

Description of key information

Repeated dose toxicity. Oral route. Read across approach. An OECD 408 Repeat dose toxicity oral 90-day study in rats was conducted with bismuth subnitrate. Groups of male and female rats were treated daily by oral gavage at dose levels of 0 (control), 40, 200 or 1000 mg/kg/day which were dose levels based on a previous 28-day study in rats. Overall, all three dose levels were well tolerated and it was considered that a dose level of 1000 mg/kg/day could be assigned the No Observed Adverse Effect Level (NOAEL). Based on read across from the analogue bismuth subnitrate, the target substance tetrabismuth triorthosilicate can be considered to have a NOAEL = 760.7 mg/kg bw/day.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

8 May 2015 to 7 March 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

Deviations:

yes

Remarks:

See below for details.

Principles of method if other than guideline:

Deviations:
The target ranges for relative humidity and temperature were to be between 50 ± 20% and 22 ± 3°C, respectively. Instances of higher relative humidity were noted during this study on twenty three occasions between 17 June 2015 and 22 August 2015. During these episodes, the relative humidity ranged between 70.53 to 78.94% RH. One instance of lower temperature, where values ranged between 17.55 to 18.76 °C, was noted on 10 June 2015 whilst a single instance of
higher temperature (25.15 °C) was also noted on 01 July 2015. Although these episodes of higher relative humidity or lower/higher temperature were less than ideal, they were of short duration with the majority of relative humidity incidents and the single high temperature incident lasting for a maximum of up to two hours. The high temperature incident was considered to be due to a technical fault with the air conditioning system and specific measures were put into place immediately to rectify the situation on 01 July 2015 when the technical fault had occurred. The low temperature incident also occurred on one occasion only and lasted for a maximum of up to six hours. Clinical condition of the animals was considered to have remained unaffected by these episodes and this deviation from the Study Plan was therefore considered not to have any impact on the integrity of the study or results obtained.
According to the Study Plan, samples of the homogenate (from testis) were to be examined microscopically to determine the number of homogenisation resistant spermatids present. This was a typographical error in the Study Plan as an automated semen analyser is utilized at the Test Facility for this purpose. This deviation from the Study Plan therefore did not have any impact on the integrity of the study or results obtained.

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

other: Wistar Han™:RccHan™:WIST

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Oxon, UK.
- Age at study initiation: approximately six to eight weeks old.
- Weight at study initiation: the males weighed 198 to 238g, the females weighed 131 to 167g,
- Fasting period before study: Not specified
- Housing: The animals were housed in groups of three or four by sex in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd., Cheshire, UK).
- Diet: The animals were allowed free access to food. A pelleted diet (Rodent 2014C Teklad Global Certified Diet, Harlan Laboratories U.K. Ltd., Oxon, UK.) was used.
- Water: The animals were allowed free access to water. Mains drinking water was supplied from polycarbonate bottles attached to the cage.
- Acclimation period: The animals were acclimatized for at least nine days (before the start of treatment) during which time their health status was assessed.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): target range: 22 ± 3 °C. One instance of lower temperature, where values ranged between 17.55 to 18.76 °C, was noted on 10 June 2015 whilst a single instance of higher temperature (25.15 °C) was also noted on 01 July 2015. Clinical condition of the animals was considered to have remained unaffected by these episodes.
- Humidity (%): target range: 50 ± 20%
- Air changes (per hr): The rate of air exchange was at least fifteen air changes per hour.
- Photoperiod (hrs dark / hrs light): The low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness.
Environmental conditions were continuously monitored by a computerized system, and print-outs of hourly temperatures and humidities are included in the study records.

IN-LIFE DATES: From: To: 2 June 2015 (first day of treatment) and 11 September 2015 (final day of necropsy).

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water): Most of the lab's background data was with Arachis oil hence this was there preferred vehicle.
- Concentration in vehicle: At dose level of 40 mg/kg bw/day, concentration was 10 mg/ml. At dose of 200 mg/kg bw/day, the concentration was 50 mg/ml. At dose level of 1000 mg/kg bw/day, the concentration was 250 mg/ml.
- Amount of vehicle (if gavage): Treatment volume: 4 ml/kg
- Lot/batch no. (if required): Not provided
- Purity: Not provided

The test item was administered daily, for ninety consecutive days, by gavage using a stainless steel cannula attached to a disposable plastic syringe. Control animals were treated in an identical manner with 4 mL/kg of Arachis oil BP. The volume of test and control item administered to each animal was based on the most recent scheduled body weight and was adjusted at weekly intervals.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Since the method used for formulation analysis was non-stability indicating, test item formulation stability was not determined, and therefore, fresh formulations were prepared each day and dosed within two hours of preparation. It is assumed that the formulation was stable for this duration. As stability was not determined, this is an exception with regards to GLP and has been reflected in the GLP compliance statement. Homogeneity of the test item formulations was demonstrated by Harlan Laboratories Ltd., Shardlow, UK, Analytical Services.

Due to the complex nature of the test item and its limited solubility in organic and aqueous media, a substance specific quantitative method of analysis could not been developed. The concentration of test item in the formulations was determined using a gravimetric technique. The test item formulations were weighed into tared glass sintered crucibles and then rinsed with acetone to leave a test item residue. The samples were then dried in an oven at approximately 105 degrees C before allowing to cool over silica gel in a dessicator and re-weighed.

Samples of Arachis oil BP were accurately fortified with known amounts of test item equivalent to the lowest and highest anticipated dose concentrations.

The fortified samples of Arachis oil BP were found to have a recovery value of +/- 10% of the fortification.
The formulations investigated during the study were found to comprise test item in the range of 93% to 103% and thus the required content limit of +/- 10% with reference to the nominal content was met.

The results indicate the accurate use of the test item and Arachis oil BP as vehicle during the study. the formulations were found to be homogeneously prepared.

The analytical procedure had acceptable recoveries of test item in the vehicle. The method of analysis was validated and proven to be suitable for use.

Duration of treatment / exposure:

90 days

Frequency of treatment:

Once daily

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

ten animals per sex per dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Based on doses used in 28 day study with Bismuth (Sano et al., 2005)
- Rationale for animal assignment: The animals were randomly allocated to treatment groups using a stratified body weight randomization procedure and the group mean body weights were then determined to ensure similarity between the treatment groups. The cage distribution within the holding rack was also randomized. The animals were uniquely identified within the study by an ear punching system routinely used in these laboratories.
- Rationale for selecting satellite groups: Not applicable
- Post-exposure recovery period in satellite groups: Not applicable
- Section schedule rationale (if not random): Not applicable

Positive control:

None

Observations and examinations performed and frequency:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: All animals were examined for overt signs of toxicity, ill-health or behavioral change immediately before dosing, up to thirty minutes post dosing and one hour after dosing. All observations were recorded.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded on Day 1 (prior to dosing) and at weekly intervals thereafter. Body weights were also recorded at terminal kill.

FOOD CONSUMPTION AND COMPOUND INTAKE:
Food consumption was recorded for each cage group at weekly intervals throughout the study.

FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE: Yes
- Time schedule for examinations: Water intake was observed daily, for each cage group, by visual inspection of the water bottles for any overt changes.

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Pre-treatment and before termination of treatment (during Week 12). Examinations included observation of the anterior structures of the eye. Following pupil dilation with 0.5% Tropicamide solution (Mydriacyl® 0.5%, Alcon Laboratories (UK) Ltd., Pentagon Park, Boundary Way, Hemel Hampstead, Hertfordshire), detailed examination of the internal structure of the eye using a direct ophthalmoscope was performed.
- Dose groups that were examined: Th.e eyes of all control and high dose animals were examined

HAEMATOLOGY: Yes
- Time schedule for collection of blood: At the end of the study (Day 90). Blood samples were obtained from the lateral tail vein. Where necessary repeat samples were obtained by cardiac puncture prior to necropsy on Day 91.
- Anaesthetic used for blood collection: No data
- Animals fasted: No
- How many animals: All animals from each test and control group.
- Parameters examined.
Hemoglobin (Hb)
Erythrocyte count (RBC)
Hematocrit (Hct)
Erythrocyte indices - mean corpuscular hemoglobin (MCH), - mean corpuscular volume (MCV), - mean corpuscular hemoglobin concentration (MCHC)
Total leukocyte count (WBC)
Differential leukocyte count
- neutrophils (Neut)
- lymphocytes (Lymph)
- monocytes (Mono)
- eosinophils (Eos)
- basophils (Bas)
Platelet count (PLT)
Reticulocyte count (Retic)
- Methylene blue stained slides were prepared but reticulocytes were not assessed
Prothrombin time (CT) was assessed by ‘Innovin’ and Activated partial thromboplastin time (APTT) was assessed by ‘Actin FS’ using samples collected into sodium citrate solution (0.11 mol/L).

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: At the end of the study (Day 90). Blood samples were obtained from the lateral tail vein. Where necessary repeat samples were obtained by cardiac puncture prior to necropsy on Day 91.
- Animals fasted: No
- How many animals: All animals from each test and control group.
- Parameters examined:
The following parameters were measured on plasma from blood collected into tubes containing lithium heparin anti-coagulant:
Urea
Inorganic phosphorus (P)
Glucose Aspartate aminotransferase (ASAT)
Total protein (Tot.Prot.)
Alanine aminotransferase (ALAT)
Albumin Alkaline phosphatase (AP)
Albumin/Globulin (A/G) ratio (by calculation)
Creatinine (Creat)
Sodium (Na+)
Total cholesterol (Chol)
Potassium (K+)
Total bilirubin (Bili)
Chloride (Cl-)
Bile acids
Calcium (Ca++)

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Prior to the start of treatment and at weekly intervals thereafter, all animals were observed for signs of functional/behavioral toxicity. During Week 12 functional performances tests were also performed on all animals together with an assessment of sensory reactivity to different stimuli.
- Dose groups that were examined: All animals.
- Battery of functions tested:
Detailed individual clinical observations were performed for each animal using a purpose built arena. The following parameters were observed:
Gait
Hyper/Hypothermia
Tremors
Skin color
Twitches
Respiration
Convulsions
Palpebral closure
Bizarre/Abnormal/Stereotypic behavior
Urination
Salivation
Defecation
Pilo-erection
Transfer arousal
Exophthalmia
Tail elevation
Lachrymation

This test was developed from the methods used by Irwin (1968) and Moser et al (1988). The scoring system used is outlined in The Key to Scoring System and Explanation for Behavioral Assessments and Sensory Reactivity Tests.

