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Administrative data

Description of key information

The oral administration of Strontium Titanium Trioxide to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, resulted in treatment-related changes at 1000 mg/kg bw/day. The effects detected were considered not to represent an adverse effect, therefore the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was considered to be 1000 mg/kg bw/day.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records
Reference
Endpoint:
short-term repeated dose toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
09 July 2012 and 20 February 2013
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficincies, which do not affect the quality of relevant results.
Reason / purpose for cross-reference:
reference to other study
Qualifier:
according to guideline
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Deviations:
yes
Remarks:
Please see "Principles of Method" for details.
Principles of method if other than guideline:
On a number of occasions during the acclimatisation and treatment phases of the study, the humidity was outside of the ranges specified in the study plan. Values were never more than 10% outside of the values stated.
This deviation to the study plan was considered not to affect the purpose or integrity of the study.
GLP compliance:
yes (incl. QA statement)
Limit test:
no
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
A sufficient number of male and female Wistar Han™:RccHan™:WIST strain rats were obtained from Harlan Laboratories U.K. Ltd., Blackthorn, Bicester, Oxon, UK. On receipt the animals were examined for signs of ill-health or injury. The animals were acclimatised for seven days during which time their health status was assessed. A total of eighty animals (forty males and forty females) were accepted into the study. At the start of treatment the males weighed 303 to 344g, the females weighed 189 to 221g, and were approximately twelve weeks old.
Initially, all animals were housed in groups of five in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding (Datesand Ltd., Cheshire, UK). During the pairing phase, animals were transferred to polypropylene grid floor cages suspended over trays lined with absorbent paper on a one male: one female basis within each dose group. Following evidence of successful mating, the males were returned to their original cages. Mated females were housed individually during gestation and lactation, in solid floor polypropylene cages with stainless steel mesh lids and softwood flakes.
The animals were allowed free access to food and water. A pelleted diet (Rodent 2018C Teklad Global Certified Diet, Harlan Laboratories U.K. Ltd., Oxon, UK) was used. Mains drinking water was supplied from polycarbonate bottles attached to the cage. The diet and drinking water were considered not to contain any contaminant at a level that might have affected the purpose or integrity of the study. Environmental enrichment was provided in the form of wooden chew blocks and cardboard fun tunnels (Datesand Ltd., Cheshire, UK) except for paired animals and mated females during gestation and lactation.
The animals were housed in a single air-conditioned room within the Harlan Laboratories Ltd., Shardlow, UK, Barrier Maintained Rodent Facility. The rate of air exchange was at least fifteen air changes per hour and the low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness. Environmental conditions were continuously monitored by a computerised system. The temperatures and relative humidity controls were set to achieve target values of 21 ± 2°C and 55 ± 15% respectively. Short term deviations from these targets were considered not to affect the purpose or integrity of the study.
The animals were allocated to dose groups using a randomisation procedure based on stratified body weights and the group mean body weights were then determined to ensure similarity between the dose groups. The animals were uniquely identified within the study, by an ear punching system routinely used in these laboratories.