Functional Performance Tests
Motor Activity. Twenty purpose built 44 infra-red beam automated activity monitors were used to assess motor activity. Animals of one sex were tested at each occasion and were randomly allocated to the activity monitors. The tests were performed at approximately the same time each occasion (at least two hours after dosing), under similar laboratory conditions. The evaluation period was one hour for each animal. The time in seconds each animal was active and mobile was recorded for the overall one hour period and also during the final 20% of the period (considered to be the asymptotic period, Reiter and Macphail 1979).
Forelimb/Hindlimb Grip Strength. An automated grip strength meter was used. Each animal was allowed to grip the proximal metal bar of the meter with its forepaws. The animal was pulled by the base of the tail until its grip was broken. The animal was drawn along the trough of the meter by the tail until its hind paws gripped the distal metal bar. A record of the force required to break the grip for each animal was made. Three consecutive trials were performed for each animal. The assessment was developed from the method employed by Meyer et al (1979).

Sensory Reactivity
Each animal was individually assessed for sensory reactivity to auditory, visual and proprioceptive stimuli. This assessment was developed from the methods employed by Irwin (1968) and Moser et al (1988). The scoring system used is outlined in The Key to Scoring System and Explanation for Behavioral Assessments and Sensory Reactivity Tests.
The following parameters were observed:
Grasp response
Touch escape
Vocalization
Pupil reflex
Toe pinch
Blink reflex
Tail pinch
Startle reflex
Finger approach

OTHER:
Oestrus cycling
Vaginal smears were taken daily for 21 days, on all test and control group females, during the final three weeks of the study. The stage of oestrus was recorded for each day.

Testosterone Hormone Assessment
On Day 90 of dosing, whole blood samples (ca. 0.35ml to yield approximately 0.15 ml of plasma) was taken from the lateral tail vein from all males into labelled lithium heparin coated blood tubes. All samples were mixed gently, by inverting several times, and placed on a roller before being centrifuged (approximately 2570 g, 10 minutes, room temperature). The plasma was separated off, collected into Eppendorf tubes and immediately placed on dry ice (within approximately 30 minutes of obtaining the blood sample). As soon as practical thereafter, plasma samples were stored in the freezer (approximately -70°C) before shipment, packed in dry ice, to the Test Site for analysis.

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Necropsy
On completion of the dosing period all animals were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination.
All animals were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.

Organ Weights
The following organs, removed from animals that were killed at the end of the study, were dissected free from fat and weighed before fixation:
Adrenals
Ovaries
Brain
Spleen
Right Epididymis
Right Testis
Heart
Thymus
Kidneys
Uterus
Liver

SPERM ANALYSIS
At necropsy, the left testis and epididymis were removed from all males, dissected from connective tissue and weighed separately.
For the epididymis, the distal region was incised and a sample of the luminal fluid was collected and transferred to a buffer solution for analysis of sperm motility. The semen sample was assessed using an automated semen analyser to determine the numbers of motile, progressively motile and non-motile sperm.
For the testis, the tunica albuginea was removed and the testicular tissue was stored frozen at approximately -20°C. The tissue was later thawed and homogenized in a suitable saline/detergent mixture. Samples of the homogenate were examined to determine the number of homogenization resistant spermatids present; see deviations from Study Plan.
The cauda epididymis was separated from the body of the epididymis and weighed. The cauda epididymis was frozen at approximately -20°C. The tissue was later thawed and homogenized in an appropriate saline/detergent to determine the numbers of homogenization resistant spermatids.
Morphological assessment was performed on a sample of a minimum of 200 sperm to determine the number with apparent structural anomalies.
Assessment of homogenization resistant spermatids and morphological evaluation were only performed for control and 1000 mg/kg bw/day males. As there were no treatment-related findings, these evaluations were not extended to males from other dose groups.

HISTOPATHOLOGY: Yes
Samples of the following tissues were removed from all animals and preserved in buffered 10%
formalin, except where stated:
Adrenals, Ovaries, Aorta (thoracic), Pancreas, Bone & bone marrow (femur including stifle joint), Pituitary, Bone & bone marrow (sternum), Prostate, Brain (including cerebrum, cerebellum and pons), Rectum, Caecum, Salivary glands (submaxillary), Colon, Sciatic nerve, Duodenum, Seminal vesicles, Right Epididymis, Skin, Esophagus, Spinal cord (cervical, mid-thoracic and lumbar), eyes, Gross lesions, Spleen, Heart, Stomach, Ileum (including Peyer’s patches), Right Testis, Jejunum Thymus, Kidneys Thyroid/Parathyroid, Liver, Tongue, Lungs (with bronchi), Trachea, Lymph nodes (mandibular and mesenteric), Urinary bladder, Mammary glands, Uterus (with cervix), Muscle (skeletal), Vagina.

All tissues were dispatched to the Test Site (Envigo CRS Limited) for processing (Principal Investigator: D Roberts). All tissues from control and 1000 mg/kg bw/day dose group animals were prepared as paraffin blocks, sectioned at a nominal thickness of 5 μm and stained with Hematoxylin and Eosin for subsequent microscopic examination. Any macroscopically observed lesions were also processed.
Microscopic examination was conducted by the Study Pathologist (W Henderson). A peer review of the findings was conducted by Peter Millar (Peter Millar Associates Ltd. Edinburgh) at the histopathology peer review test site.

Statistics:

Where considered appropriate, quantitative data was subjected to statistical analysis to detect the significance of intergroup differences from control; statistical significance was achieved at a level of p<0.05. Statistical analysis was performed on the following parameters: Grip Strength, Motor Activity, Body Weight Change, Hematology, Blood Chemistry, Absolute Organ Weights, Body Weight-Relative Organ Weights, Sperm Analysis Parameters,
Testosterone Concentrations.

Data were analyzed using the decision tree from the ProvantisTM Tables and Statistics Module as detailed as follows: Where appropriate, data transformations were performed using the most suitable method. The homogeneity of variance from mean values was analyzed using Bartlett’s test. Intergroup variances were assessed using suitable ANOVA, or if required, ANCOVA with appropriate covariates. Any transformed data were analyzed to find the lowest treatment level that showed a significant effect using the Williams Test for parametric data or the Shirley Test for nonparametric data. If no dose response was found but the data shows non-homogeneity of means, the data were analyzed by a stepwise Dunnett’s (parametric) or Steel (non-parametric) test to determine significant difference from the control group. Where the data were unsuitable for these analyses, pair-wise tests was performed using the Student t-test (parametric) or the Mann-
Whitney U test (non-parametric). Sperm analysis parameters and testosterone concentrations were statistically analyzed using the R Environment for Statistical Computing. Initially, the distribution of the data was assessed by the Shapiro-Wilk normality test, followed by assessment of the homogeneity of the data using Bartlett’s test. Where considered appropriate, parametric analysis of the data was applied incorporating analysis of variance (ANOVA), which if significant, was followed by pairwise comparisons using Dunnett’s test.

Clinical signs:

no effects observed

Description (incidence and severity):

Throughout the treatment period, there were no clinical signs at any dose level considered to be related to the toxicity of the test item.
Clinical observations were confined to a few instances of increased post-dose salivation for individual males treated with 1000 mg/kg bw/day during Weeks 5, 7 and 10 of dosing. A single incident of increased post-dose salivation was also observed for one female from this dose group during Week 10. Such observations are often observed following the oral gavage administration of an unpalatable or slightly irritant test item formulation and are considered to be of no toxicological importance.

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths during the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

When compared with controls, males treated with 1000 mg/kg bw/day showed statistically significantly lower group mean body weight gains during Weeks 6 and 13 of dosing (p<0.05). Females receiving 200 or 1000 mg/kg bw/day also showed statistically significantly reduced body weight gains during Weeks 10 and 13 (p<0.05 or p<0.01). Minor group mean body weight losses were observed for both sexes receiving 1000 mg/kg bw/day during Week 13. This resulted in marginally reduced overall group mean body weight gains for animals of either sex receiving 1000 mg/kg bw/day in relation to their respective controls (approximately 7% each).
The majority of individual body weight gain values for the test item-treated animals were, however, similar to controls and taking into consideration the small magnitude of these differences, this finding was deemed not to be of an adverse nature.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Compound intake was not exmained

Food efficiency:

not examined

Description (incidence and severity):

Throughout the treatment period, weekly food consumption values for the test item-treated males and females were generally comparable with their respective controls. Any differences in food conversion efficiency were deemed to be reflective of fluctuations in body weight gains and/or
dietary intake.

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

no effects observed

Description (incidence and severity):

Visual inspection of water bottles did not reveal any intergroup differences.
Compound intake was not exmained

Ophthalmological findings:

no effects observed

Description (incidence and severity):

Opthalmoscopic examination of animals of both sexes from the control and 1000 mg/kg bw/day dose groups did not indicate any treatment-related differences.