IN-LIFE DATES: The in-life phase of the study was conducted between 11 July 2012 (first day of treatment) and 02 September 2012 (final necropsy).
Route of administration:
oral: gavage
Vehicle:
arachis oil
Details on oral exposure:
For the purpose of this study the test item was prepared at the appropriate concentrations as a solution in Arachis oil BP. The homogeneity of the test item formulations was determined by Harlan Laboratories Ltd., Shardlow, UK, Analytical Services. Due to the complex nature of the test item, stability was not determined.
Formulations were prepared weekly and stored at approximately +4ºC in the dark.
Animals were allocated to treatment groups as seen in the table "Treatment Groups" in "any other information on materials and methods" below. The volume of test and control item administered to each animal was based on the most recent scheduled body weight and was adjusted at regular intervals.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The homogeneity of the test item formulations was determined by Harlan Laboratories Ltd., Shardlow, UK, Analytical Services. Due to the complex nature of the test item, stability was not determined. Formulations were prepared weekly and stored at approximately +4ºC in the dark (see Appendix 24 for details of Chemical Analysis).
Samples of each test item formulation were taken and analysed for concentration of Strontium Titanium Trioxide at Harlan Laboratories Ltd., Shardlow, UK, Analytical Services. The results indicate that the prepared formulations were within ± 10% of the nominal concentration.
Duration of treatment / exposure:
The test item was administered by gavage to three groups, each of ten male and ten female Wistar Han™:RccHan™:WIST strain rats, for up to eight weeks (including a two week pre-pairing phase, pairing, gestation and early lactation for females).
Frequency of treatment:
Daily administration.
Remarks:
Doses / Concentrations:
100 mg/kg bw/day
Basis:
actual ingested
Remarks:
Doses / Concentrations:
300 mg/kg bw/day
Basis:
actual ingested
Remarks:
Doses / Concentrations:
1000 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
Ten animals per sex per dose.
Control animals:
yes, concurrent vehicle
Details on study design:
Procedure
Chronological Sequence of Study
i) Groups of ten male and ten female animals were treated daily at the appropriate dose level throughout the study (except for females during parturition where
applicable). The first day of dosing was designated as Day 1 of the study.
ii) Prior to the start of treatment and once weekly thereafter, all animals were observed for signs of functional/behavioural toxicity.
iii) On Day 15, animals were paired on a 1 male: 1 female basis within each dose group for a maximum of fourteen days.
iv) Following evidence of mating (designated as Day 0 post coitum) the males were returned to their original cages and females were transferred to individual cages.
v) On completion of the pre-pairing phase (during Week 6), five selected males per dose group were evaluated for functional/sensory responses to various stimuli.
vi) Pregnant females were allowed to give birth and maintain their offspring until Day 5 post partum. Litter size, offspring weight and sex, surface righting and clinical signs were also recorded during this period.
vii) At Day 4 post partum, five selected females per dose group were evaluated for functional/sensory responses to various stimuli.
viii) Blood samples were taken from five males from each dose group for haematological and blood chemical assessments on Day 42. The male dose
groups were killed and examined macroscopically on Day 43.
ix) Blood samples were taken from five randomly selected females from each dose group for haematological and blood chemical assessment on Day 4 post partum. At Day 5 post partum, all females and offspring were killed and examined macroscopically. Any female which did not produce a pregnancy was also killed and examined macroscopically.
Observations and examinations performed and frequency:
DETAILED CLINICAL OBSERVATIONS:
All animals were examined for overt signs of toxicity, ill-health and behavioural change immediately before dosing, up to thirty minutes after dosing, and one and five hours after dosing, during the working week. Animals were observed immediately before dosing, soon after dosing, and one hour after dosing at weekends and public holidays (except for females during parturition where applicable). All observations were recorded.

BODY WEIGHT:
Individual body weights were recorded on Day 1 (prior to dosing) and then weekly for males until termination and weekly for females until mating was evident. Body weights were then recorded for females on Days 0, 7, 14 and 20 post coitum, and on Days 1 and 4 post partum.

FOOD CONSUMPTION
During the pre-pairing period, weekly food consumption was recorded for each cage of adults. This was continued for males after the mating phase. For females showing evidence of mating, food consumption was recorded for the periods covering post coitum Days 0-7, 7-14 and 14-20. For females with live litters, food consumption was recorded on Days 1 and 4 post partum.

FOOD EFFICIENCY:
Food efficiency (the ratio of body weight change/dietary intake) was calculated retrospectively for males throughout the study period (with the exception of the mating phase) and for females during the pre-pairing phase. Due to offspring growth and milk production, food efficiency could not be accurately calculated for females during gestation and lactation.

WATER CONSUMPTION
Water intake was observed daily by visual inspection of water bottles for any overt changes.

Laboratory Investigations
Haematological and blood chemical investigations were performed on five males and five females selected from each test and control group prior to termination (Day 42 for males and Day 4 post partum for females). Blood samples were obtained from the lateral tail vein. Where necessary repeat samples were taken by cardiac puncture at termination. Animals were not fasted prior to sampling.
HAEMATOLOGY:
The following parameters were measured on blood collected into tubes containing potassium EDTA anti-coagulant:
Haemoglobin (Hb)
Erythrocyte count (RBC)
Haematocrit (Hct)
Erythrocyte indices - mean corpuscular haemoglobin (MCH)
- mean corpuscular volume (MCV)
- mean corpuscular haemoglobin concentration (MCHC)
Total leucocyte count (WBC)
Differential leucocyte 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:
The following parameters were measured on plasma from blood collected into tubes containing lithium heparin anti-coagulant:
Urea Calcium (Ca++), Glucose Inorganic phosphorus (P), Total protein (Tot.Prot.), Aspartate aminotransferase (ASAT), Albumin Alanine aminotransferase (ALAT), Albumin/Globulin (A/G) ratio (by calculation), Alkaline phosphatase (AP), Sodium (Na+), Creatinine (Creat), Potassium (K+), Total cholesterol (Chol), Chloride (Cl-), Total bilirubin (Bili), Bile acids.

FUNCTIONAL OBSERVATIONS
Prior to the start of treatment and at weekly intervals thereafter, all animals were observed for signs of functional/behavioural toxicity. Functional performance tests were also performed on five selected males and females from each dose level, prior to termination, together with an assessment of sensory reactivity to various stimuli.
NEUROBEHAVIOURAL EXAMINATION:
Behavioural Assessments
Detailed individual clinical observations were performed for each animal using a purpose built arena. The following parameters were observed:
Gait, Hyper/Hypothermia, Tremors, Skin colour, Twitches, Respiration, Convulsions, Palpebral closure, Bizarre/Abnormal/Stereotypic behaviour, 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 Behavioural Assessments and Sensory Reactivity Tests.
Functional Performance Tests
Motor Activity.
Purpose-built 44 infra-red beam automated activity monitors were used to assess motor activity. Animals were randomly allocated to the activity monitors. The
tests were performed at approximately the same time each day, under similar laboratory conditions. The evaluation period was thirty minutes for each animal. The percentage of time each animal was active and mobile was recorded for the overall thirty minute 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 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. The animal was pulled by the base of the tail until its grip was broken. 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 following parameters were observed:
Grasp response, Touch escape, Vocalisation, Pupil reflex, Toe pinch, Blink reflex, Tail pinch, Startle reflex, Finger approach.
Sacrifice and pathology:
Pathology
Adult males were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 43. Adult females were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 5 post partum. Surviving offspring were terminated via intracardiac overdose of sodium pentobarbitone. Any females which failed to achieve pregnancy or produce a litter were killed on or after Day 25 post coitum.
For all females, the uterus was examined for signs of implantation and the number of uterine implantations in each horn was recorded. This procedure was enhanced; as necessary, by staining the uteri with a 0.5% ammonium polysulphide solution (Salewski 1964).
All adult animals and offspring, including those dying during the study, were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.

GROSS PATHOLOGY:
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, Prostate, Brain, Seminal vesicles, Epididymides, Spleen, Heart, Testes, Kidneys, Thymus, Liver, Thyroid (weighed post-fixation with Parathyroid), Ovaries, Uterus (weighed with Cervix), Pituitary (post fixation).

HISTOPATHOLOGY:
Samples of the following tissues were removed from all animals and preserved in buffered 10% formalin, except where stated:
Adrenals, Aorta (thoracic), Pancreas, Bone & bone marrow (femur including stifle joint), Bone & bone marrow (sternum), Brain (including cerebrum, cerebellum and pons), Oesophagus, Caecum, Rectu, Salivary glands (submaxillary), Colon, Sciatic nerve, Duodenum, Skin (hind limb), Eyes*, Spinal cord (cervical, mid-thoracic and lumbar), Gross lesions, Heart, Spleen, Ileum (including peyer’s patches), Stomach, Jejunum, Thyroid/parathyroid, Kidneys, Trachea, Liver, Lungs (with bronchi) #, Thymus, Lymph nodes (cervical and mesenteric), Urinary bladder, Muscle (skeletal).