Haematological findings:

no effects observed

Description (incidence and severity):

HAEMATOLOGY
Males receiving the test item at all dose levels and females treated with 200 or 1000 mg/kg showed statistically significant decreases in mean corpuscular hemoglobin concentrations relative to controls (p<0.01 for females receiving 1000 mg/kg bw/day and p<0.05 in all other instances). There was no dose-relationship in males and whilst the majority of individual values from the test item-treated animals of either sex were within the historical control data ranges, 3/10 control males and 2/10 control females showed atypically high values which may explain these differences. Males treated with 200 or 1000 mg/kg bw/day also showed statistically significantly higher mean corpuscular volume in comparison with controls (p<0.05) albeit without any dose-dependence and with all individual values remaining within the background data ranges. In the absence of any alteration in related hematology parameters, these findings were considered to be of no toxicological significance. When compared with controls, group mean prothrombin times in females treated with 200 or 1000 mg/kg bw/day were statistically significantly higher than controls (p<0.05) in a dose related manner. Most individual values were within the background data ranges whilst the corresponding group mean values in males were similar to controls. In the absence of any related histopathology findings, this observation was considered to be of no toxicological relevance.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

At 1000 mg/kg bw/day, animals of either sex, in particular the females, showed statistically significantly higher plasma levels of urea when compared with controls (P<0.05). Group mean plasma concentration of creatinine in these females was also statistically significantly higher than controls (P<0.05), however males from this dose group showed comparable creatinine values to their respective controls. Females treated with 200 mg/kg bw/day also showed slightly higher plasma concentrations of urea and creatinine in relation to controls but without achieving statistical significance. Whilst these differences in females were dose-related and with most individual values for the 1000 mg/kg bw/day females outside the historical data ranges,
microscopic examination of relevant tissues did not identify any treatment-related findings and as such these observations were considered not to be of any toxicological importance. When compared with controls, males and females treated with 1000 mg/kg bw/day showed slightly higher plasma levels of glucose albeit without any dose-dependence and with statistical significance only achieved in females (p<0.01). Although most individual values for the 1000 mg/kg bw/day females were outside the historical control data ranges, in the absence of any histopathological correlates, this finding was considered to be of no toxicological significance. At all dose levels, females showed statistically significantly lower plasma levels of bilirubin with respect to controls (p<0.01). Whilst a dose-relationship was apparent, all individual values were within the control data ranges and group mean values in the corresponding males were similar to controls. Other statistically significant intergroup differences in relation to controls were confined to the 1000 mg/kg bw/day females and included a reduction in group mean plasma alkaline phosphatase level (p<0.05) and an increase in plasma chloride concentration (p<0.01). All individual values from the test item-treated females were within the background data ranges whilst the corresponding parameters in males from this dose group were similar to controls. As there were no treatment-related microscopic observations in any relevant tissues, these findings were deemed to be of no toxicological importance.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

Behavioral Assessments
There were no changes in the behavioral parameters considered to be related to treatment with Bismuth Subnitrate at any dose level.
Functional Performance Tests
There were no intergroup differences considered to be related to treatment with the test item. When compared with controls, males treated with 1000 mg/kg bw/day showed a statistically significant decrease in forelimb strength in 1/3 tests during Week 12 of the treatment period (p<0.05). Although a dose-relationship was apparent, similar intergroup differences were not evident in the remaining limb strength tests for these males or for any of the female dose groups and, in the absence of any signs of neurotoxicity on this study, this finding was considered likely to be incidental.
Sensory Reactivity Assessments
Sensory reactivity scores across all test item-treated dose groups were similar to controls.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

ORGAN WEIGHTS
Males treated with 200 or 1000 mg/kg bw/day showed statistically significantly lower absolute and body weight-related liver weights in relation to controls (p<0.05 and p<0.01, respectively).
A dose-relationship was evident, but most individual values from the test item-treated animals were within the historical control data ranges. In the absence of any histopathology correlates, this finding was considered unlikely to be of any toxicological significance.
Males treated with 40 mg/kg bw/day also showed statistically significantly higher thymus weights with respect to controls (p<0.05). The corresponding values from the remaining test item-treated male dose groups were similar to controls and as such this finding was considered to be incidental.

Gross pathological findings:

no effects observed

Description (incidence and severity):

At necropsy, most animals of either sex given 1000 mg/kg bw/day and 1/10 females treated with 200 mg/kg bw/day showed green colored contents in the caecum with one of the 1000 mg/kg bw/day females also showing green colored contents in the stomach. Microscopic evaluation of these tissues did not identify any treatment-related findings and as such these observations were considered unlikely to be of any toxicological significance.
A small number of males and females from all dose groups including controls showed red discoloration of lungs. One male from the 200 mg/kg bw/day dose group was observed with small/flaccid testes and small epididymides. These findings were deemed unlikely to be related to treatment with the test item.

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No consistent changes were noted which could be related to treatment with the test item. No histopathological changes were found to account for the clinical chemistry alterations nor were any associated with the caecal changes.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

Oestrus Cycling
There was no effect of treatment with Bismuth Subnitrate at any dose level on oestrus cycling activity in females as assessed over the last three weeks of dosing.
Testosterone Analysis
There was no effect of treatment with Bismuth Subnitrate at any dose level on plasma concentrations of testosterone in males.
Sperm Analysis
At necropsy, sperm analysis did not indicate any appreciable differences in group mean sperm concentration and motility at any dose level. An evaluation of homogenization resistant spermatids and morphology in males from the control and 1000 mg/kg bw/day dose groups also did not reveal any treatment-related differences.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No treatment-related adverse effects detected at highest dose tested (1000 mg/kg bw/day)

Key result

Critical effects observed:

no

Tables 1 to 17 are attached below under 'Attached Background Material'.

Conclusions:

The oral (gavage) administration of Bismuth Subnitrate to male and female Wistar Han™:RccHan™:WIST strain rats at dose levels up to 1000 mg/kg bw/day was well tolerated.
There was no adverse effect of treatment on body weight development and dietary intake in animals of either sex. Hematology, blood chemistry, testosterone hormone assessment, estrous cycle assessment in females, sperm analysis in males and microscopic examination of the selected tissues did not identify any findings of toxicological relevance. A dose level of 1000 mg/kg bw/day is therefore considered to be the ‘No Observed Adverse Effect Level’ (NOAEL).

Executive summary:

Introduction

The study was designed to investigate the systemic toxicity of the test item and is compatible with the following regulatory guidelines:

i) The OECD Guidelines for Testing of Chemicals No. 408 "Subchronic Oral Toxicity - Rodent: 90 Day Study” (Adopted 21 September 1998).

This study was also designed to be compatible with Commission Regulation (EC) No 440/2008 of 30 May 2008, laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).

Methods

The test item was administered by gavage to three groups, each of ten male and ten female Wistar Han™:RccHan™:WIST strain rats, for ninety consecutive days, at dose levels of 40, 200 and 1000 mg/kg bw/day. A control group of ten males and ten females was dosed with vehicle alone (Arachis oil BP).

Clinical signs, functional observations, body weight change, dietary intake and water consumption were monitored during the study. Hematology and blood chemistry were evaluated for all animals at the end of the study. Plasma concentrations of testosterone were evaluated for all males on Day 90 of dosing. Ophthalmoscopic examination was also performed on control group and high dose animals. In addition, sperm concentrations and motility were analyzed for males at necropsy followed by an evaluation of morphology and homogenization resistant spermatid counts in control and high dose males. Estrous cycling was also evaluated for females toward the end of the treatment period.

All animals were subjected to gross necropsy examination and histopathological evaluation of selected tissues from high dose and control animals was performed.

Results

Mortality

There were no unscheduled deaths during the study.

Clinical Observations

Throughout the treatment period, there were no clinical signs deemed to be indicative of test item toxicity.

Behavioral Assessment

Behavioral assessment scores across the test-item treated animals of either sex remained similar to the respective controls.

Functional Performance Tests

There were no treatment-related changes in functional performance at any dose level.

Sensory Reactivity Assessments

Sensory reactivity scores were comparable across all dose groups including controls.

Body Weight

There was no adverse effect of treatment with Bismuth Subnitrate at any dose level on body weight development in animal of either sex.

Food Consumption

There was no adverse effect of treatment with Bismuth Subnitrate at any dose level on food consumption or food conversion efficiency in animal of both sexes.

Water Consumption

Visual inspection of water bottles did not reveal any intergroup differences.

Ophthalmoscopy

Ophthalmoscopic examination of males and females from control and 1000 mg/kg bw/day dose group during Week 12 of the study did not reveal any treatment-related differences.

Estrous Cycling

There was no effect of treatment with the test item on estrous cycling activity assessed over the last three weeks of dosing in females.

Hematology

Hematology evaluations did not reveal any toxicologically significant effects in animals of either sex resulting from treatment with the test item.

Blood Chemistry

Blood chemistry evaluations did not indicate any effects of toxicological relevance in animals of both sexes resulting from test item administration.

Testosterone Hormone Assessment

There was no effect of treatment with the test item at any dose level on plasma levels of testosterone.

Necropsy

Changes noted in the colour of the caecal contents in a number of animals of either sex given 200 (one female) or 1000 mg/kg bw/day were not associated with any microscopic observations and as such this findings was considered to be no toxicological relevance. Any other macroscopic findings observed at necropsy were considered unlikely to be related to treatment with the test item.

Organ Weights

There were no intergroup differences considered to be of toxicological relevance.

Sperm Analysis

Analyses of sperm concentration, motility, morphology and homogenization resistant spermatids did not identify any treatment-related differences.

Histopathology

No findings were observed at histopathology which could be related to treatment with Bismuth Subnitrate within the confines of this study.

Conclusion

The oral (gavage) administration of Bismuth Subnitrate, to male and female Wistar Han™:RccHan™:WIST strain rats at dose levels up to 1000 mg/kg bw/day was well tolerated.

There was no adverse effect of treatment on body weight development and dietary intake in animals of either sex. Hematology, blood chemistry, testosterone hormone assessment, oestrus cycle assessment in females, sperm analysis in males and microscopic examination of the selected tissues did not identify any findings of toxicological relevance. A dose level of 1000 mg/kg bw/day is therefore considered to be the ‘No Observed Adverse Effect Level’ (NOAEL).

Reference 2

Endpoint:

sub-chronic toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included under 'Attached justification' in Section 13 and 'Cross-reference'.

Reason / purpose for cross-reference:

read-across source

Duration of treatment / exposure:

90 days

Frequency of treatment:

Once daily

Positive control:

None

Clinical signs:

no effects observed

Description (incidence and severity):

Throughout the treatment period, there were no clinical signs at any dose level considered to be related to the toxicity of the test item.
Clinical observations were confined to a few instances of increased post-dose salivation for individual males treated with 1000 mg/kg bw/day during Weeks 5, 7 and 10 of dosing. A single incident of increased post-dose salivation was also observed for one female from this dose group during Week 10. Such observations are often observed following the oral gavage administration of an unpalatable or slightly irritant test item formulation and are considered to be of no toxicological importance.

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths during the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

When compared with controls, males treated with 1000 mg/kg bw/day showed statistically significantly lower group mean body weight gains during Weeks 6 and 13 of dosing (p<0.05). Females receiving 200 or 1000 mg/kg bw/day also showed statistically significantly reduced body weight gains during Weeks 10 and 13 (p<0.05 or p<0.01). Minor group mean body weight losses were observed for both sexes receiving 1000 mg/kg bw/day during Week 13. This resulted in marginally reduced overall group mean body weight gains for animals of either sex receiving 1000 mg/kg bw/day in relation to their respective controls (approximately 7% each).
The majority of individual body weight gain values for the test item-treated animals were, however, similar to controls and taking into consideration the small magnitude of these differences, this finding was deemed not to be of an adverse nature.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Compound intake was not exmained

Food efficiency:

not examined

Description (incidence and severity):

Throughout the treatment period, weekly food consumption values for the test item-treated males and females were generally comparable with their respective controls. Any differences in food conversion efficiency were deemed to be reflective of fluctuations in body weight gains and/or
dietary intake.

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

no effects observed

Description (incidence and severity):

Visual inspection of water bottles did not reveal any intergroup differences.
Compound intake was not exmained

Ophthalmological findings:

no effects observed

Description (incidence and severity):

Opthalmoscopic examination of animals of both sexes from the control and 1000 mg/kg bw/day dose groups did not indicate any treatment-related differences.

Haematological findings:

no effects observed

Description (incidence and severity):

HAEMATOLOGY
Males receiving the test item at all dose levels and females treated with 200 or 1000 mg/kg showed statistically significant decreases in mean corpuscular hemoglobin concentrations relative to controls (p<0.01 for females receiving 1000 mg/kg bw/day and p<0.05 in all other instances). There was no dose-relationship in males and whilst the majority of individual values from the test item-treated animals of either sex were within the historical control data ranges, 3/10 control males and 2/10 control females showed atypically high values which may explain these differences. Males treated with 200 or 1000 mg/kg bw/day also showed statistically significantly higher mean corpuscular volume in comparison with controls (p<0.05) albeit without any dose-dependence and with all individual values remaining within the background data ranges. In the absence of any alteration in related hematology parameters, these findings were considered to be of no toxicological significance. When compared with controls, group mean prothrombin times in females treated with 200 or 1000 mg/kg bw/day were statistically significantly higher than controls (p<0.05) in a dose related manner. Most individual values were within the background data ranges whilst the corresponding group mean values in males were similar to controls. In the absence of any related histopathology findings, this observation was considered to be of no toxicological relevance.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

At 1000 mg/kg bw/day, animals of either sex, in particular the females, showed statistically significantly higher plasma levels of urea when compared with controls (P<0.05). Group mean plasma concentration of creatinine in these females was also statistically significantly higher than controls (P<0.05), however males from this dose group showed comparable creatinine values to their respective controls. Females treated with 200 mg/kg bw/day also showed slightly higher plasma concentrations of urea and creatinine in relation to controls but without achieving statistical significance. Whilst these differences in females were dose-related and with most individual values for the 1000 mg/kg bw/day females outside the historical data ranges,
microscopic examination of relevant tissues did not identify any treatment-related findings and as such these observations were considered not to be of any toxicological importance. When compared with controls, males and females treated with 1000 mg/kg bw/day showed slightly higher plasma levels of glucose albeit without any dose-dependence and with statistical significance only achieved in females (p<0.01). Although most individual values for the 1000 mg/kg bw/day females were outside the historical control data ranges, in the absence of any histopathological correlates, this finding was considered to be of no toxicological significance. At all dose levels, females showed statistically significantly lower plasma levels of bilirubin with respect to controls (p<0.01). Whilst a dose-relationship was apparent, all individual values were within the control data ranges and group mean values in the corresponding males were similar to controls. Other statistically significant intergroup differences in relation to controls were confined to the 1000 mg/kg bw/day females and included a reduction in group mean plasma alkaline phosphatase level (p<0.05) and an increase in plasma chloride concentration (p<0.01). All individual values from the test item-treated females were within the background data ranges whilst the corresponding parameters in males from this dose group were similar to controls. As there were no treatment-related microscopic observations in any relevant tissues, these findings were deemed to be of no toxicological importance.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Description (incidence and severity):

Behavioral Assessments
There were no changes in the behavioral parameters considered to be related to treatment with Bismuth Subnitrate at any dose level.
Functional Performance Tests
There were no intergroup differences considered to be related to treatment with the test item. When compared with controls, males treated with 1000 mg/kg bw/day showed a statistically significant decrease in forelimb strength in 1/3 tests during Week 12 of the treatment period (p<0.05). Although a dose-relationship was apparent, similar intergroup differences were not evident in the remaining limb strength tests for these males or for any of the female dose groups and, in the absence of any signs of neurotoxicity on this study, this finding was considered likely to be incidental.
Sensory Reactivity Assessments
Sensory reactivity scores across all test item-treated dose groups were similar to controls.

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

ORGAN WEIGHTS
Males treated with 200 or 1000 mg/kg bw/day showed statistically significantly lower absolute and body weight-related liver weights in relation to controls (p<0.05 and p<0.01, respectively).
A dose-relationship was evident, but most individual values from the test item-treated animals were within the historical control data ranges. In the absence of any histopathology correlates, this finding was considered unlikely to be of any toxicological significance.
Males treated with 40 mg/kg bw/day also showed statistically significantly higher thymus weights with respect to controls (p<0.05). The corresponding values from the remaining test item-treated male dose groups were similar to controls and as such this finding was considered to be incidental.

Gross pathological findings:

no effects observed

Description (incidence and severity):

At necropsy, most animals of either sex given 1000 mg/kg bw/day and 1/10 females treated with 200 mg/kg bw/day showed green colored contents in the caecum with one of the 1000 mg/kg bw/day females also showing green colored contents in the stomach. Microscopic evaluation of these tissues did not identify any treatment-related findings and as such these observations were considered unlikely to be of any toxicological significance.
A small number of males and females from all dose groups including controls showed red discoloration of lungs. One male from the 200 mg/kg bw/day dose group was observed with small/flaccid testes and small epididymides. These findings were deemed unlikely to be related to treatment with the test item.

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No consistent changes were noted which could be related to treatment with the test item. No histopathological changes were found to account for the clinical chemistry alterations nor were any associated with the caecal changes.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

Oestrus Cycling
There was no effect of treatment with Bismuth Subnitrate at any dose level on oestrus cycling activity in females as assessed over the last three weeks of dosing.
Testosterone Analysis
There was no effect of treatment with Bismuth Subnitrate at any dose level on plasma concentrations of testosterone in males.
Sperm Analysis
At necropsy, sperm analysis did not indicate any appreciable differences in group mean sperm concentration and motility at any dose level. An evaluation of homogenization resistant spermatids and morphology in males from the control and 1000 mg/kg bw/day dose groups also did not reveal any treatment-related differences.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

other: Read-across from an analogue

Sex:

male/female

Basis for effect level:

other: Read across from an analogue for which no treatment-related adverse effects detected at highest dose tested

Remarks on result:

other: Read-across from an analogue for which NOAEL = 1000 mg/kg bw/day

Key result

Critical effects observed:

no

Conclusions:

The oral (gavage) administration of Bismuth Subnitrate to male and female Wistar Han™:RccHan™:WIST strain rats at dose levels up to 1000 mg/kg bw/day was well tolerated.
There was no adverse effect of treatment on body weight development and dietary intake in animals of either sex. Hematology, blood chemistry, testosterone hormone assessment, estrous cycle assessment in females, sperm analysis in males and microscopic examination of the selected tissues did not identify any findings of toxicological relevance. A dose level of 1000 mg/kg bw/day is therefore considered to be the ‘No Observed Adverse Effect Level’ (NOAEL). Based on read across from the analogue bismuth subnitrate, the substance can be considered to have a NOAEL = 760.7 mg/kg bw/day.

Executive summary:

Introduction

The study was designed to investigate the systemic toxicity of the test item and is compatible with the following regulatory guidelines:

i) The OECD Guidelines for Testing of Chemicals No. 408 "Subchronic Oral Toxicity - Rodent: 90 Day Study” (Adopted 21 September 1998).

This study was also designed to be compatible with Commission Regulation (EC) No 440/2008 of 30 May 2008, laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).

 

Methods

The test item was administered by gavage to three groups, each of ten male and ten female Wistar Han™:RccHan™:WIST strain rats, for ninety consecutive days, at dose levels of 40, 200 and 1000 mg/kg bw/day. A control group of ten males and ten females was dosed with vehicle alone (Arachis oil BP).

Clinical signs, functional observations, body weight change, dietary intake and water consumption were monitored during the study. Hematology and blood chemistry were evaluated for all animals at the end of the study. Plasma concentrations of testosterone were evaluated for all males on Day 90 of dosing. Ophthalmoscopic examination was also performed on control group and high dose animals. In addition, sperm concentrations and motility were analyzed for males at necropsy followed by an evaluation of morphology and homogenization resistant spermatid counts in control and high dose males. Estrous cycling was also evaluated for females toward the end of the treatment period.

All animals were subjected to gross necropsy examination and histopathological evaluation of selected tissues from high dose and control animals was performed.

 

Results

Mortality

There were no unscheduled deaths during the study.

 

Clinical Observations

Throughout the treatment period, there were no clinical signs deemed to be indicative of test item toxicity.

 

Behavioral Assessment

Behavioral assessment scores across the test-item treated animals of either sex remained similar to the respective controls.

 

Functional Performance Tests

There were no treatment-related changes in functional performance at any dose level.

 

Sensory Reactivity Assessments

Sensory reactivity scores were comparable across all dose groups including controls.

 

Body Weight

There was no adverse effect of treatment with Bismuth Subnitrate at any dose level on body weight development in animal of either sex.

 

Food Consumption

There was no adverse effect of treatment with Bismuth Subnitrate at any dose level on food consumption or food conversion efficiency in animal of both sexes.

 

Water Consumption

Visual inspection of water bottles did not reveal any intergroup differences.

 

Ophthalmoscopy

Ophthalmoscopic examination of males and females from control and 1000 mg/kg bw/day dose group during Week 12 of the study did not reveal any treatment-related differences.

 

Estrous Cycling

There was no effect of treatment with the test item on estrous cycling activity assessed over the last three weeks of dosing in females.

 

Hematology

Hematology evaluations did not reveal any toxicologically significant effects in animals of either sex resulting from treatment with the test item.

 

Blood Chemistry

Blood chemistry evaluations did not indicate any effects of toxicological relevance in animals of both sexes resulting from test item administration.

 

Testosterone Hormone Assessment

There was no effect of treatment with the test item at any dose level on plasma levels of testosterone.

 

Necropsy

Changes noted in the colour of the caecal contents in a number of animals of either sex given 200 (one female) or 1000 mg/kg bw/day were not associated with any microscopic observations and as such this findings was considered to be no toxicological relevance. Any other macroscopic findings observed at necropsy were considered unlikely to be related to treatment with the test item.

 

Organ Weights

There were no intergroup differences considered to be of toxicological relevance.

 

Sperm Analysis

Analyses of sperm concentration, motility, morphology and homogenization resistant spermatids did not identify any treatment-related differences.

 

Histopathology

No findings were observed at histopathology which could be related to treatment with Bismuth Subnitrate within the confines of this study.

 

Conclusion

The oral (gavage) administration of Bismuth Subnitrate, to male and female Wistar Han™:RccHan™:WIST strain rats at dose levels up to 1000 mg/kg bw/day was well tolerated.

There was no adverse effect of treatment on body weight development and dietary intake in animals of either sex. Hematology, blood chemistry, testosterone hormone assessment, oestrus cycle assessment in females, sperm analysis in males and microscopic examination of the selected tissues did not identify any findings of toxicological relevance. A dose level of 1000 mg/kg bw/day is therefore considered to be the ‘No Observed Adverse Effect Level’ (NOAEL). Based on these results, the read-across approach was applied and the substance can be considered to have a NOAEL = 760.7 mg/kg bw/day.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

760.7 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

Regulatory toxicity study conducted to GLP

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included under 'Attached justification' in Section 13 and 'Cross-reference'.

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No abnormal clinical signs attributable to bismuth administration were observed in any treated group during the testing period. Loss of hair was observed in one and two animals in the 4 and 20 mg/kg groups, respectively.

Mortality:

mortality observed, treatment-related

Description (incidence):

Two animals of the control group, two animals of the 20 mg/kg group, one animal of the 4 mg/kg group, and one animal of the 0.8 mg/kg group died. A possible cause of death in these animals was excessive anaesthesia at administration or suffocation just after the administration associated with the intratracheal dose.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Suppression of body weight gain was observed at Day 29 and thereafter in the 20 mg/kg group, but it was not statistically significant.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No abnormal food consumption attributable to bismuth administration were observed in any treated group during the testing period.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A slight increase in erythrocyte count and MCHC were observed in the 20 mg/kg group, and slight increases in hemoglobin concentration and hematocrit value were observed in the 4 mg/kg and higher groups.
Higher rates of segmented neutrophil were observed in the 4 mg/kg and higher groups, and lower rates of lymphocytes were observed in the 0.8 mg/kg and higher groups.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

An increase in urea nitrogen was observed in the 20 mg/kg group. A decrease in ASAT in the 4 mg/kg group was observed, however, this was considered to be an incidental change, because it was not observed in the high dose group.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no significant differences between the control group and any treated group in the urinalysis.

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

The absolute and relative lung weights increased in the 0.8 mg/kg and higher groups. Increases in the relative brain and kidney weights were observed in the 20 mg/kg group, however, it was considered to be an incidental change related to decreased body weight, since suppression of body weight gain was also observed in the 20 mg/kg group and there was no difference in the absolute organ weight.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Pathological changes attributed to bismuth administration were observed in the lungs and bronchial lymph nodes. In the lungs, a brown patch was observed in 3, 4 and 8 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Black patches originating from the colour of bismuth and collapses were observed in all animals of the 4 and 20 mg/kg groups. Furthermore, enlargement of bronchial lymph nodes was observed in 6, 5 and 10 animals of the 0.8, 4 and 10 mg/kg groups, respectively. A brown patch in the lungs also observed in one animal in the control group, and slight focal inflammatory cell infiltration with small haemorrhage was observed in this lesion microscopically.A white patch in the liver was observed in 1, 2 and 3 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Although, it was not statistically significant, there was a dose dependent trend of increase in number of animals which had a white patch. This necropsy finding was possibly related to bismuth. As an incidental change, abnormal lobulation of the liver and cyst in the kidney were observed in one animal of the 0.8 mg/kg group. In the necropsy of 4 of 6 animals that died during the administration period, the following changes were observed in one animal of the 4 mg/kg group: dilatation and haemorrhage of the urinary bladder, possibly related to death, and other changes such as renal pelvic dilatation, ascites, small sized thymus and spleen, and black patch, dark red change and collapse of the lungs. The cause of death in this animal may have been anuria; it was considered to be an incidental mortality, since it occurred in only one animal.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathological changes attributed to bismuth were observed in the lungs, bronchial lymph nodes and kidneys. Focal inflammatory cell infiltration in the lungs was observed in all animals in the 0.8 mg/kg and higher groups. The incidence of lesions increased dose-dependently. In the lesions of inflammatory cell infiltration, hyperfrophy of alveolar epithelial cells was observed in the 0.8 mg/kg and higher groups, and hyperplasia of bronchial epithelial cells was observed in the 4 mg/kg and higher groups. Inflammatory cell infiltration in the 0.8 mg/kg and higher groups, hypertrophy of alveolar epithelium in the 4 mg/kg and higher groups, and hyperplasia of bronchial epithelial cell in the 20 mg/kg group showed statistically significant differences, as compared with the control group. Aggregation of foamy cells was observed in all groups including the control group and increased significantly in the 20 mg/kg group. Microscopic accumulation of bismuth was observed in all animals of the 4 and 20 mg/kg groups, and showed statistically significant differences as compared with the control group. In enlarged bronchial lymph nodes observed macroscopically, hyperplasia of the para-cortical area was observed, and increased pigment-laden phagocytic cells including the test substance was observed in 3 and 10 animals of the 4 and 20 mg/kg groups, respectively. In other changes, hyaline droplet of the proximal tubular epithelium in the kidney was observed in all groups including the control group, and its incidence decreased significantly in the 20 mg/kg group. The kidneys of representative animals of the control and 20 mg/kg groups were stained by PAS method, since a change in the glomerulus was suspected. In the result, there were no changes in the glomerulus and the hyaline droplets were PAS negative. Additional examination of the liver was conducted, since an effect of bismuth on the liver was suspected. Focal fatty degeneration of hepatic cells was observed in 1 and 2 animals of the 4 and 20 mg/kg groups, respectively. Brown pigment of the spleen was confirmed to be a hemosiderin pigment by Berlin blue staining.

Histopathological findings: neoplastic:

not specified

Details on results:

OTHER FINDINGS: The kinetics of bismuth can be described with a one-compartment pharmacokinetic model, since the logarithms of the lung concentrations of bismuth versus time plotted for each dosing group yield straight lines. From the slope of these lines, we calculated the half life of bismuth eliminationfrom the lungs as 4.47, 3.25, 2.10 days for the doses of 20, 100, 500 mg/kg, respectively.

Conclusions:

Dose-dependent foreign body inflammation of the lungs due to intratracheal administration of bismuth and physical change related to the pulmonary lesions were induced by intratracheal administration of bismuth once a week for 13 wk. Based on read across from the analogue bismuth, same conclusion can be taken for the target substance.

Executive summary:

Bismuth was administered at dose levels of 0, 0.8, 4, 20 mg/kg to male Crj:CD(SD)IGS rats (SPF) by intratracheal intermittent administration once a week for thirteen weeks to investigate its potential toxic effects; especially for specific adverse effects and changes related to pre-neoplastic lesions.

Dose-dependent foreign body inflammation of the lungs due to intratracheal administration of bismuth and physical change related to the pulmonary lesions were induced by intratracheal administration of bismuth once a week for 13 wk. Based on read across from the analogue bismuth, same conclusion can be taken for the target substance.

The study is well documented and was published in a peer review journal, however is not considered to be reliable (Klimisch 3) or sufficient for a key study, due to the novel route of administration. It could be used in a weight-of-evidence (WoE) approach for repeat dose toxicity.

 

 

Reference 2

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Route of exposure is not relevant for risk assessment.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Bismuth was administered at dose levels of 0, 0.8, 4, 20 mg/kg to male Crj:CD(SD)IGS rats (SPF) by intratracheal intermittent administration once a week for thirteen weeks to investigate its potential toxic effects; especially for specific adverse effects and changes related to pre-neoplastic lesions.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

particle size diameter: 1–2 μm

Species:

rat

Strain:

Crj: CD(SD)

Details on species / strain selection:

Male Crj:CD(SD)IGS rats (SPF) were used in the study.

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Rats were obtained from Charles River Japan, Inc.
- Age at study initiation: 6 weeks old
- Weight at study initiation: 197-229 g
- Diet: ad libitum; the animals were fed a pellet diet (MF, Oriental Yeast Co., Ltd.)
- Water: tap water ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 55 +/- 15
- Photoperiod: 12 hours dark/light cycle
- Ventilation frequency: about 12 changes per hour

Route of administration:

other: intratracheal instillation

Vehicle:

other: 0.5% carboxymethylcellulose sodium solution

Mass median aerodynamic diameter (MMAD):

other: No data

Remarks on MMAD:

MMAD not reported, Particle size diameter: 1-2 µm

Details on inhalation exposure:

Bismuth was weighed in to amounts of 0.032, 0.16 and 0.8 g and mixed with 20 mL of the vehicle for the dosing suspensions. The dose volume was set at 0.5 m//kg and the individual dose volume was calculated on the basis of the body weight measured just before administration on each administration day.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Considering the accumulation of bismuth in the lungs by repeated administration and its effects on the physical condition of the animals, it was decided that the dose interval should be once a week to keep a steady-state concentration of bismuth in the lungs, because in the single dose study, the bismuth concentration in the lungs decreased rapidly in each treatment group up to 8 days after administration, but thereafter it did not fluctuate largely.

Dose / conc.:

0 other: mg/kg

Remarks:

Control group

Dose / conc.:

0.8 other: mg/kg

Dose / conc.:

4 other: mg/kg

Dose / conc.:

20 other: mg/kg

No. of animals per sex per dose:

The dosing suspensions were administered to the twelve animals of each dosing group.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose selection rationale: The highest dose level was chosen as 20 mg/kg, since the result of a single dose toxicity study (Sano, 2005) showed that 20 mg/kg did not cause death.

Positive control:

No positive control substance was tested.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No data
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Clinical signs of the animals were observed twice a day (before and after administration) throughout the dosing period, and once a day in the morning during the other period.
BODY WEIGHT: Yes
- Time schedule for examinations: The body weights of all animals were measured once a week.
FOOD CONSUMPTION:- Time schedule for examinations: The gross weights of the feeders were measured once a week.
FOOD EFFICIENCY:- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION: No data
OPHTHALMOSCOPIC EXAMINATION: No data
HAEMATOLOGY: Yes
- Time schedule for collection of blood: On days of the scheduled necropsy, the animals were anesthetised; thereafter, blood samples were collected via the posterior vena cava.
- Anaesthetic used for blood collection: Yes (identity); intraperitoneal injection of sodium thiopental
- Parameters examined: For haematology, the erythrocyte count (RBC), haemoglobin concentration (Hb), haematocrit value (Ht), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), reticulocyte count, platelet count (PLT), prothrombin Time (PT), activated partial thromboplastin time (APTT), leukocyte count (WBC), and differential leukocyte count were measured.
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: On days of the scheduled necropsy, the animals were anesthetised; thereafter, blood samples were collected via the posterior vena cava.
- Parameters examined: For blood chemistry, the aspartatate aminotransferase (ASAT), alanine arninotransferase (AI-,aT), y-glutamyltrasferase (1GT), alkaline phosphatase (ALP), total bilirubin, blood urea nitrogen (BUN), creatinine, glucose, total cholesterol, triglycerides, total protein, albumin, A/G ratio, calcium, inorganic phosphorus, sodium (Na), potassium (K), and chlorine (Cl) were measured.
URINALYSIS: Yes
- Time schedule for collection of urine: Fresh urine samples from all the surviving animals were collected on the day before scheduled necropsy.
- Metabolism cages used for collection of urine: No data
- Parameters examined: pH, protein, glucose, ketone bodies, bilirubin, occult blood, and urobilinogen were measured.
NEUROBEHAVIOURAL EXAMINATION: No data

Sacrifice and pathology:

GROSS PATHOLOGY: Yes; After the blood sampling, all animals were sacrificed by exsanguinations via the abdominal aorta, and then subjected to necropsy. The following organs of all animals were weighed: brain, liver, kidney, spleen, and testis. Relative organ weights were calculated from body weights on each necropsy day.
HISTOPATHOLOGY: Yes; Histopathological examinations on the lung, liver, kidney, spleen, brain, and testis from the control and 20 mg/kg groups and gross lesions from all animals including the control group. The organs except for testes were fixed by 10% neutral phosphate-buffered formalin solution. The testes were fixed in Bouin's solution. The haematoxylin and eosin stained specimens were prepared according to the standard procedure and then microscopically examined. Furthermore, PAS stained specimens of the kidneys from three animals were prepared to confirm the change of the glomerulus. Berlin blue stained specimens of the spleen from three animals were prepared to confirm that the brown pigments found in the spleen were hemosiderin.

Other examinations:

No further examinations were made.

Statistics:

A multiple comparison test to analyse statistical significances in the numerical data (body weight, food consumption, haematology, blood chemistry,and organ weights) was used. If there was statistical significances in the data between groups, Dunnett's test or Dunnett type rank-sum test was conducted. Statistical significance in graded categorical data (urinalysis, necropsy findings and histopathological findings) was analyzed by a x b chi-square test. If statistically significant data were found, Cochran-Armitage trend test was conducted. Significance levels of 5% and 1% were chosen for all statistical analyses.

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No abnormal clinical signs attributable to bismuth administration were observed in any treated group during the testing period. Loss of hair was observed in one and two animals in the 4 and 20 mg/kg groups, respectively.

Mortality:

mortality observed, treatment-related

Description (incidence):

Two animals of the control group, two animals of the 20 mg/kg group, one animal of the 4 mg/kg group, and one animal of the 0.8 mg/kg group died. A possible cause of death in these animals was excessive anaesthesia at administration or suffocation just after the administration associated with the intratracheal dose.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Suppression of body weight gain was observed at Day 29 and thereafter in the 20 mg/kg group, but it was not statistically significant.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No abnormal food consumption attributable to bismuth administration were observed in any treated group during the testing period.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A slight increase in erythrocyte count and MCHC were observed in the 20 mg/kg group, and slight increases in hemoglobin concentration and hematocrit value were observed in the 4 mg/kg and higher groups.
Higher rates of segmented neutrophil were observed in the 4 mg/kg and higher groups, and lower rates of lymphocytes were observed in the 0.8 mg/kg and higher groups.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

An increase in urea nitrogen was observed in the 20 mg/kg group. A decrease in ASAT in the 4 mg/kg group was observed, however, this was considered to be an incidental change, because it was not observed in the high dose group.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no significant differences between the control group and any treated group in the urinalysis.

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

The absolute and relative lung weights increased in the 0.8 mg/kg and higher groups. Increases in the relative brain and kidney weights were observed in the 20 mg/kg group, however, it was considered to be an incidental change related to decreased body weight, since suppression of body weight gain was also observed in the 20 mg/kg group and there was no difference in the absolute organ weight.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Pathological changes attributed to bismuth administration were observed in the lungs and bronchial lymph nodes. In the lungs, a brown patch was observed in 3, 4 and 8 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Black patches originating from the colour of bismuth and collapses were observed in all animals of the 4 and 20 mg/kg groups. Furthermore, enlargement of bronchial lymph nodes was observed in 6, 5 and 10 animals of the 0.8, 4 and 10 mg/kg groups, respectively. A brown patch in the lungs also observed in one animal in the control group, and slight focal inflammatory cell infiltration with small haemorrhage was observed in this lesion microscopically.A white patch in the liver was observed in 1, 2 and 3 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Although, it was not statistically significant, there was a dose dependent trend of increase in number of animals which had a white patch. This necropsy finding was possibly related to bismuth. As an incidental change, abnormal lobulation of the liver and cyst in the kidney were observed in one animal of the 0.8 mg/kg group. In the necropsy of 4 of 6 animals that died during the administration period, the following changes were observed in one animal of the 4 mg/kg group: dilatation and haemorrhage of the urinary bladder, possibly related to death, and other changes such as renal pelvic dilatation, ascites, small sized thymus and spleen, and black patch, dark red change and collapse of the lungs. The cause of death in this animal may have been anuria; it was considered to be an incidental mortality, since it occurred in only one animal.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathological changes attributed to bismuth were observed in the lungs, bronchial lymph nodes and kidneys. Focal inflammatory cell infiltration in the lungs was observed in all animals in the 0.8 mg/kg and higher groups. The incidence of lesions increased dose-dependently. In the lesions of inflammatory cell infiltration, hyperfrophy of alveolar epithelial cells was observed in the 0.8 mg/kg and higher groups, and hyperplasia of bronchial epithelial cells was observed in the 4 mg/kg and higher groups. Inflammatory cell infiltration in the 0.8 mg/kg and higher groups, hypertrophy of alveolar epithelium in the 4 mg/kg and higher groups, and hyperplasia of bronchial epithelial cell in the 20 mg/kg group showed statistically significant differences, as compared with the control group. Aggregation of foamy cells was observed in all groups including the control group and increased significantly in the 20 mg/kg group. Microscopic accumulation of bismuth was observed in all animals of the 4 and 20 mg/kg groups, and showed statistically significant differences as compared with the control group. In enlarged bronchial lymph nodes observed macroscopically, hyperplasia of the para-cortical area was observed, and increased pigment-laden phagocytic cells including the test substance was observed in 3 and 10 animals of the 4 and 20 mg/kg groups, respectively. In other changes, hyaline droplet of the proximal tubular epithelium in the kidney was observed in all groups including the control group, and its incidence decreased significantly in the 20 mg/kg group. The kidneys of representative animals of the control and 20 mg/kg groups were stained by PAS method, since a change in the glomerulus was suspected. In the result, there were no changes in the glomerulus and the hyaline droplets were PAS negative. Additional examination of the liver was conducted, since an effect of bismuth on the liver was suspected. Focal fatty degeneration of hepatic cells was observed in 1 and 2 animals of the 4 and 20 mg/kg groups, respectively. Brown pigment of the spleen was confirmed to be a hemosiderin pigment by Berlin blue staining.

Histopathological findings: neoplastic:

not specified

Details on results:

OTHER FINDINGS: The kinetics of bismuth can be described with a one-compartment pharmacokinetic model, since the logarithms of the lung concentrations of bismuth versus time plotted for each dosing group yield straight lines. From the slope of these lines, we calculated the half life of bismuth eliminationfrom the lungs as 4.47, 3.25, 2.10 days for the doses of 20, 100, 500 mg/kg, respectively.

Conclusions:

Dose-dependent foreign body inflammation of the lungs due to intratracheal administration of bismuth and physical change related to the pulmonary lesions were induced by intratracheal administration of bismuth once a week for 13 wk.

Executive summary:

Bismuth was administered at dose levels of 0, 0.8, 4, 20 mg/kg to male Crj:CD(SD)IGS rats (SPF) by intratracheal intermittent administration once a week for thirteen weeks to investigate its potential toxic effects; especially for specific adverse effects and changes related to pre-neoplastic lesions.

The study is well documented and was published in a peer review journal, however is not considered to be reliable (Klimisch 3) or sufficient for a key study, due to the novel route of administration. It could be used in a weight-of-evidence (WoE) approach for repeat dose toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Study duration:

subchronic

Species:

rat

Quality of whole database:

The study was conducted via intratracheal dosing of the test substance suspension, therefore, the dose levels administered do not exactly reflect the inhalation exposure and are quoted in terms of mg/kg body weight. Dosing was undertaken on one occasion per week for 13 weeks since the potential for bismuth accumulation in the lung was a potential hazard. Consequently, the study has been assigned a Klimisch 3 (unreliable) assessment but is considered useful supporting information.

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Reference 1

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
Further information is included under 'Attached justification' in Section 13 and 'Cross-reference'.

Reason / purpose for cross-reference:

read-across source

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No abnormal clinical signs attributable to bismuth administration were observed in any treated group during the testing period. Loss of hair was observed in one and two animals in the 4 and 20 mg/kg groups, respectively.

Mortality:

mortality observed, treatment-related

Description (incidence):

Two animals of the control group, two animals of the 20 mg/kg group, one animal of the 4 mg/kg group, and one animal of the 0.8 mg/kg group died. A possible cause of death in these animals was excessive anaesthesia at administration or suffocation just after the administration associated with the intratracheal dose.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Suppression of body weight gain was observed at Day 29 and thereafter in the 20 mg/kg group, but it was not statistically significant.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No abnormal food consumption attributable to bismuth administration were observed in any treated group during the testing period.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A slight increase in erythrocyte count and MCHC were observed in the 20 mg/kg group, and slight increases in hemoglobin concentration and hematocrit value were observed in the 4 mg/kg and higher groups.
Higher rates of segmented neutrophil were observed in the 4 mg/kg and higher groups, and lower rates of lymphocytes were observed in the 0.8 mg/kg and higher groups.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

An increase in urea nitrogen was observed in the 20 mg/kg group. A decrease in ASAT in the 4 mg/kg group was observed, however, this was considered to be an incidental change, because it was not observed in the high dose group.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no significant differences between the control group and any treated group in the urinalysis.

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

The absolute and relative lung weights increased in the 0.8 mg/kg and higher groups. Increases in the relative brain and kidney weights were observed in the 20 mg/kg group, however, it was considered to be an incidental change related to decreased body weight, since suppression of body weight gain was also observed in the 20 mg/kg group and there was no difference in the absolute organ weight.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Pathological changes attributed to bismuth administration were observed in the lungs and bronchial lymph nodes. In the lungs, a brown patch was observed in 3, 4 and 8 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Black patches originating from the colour of bismuth and collapses were observed in all animals of the 4 and 20 mg/kg groups. Furthermore, enlargement of bronchial lymph nodes was observed in 6, 5 and 10 animals of the 0.8, 4 and 10 mg/kg groups, respectively. A brown patch in the lungs also observed in one animal in the control group, and slight focal inflammatory cell infiltration with small haemorrhage was observed in this lesion microscopically.A white patch in the liver was observed in 1, 2 and 3 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Although, it was not statistically significant, there was a dose dependent trend of increase in number of animals which had a white patch. This necropsy finding was possibly related to bismuth. As an incidental change, abnormal lobulation of the liver and cyst in the kidney were observed in one animal of the 0.8 mg/kg group. In the necropsy of 4 of 6 animals that died during the administration period, the following changes were observed in one animal of the 4 mg/kg group: dilatation and haemorrhage of the urinary bladder, possibly related to death, and other changes such as renal pelvic dilatation, ascites, small sized thymus and spleen, and black patch, dark red change and collapse of the lungs. The cause of death in this animal may have been anuria; it was considered to be an incidental mortality, since it occurred in only one animal.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathological changes attributed to bismuth were observed in the lungs, bronchial lymph nodes and kidneys. Focal inflammatory cell infiltration in the lungs was observed in all animals in the 0.8 mg/kg and higher groups. The incidence of lesions increased dose-dependently. In the lesions of inflammatory cell infiltration, hyperfrophy of alveolar epithelial cells was observed in the 0.8 mg/kg and higher groups, and hyperplasia of bronchial epithelial cells was observed in the 4 mg/kg and higher groups. Inflammatory cell infiltration in the 0.8 mg/kg and higher groups, hypertrophy of alveolar epithelium in the 4 mg/kg and higher groups, and hyperplasia of bronchial epithelial cell in the 20 mg/kg group showed statistically significant differences, as compared with the control group. Aggregation of foamy cells was observed in all groups including the control group and increased significantly in the 20 mg/kg group. Microscopic accumulation of bismuth was observed in all animals of the 4 and 20 mg/kg groups, and showed statistically significant differences as compared with the control group. In enlarged bronchial lymph nodes observed macroscopically, hyperplasia of the para-cortical area was observed, and increased pigment-laden phagocytic cells including the test substance was observed in 3 and 10 animals of the 4 and 20 mg/kg groups, respectively. In other changes, hyaline droplet of the proximal tubular epithelium in the kidney was observed in all groups including the control group, and its incidence decreased significantly in the 20 mg/kg group. The kidneys of representative animals of the control and 20 mg/kg groups were stained by PAS method, since a change in the glomerulus was suspected. In the result, there were no changes in the glomerulus and the hyaline droplets were PAS negative. Additional examination of the liver was conducted, since an effect of bismuth on the liver was suspected. Focal fatty degeneration of hepatic cells was observed in 1 and 2 animals of the 4 and 20 mg/kg groups, respectively. Brown pigment of the spleen was confirmed to be a hemosiderin pigment by Berlin blue staining.

Histopathological findings: neoplastic:

not specified

Details on results:

OTHER FINDINGS: The kinetics of bismuth can be described with a one-compartment pharmacokinetic model, since the logarithms of the lung concentrations of bismuth versus time plotted for each dosing group yield straight lines. From the slope of these lines, we calculated the half life of bismuth eliminationfrom the lungs as 4.47, 3.25, 2.10 days for the doses of 20, 100, 500 mg/kg, respectively.

Conclusions:

Dose-dependent foreign body inflammation of the lungs due to intratracheal administration of bismuth and physical change related to the pulmonary lesions were induced by intratracheal administration of bismuth once a week for 13 wk. Based on read across from the analogue bismuth, same conclusion can be taken for the target substance.

Executive summary:

Bismuth was administered at dose levels of 0, 0.8, 4, 20 mg/kg to male Crj:CD(SD)IGS rats (SPF) by intratracheal intermittent administration once a week for thirteen weeks to investigate its potential toxic effects; especially for specific adverse effects and changes related to pre-neoplastic lesions.

Dose-dependent foreign body inflammation of the lungs due to intratracheal administration of bismuth and physical change related to the pulmonary lesions were induced by intratracheal administration of bismuth once a week for 13 wk. Based on read across from the analogue bismuth, same conclusion can be taken for the target substance.

The study is well documented and was published in a peer review journal, however is not considered to be reliable (Klimisch 3) or sufficient for a key study, due to the novel route of administration. It could be used in a weight-of-evidence (WoE) approach for repeat dose toxicity.

 

 

Reference 2

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Route of exposure is not relevant for risk assessment.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Bismuth was administered at dose levels of 0, 0.8, 4, 20 mg/kg to male Crj:CD(SD)IGS rats (SPF) by intratracheal intermittent administration once a week for thirteen weeks to investigate its potential toxic effects; especially for specific adverse effects and changes related to pre-neoplastic lesions.

GLP compliance:

no

Limit test:

no

Specific details on test material used for the study:

particle size diameter: 1–2 μm

Species:

rat

Strain:

Crj: CD(SD)

Details on species / strain selection:

Male Crj:CD(SD)IGS rats (SPF) were used in the study.

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Rats were obtained from Charles River Japan, Inc.
- Age at study initiation: 6 weeks old
- Weight at study initiation: 197-229 g
- Diet: ad libitum; the animals were fed a pellet diet (MF, Oriental Yeast Co., Ltd.)
- Water: tap water ad libitum
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 55 +/- 15
- Photoperiod: 12 hours dark/light cycle
- Ventilation frequency: about 12 changes per hour

Route of administration:

other: intratracheal instillation

Vehicle:

other: 0.5% carboxymethylcellulose sodium solution

Mass median aerodynamic diameter (MMAD):

other: No data

Remarks on MMAD:

MMAD not reported, Particle size diameter: 1-2 µm

Details on inhalation exposure:

Bismuth was weighed in to amounts of 0.032, 0.16 and 0.8 g and mixed with 20 mL of the vehicle for the dosing suspensions. The dose volume was set at 0.5 m//kg and the individual dose volume was calculated on the basis of the body weight measured just before administration on each administration day.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

Considering the accumulation of bismuth in the lungs by repeated administration and its effects on the physical condition of the animals, it was decided that the dose interval should be once a week to keep a steady-state concentration of bismuth in the lungs, because in the single dose study, the bismuth concentration in the lungs decreased rapidly in each treatment group up to 8 days after administration, but thereafter it did not fluctuate largely.

Dose / conc.:

0 other: mg/kg

Remarks:

Control group

Dose / conc.:

0.8 other: mg/kg

Dose / conc.:

4 other: mg/kg

Dose / conc.:

20 other: mg/kg

No. of animals per sex per dose:

The dosing suspensions were administered to the twelve animals of each dosing group.

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose selection rationale: The highest dose level was chosen as 20 mg/kg, since the result of a single dose toxicity study (Sano, 2005) showed that 20 mg/kg did not cause death.

Positive control:

No positive control substance was tested.

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: No data
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Clinical signs of the animals were observed twice a day (before and after administration) throughout the dosing period, and once a day in the morning during the other period.
BODY WEIGHT: Yes
- Time schedule for examinations: The body weights of all animals were measured once a week.
FOOD CONSUMPTION:- Time schedule for examinations: The gross weights of the feeders were measured once a week.
FOOD EFFICIENCY:- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data
WATER CONSUMPTION: No data
OPHTHALMOSCOPIC EXAMINATION: No data
HAEMATOLOGY: Yes
- Time schedule for collection of blood: On days of the scheduled necropsy, the animals were anesthetised; thereafter, blood samples were collected via the posterior vena cava.
- Anaesthetic used for blood collection: Yes (identity); intraperitoneal injection of sodium thiopental
- Parameters examined: For haematology, the erythrocyte count (RBC), haemoglobin concentration (Hb), haematocrit value (Ht), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), reticulocyte count, platelet count (PLT), prothrombin Time (PT), activated partial thromboplastin time (APTT), leukocyte count (WBC), and differential leukocyte count were measured.
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: On days of the scheduled necropsy, the animals were anesthetised; thereafter, blood samples were collected via the posterior vena cava.
- Parameters examined: For blood chemistry, the aspartatate aminotransferase (ASAT), alanine arninotransferase (AI-,aT), y-glutamyltrasferase (1GT), alkaline phosphatase (ALP), total bilirubin, blood urea nitrogen (BUN), creatinine, glucose, total cholesterol, triglycerides, total protein, albumin, A/G ratio, calcium, inorganic phosphorus, sodium (Na), potassium (K), and chlorine (Cl) were measured.
URINALYSIS: Yes
- Time schedule for collection of urine: Fresh urine samples from all the surviving animals were collected on the day before scheduled necropsy.
- Metabolism cages used for collection of urine: No data
- Parameters examined: pH, protein, glucose, ketone bodies, bilirubin, occult blood, and urobilinogen were measured.
NEUROBEHAVIOURAL EXAMINATION: No data

Sacrifice and pathology:

GROSS PATHOLOGY: Yes; After the blood sampling, all animals were sacrificed by exsanguinations via the abdominal aorta, and then subjected to necropsy. The following organs of all animals were weighed: brain, liver, kidney, spleen, and testis. Relative organ weights were calculated from body weights on each necropsy day.
HISTOPATHOLOGY: Yes; Histopathological examinations on the lung, liver, kidney, spleen, brain, and testis from the control and 20 mg/kg groups and gross lesions from all animals including the control group. The organs except for testes were fixed by 10% neutral phosphate-buffered formalin solution. The testes were fixed in Bouin's solution. The haematoxylin and eosin stained specimens were prepared according to the standard procedure and then microscopically examined. Furthermore, PAS stained specimens of the kidneys from three animals were prepared to confirm the change of the glomerulus. Berlin blue stained specimens of the spleen from three animals were prepared to confirm that the brown pigments found in the spleen were hemosiderin.

Other examinations:

No further examinations were made.

Statistics:

A multiple comparison test to analyse statistical significances in the numerical data (body weight, food consumption, haematology, blood chemistry,and organ weights) was used. If there was statistical significances in the data between groups, Dunnett's test or Dunnett type rank-sum test was conducted. Statistical significance in graded categorical data (urinalysis, necropsy findings and histopathological findings) was analyzed by a x b chi-square test. If statistically significant data were found, Cochran-Armitage trend test was conducted. Significance levels of 5% and 1% were chosen for all statistical analyses.

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

No abnormal clinical signs attributable to bismuth administration were observed in any treated group during the testing period. Loss of hair was observed in one and two animals in the 4 and 20 mg/kg groups, respectively.

Mortality:

mortality observed, treatment-related

Description (incidence):

Two animals of the control group, two animals of the 20 mg/kg group, one animal of the 4 mg/kg group, and one animal of the 0.8 mg/kg group died. A possible cause of death in these animals was excessive anaesthesia at administration or suffocation just after the administration associated with the intratracheal dose.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Suppression of body weight gain was observed at Day 29 and thereafter in the 20 mg/kg group, but it was not statistically significant.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

No abnormal food consumption attributable to bismuth administration were observed in any treated group during the testing period.

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

effects observed, treatment-related

Description (incidence and severity):

A slight increase in erythrocyte count and MCHC were observed in the 20 mg/kg group, and slight increases in hemoglobin concentration and hematocrit value were observed in the 4 mg/kg and higher groups.
Higher rates of segmented neutrophil were observed in the 4 mg/kg and higher groups, and lower rates of lymphocytes were observed in the 0.8 mg/kg and higher groups.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

An increase in urea nitrogen was observed in the 20 mg/kg group. A decrease in ASAT in the 4 mg/kg group was observed, however, this was considered to be an incidental change, because it was not observed in the high dose group.

Urinalysis findings:

no effects observed

Description (incidence and severity):

There were no significant differences between the control group and any treated group in the urinalysis.

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

The absolute and relative lung weights increased in the 0.8 mg/kg and higher groups. Increases in the relative brain and kidney weights were observed in the 20 mg/kg group, however, it was considered to be an incidental change related to decreased body weight, since suppression of body weight gain was also observed in the 20 mg/kg group and there was no difference in the absolute organ weight.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

Pathological changes attributed to bismuth administration were observed in the lungs and bronchial lymph nodes. In the lungs, a brown patch was observed in 3, 4 and 8 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Black patches originating from the colour of bismuth and collapses were observed in all animals of the 4 and 20 mg/kg groups. Furthermore, enlargement of bronchial lymph nodes was observed in 6, 5 and 10 animals of the 0.8, 4 and 10 mg/kg groups, respectively. A brown patch in the lungs also observed in one animal in the control group, and slight focal inflammatory cell infiltration with small haemorrhage was observed in this lesion microscopically.A white patch in the liver was observed in 1, 2 and 3 animals of the 0.8, 4 and 20 mg/kg groups, respectively. Although, it was not statistically significant, there was a dose dependent trend of increase in number of animals which had a white patch. This necropsy finding was possibly related to bismuth. As an incidental change, abnormal lobulation of the liver and cyst in the kidney were observed in one animal of the 0.8 mg/kg group. In the necropsy of 4 of 6 animals that died during the administration period, the following changes were observed in one animal of the 4 mg/kg group: dilatation and haemorrhage of the urinary bladder, possibly related to death, and other changes such as renal pelvic dilatation, ascites, small sized thymus and spleen, and black patch, dark red change and collapse of the lungs. The cause of death in this animal may have been anuria; it was considered to be an incidental mortality, since it occurred in only one animal.

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Histopathological changes attributed to bismuth were observed in the lungs, bronchial lymph nodes and kidneys. Focal inflammatory cell infiltration in the lungs was observed in all animals in the 0.8 mg/kg and higher groups. The incidence of lesions increased dose-dependently. In the lesions of inflammatory cell infiltration, hyperfrophy of alveolar epithelial cells was observed in the 0.8 mg/kg and higher groups, and hyperplasia of bronchial epithelial cells was observed in the 4 mg/kg and higher groups. Inflammatory cell infiltration in the 0.8 mg/kg and higher groups, hypertrophy of alveolar epithelium in the 4 mg/kg and higher groups, and hyperplasia of bronchial epithelial cell in the 20 mg/kg group showed statistically significant differences, as compared with the control group. Aggregation of foamy cells was observed in all groups including the control group and increased significantly in the 20 mg/kg group. Microscopic accumulation of bismuth was observed in all animals of the 4 and 20 mg/kg groups, and showed statistically significant differences as compared with the control group. In enlarged bronchial lymph nodes observed macroscopically, hyperplasia of the para-cortical area was observed, and increased pigment-laden phagocytic cells including the test substance was observed in 3 and 10 animals of the 4 and 20 mg/kg groups, respectively. In other changes, hyaline droplet of the proximal tubular epithelium in the kidney was observed in all groups including the control group, and its incidence decreased significantly in the 20 mg/kg group. The kidneys of representative animals of the control and 20 mg/kg groups were stained by PAS method, since a change in the glomerulus was suspected. In the result, there were no changes in the glomerulus and the hyaline droplets were PAS negative. Additional examination of the liver was conducted, since an effect of bismuth on the liver was suspected. Focal fatty degeneration of hepatic cells was observed in 1 and 2 animals of the 4 and 20 mg/kg groups, respectively. Brown pigment of the spleen was confirmed to be a hemosiderin pigment by Berlin blue staining.

Histopathological findings: neoplastic:

not specified

Details on results:

OTHER FINDINGS: The kinetics of bismuth can be described with a one-compartment pharmacokinetic model, since the logarithms of the lung concentrations of bismuth versus time plotted for each dosing group yield straight lines. From the slope of these lines, we calculated the half life of bismuth eliminationfrom the lungs as 4.47, 3.25, 2.10 days for the doses of 20, 100, 500 mg/kg, respectively.

Conclusions:

Dose-dependent foreign body inflammation of the lungs due to intratracheal administration of bismuth and physical change related to the pulmonary lesions were induced by intratracheal administration of bismuth once a week for 13 wk.

Executive summary:

Bismuth was administered at dose levels of 0, 0.8, 4, 20 mg/kg to male Crj:CD(SD)IGS rats (SPF) by intratracheal intermittent administration once a week for thirteen weeks to investigate its potential toxic effects; especially for specific adverse effects and changes related to pre-neoplastic lesions.

The study is well documented and was published in a peer review journal, however is not considered to be reliable (Klimisch 3) or sufficient for a key study, due to the novel route of administration. It could be used in a weight-of-evidence (WoE) approach for repeat dose toxicity.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Study duration:

subchronic

Species:

rat

Quality of whole database:

The study was conducted via intratracheal dosing of the test substance suspension, therefore, the dose levels administered do not exactly reflect the inhalation exposure and are quoted in terms of mg/kg body weight. Dosing was undertaken on one occasion per week for 13 weeks since the potential for bismuth accumulation in the lung was a potential hazard. Consequently, the study has been assigned a Klimisch 3 (unreliable) assessment but is considered useful supporting information.

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Bismuth subnitrate was evaluated for toxicity by daily oral gavage to rats over 90 days at dose levels up to 1000 mg/kg/day. There was no adverse effect of treatment on body weight or food intake in animals of either sex. Haematology, blood chemistry, testosterone hormone assessment, oestrous cycle assessment in females, sperm analysis in males and microscopic examination of the selected tissues did not identify any findings of toxicological relevance and the high dose level of 1000 mg/kg bw/day was therefore considered to be the ‘No Observed Adverse Effect Level’ (NOAEL).

In addition, a supporting oral toxicity study in rats over 28-days at dose levels up to 1000 mg/kg/day was conducted with bismuth alone. The NOAEL in this study was also determined to be 1000 mg/kg/day. Similarly a 90-day inhalatory toxicity study in rats was conducted via intermittent (once per week) intratracheal administration of bismuth at dose levels of 0.8, 4 and 20 mg/kg in which there were no indications of systemic toxicity at dose levels which caused dose-dependent foreign-body inflammation of the lungs due to intratracheal administration and physical change related to the pulmonary lesions. This latter study is considered not sufficiently reliable for a key study due to the novel route and frequency of administration but is used in the weight of evidence assessment.

Justification for classification or non-classification

There were no signs of systemic toxicity in the key 90-day oral toxicity study in rats with bismuth subnitrate or in the supporting 28-day oral rat study and the 90-day intratracheal rat study. Consequently, there was no evidence to support a classification for target organ toxicity via these routes of administration. With the NOAEL for oral administration outside the guidance value range for classification via the oral route, it can be concluded that, according to the Globally Harmonised Classification System (GHS) and EU CLP criteria, the test item does not require classification for repeat dose toxicity.