The following tissues from the remaining control and 1000 mg/kg bw/day animals and any animals which did not achieve a pregnancy were also processed:
Ovaries, Pituitary, Prostate, Coagulating gland, Seminal vesicles, Epididymides♦, Testes♦, Mammary gland, Mammary gland, Vagina.

* = eyes fixed in Davidson’s fluid
♦ = preserved in Bouin’s fluid then transferred to 70% Industrial Methylated Spirits (IMS) approximately forty-eight hours later
# = lungs were inflated to approximately normal inspiratory volume with buffered 10% formalin before immersion in fixative

In addition, sections of testes and epididymides from all control and 1000 mg/kg bw/day males were also stained with Periodic Acid-Schiff (PAS) stain and
examined.
All tissues were despatched to the histology processing Test Site (Propath UK Ltd, Willow Court, Netherwood Road, Rotherwas, Hereford, HR2 6JU) for processing. The tissues from five selected 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 haematoxylin and eosin for subsequent microscopic examination.
Since there were indications of treatment-related changes in the liver, examination was subsequently extended to include similarly prepared sections of liver from five animals per sex from the low and intermediate groups.
Microscopic examination was conducted by the Study Pathologist.
Other examinations:
Examinations into mating, pregnancy and parturition and litter examination were also carried out. Details of these examinations can be found in Sections 7.8.1 and 7.8.2 of this registration.
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, Body Weight Change, Food Consumption during gestation and lactation, Pre-Coital Interval, Gestation Length, Litter Size, Litter Weight, Sex Ratio, Corpora Lutea, Implantation Sites, Implantation Losses, Viability Indices, Offspring Body Weight, Offspring Body Weight Change, Offspring Surface Righting, Haematology, Blood Chemistry, Absolute Organ Weights, Body Weight- Relative Organ Weights.
Data were analysed using the decision tree from the ProvantisTM Tables and Statistics Module as detailed below in "any other information on materials and methods".
Clinical signs:
no effects observed
Description (incidence and severity):
No clinical signs were detected during the treatment period. There were no unscheduled deaths during the study.
Mortality:
no mortality observed
Description (incidence):
No clinical signs were detected during the treatment period. There were no unscheduled deaths during the study.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Food efficiency:
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
Daily visual inspection of water bottles did not reveal any significant intergroup differences.
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Urinalysis findings:
not examined
Behaviour (functional findings):
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
Please see "Details on results" below for more information.
Gross pathological findings:
no effects observed
Description (incidence and severity):
Please see "Details on results" below for more information.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Details on results" below for more information.
Histopathological findings: neoplastic:
no effects observed
Details on results:
BODY WEIGHT AND WEIGHT GAIN
No adverse effects on body weight change were detected for males during the treatment period of for females during the pre-pairing, gestation or lactation phases of the study.
Slightly low body weights were noted for females treated with 300 mg/kg bw/day when compared to controls on Day 0 of gestation. The significance achieved was minimal and considered to have arisen incidentally.

FOOD CONSUMPTION
No adverse effects on dietary intake were detected for males during the treatment period or for females during the pre-pairing, gestation or lactation phases of the study.
A slight increase in dietary intake was noted for females treated with 1000 mg/kg bw/day between gestation Days 0 to 7. This was an isolated finding and the minimal significance achieved was considered to have arisen incidentally.

HAEMATOLOGY
No toxicologically significant haematological changes were detected.
An increase in clotting times was noted for males treated with 1000 and 300 mg/kg bw/day when compared to controls. The significance achieved was minimal (p<0.05) in each case and all individual values were within the normally expected ranges for this parameter. As such, this increase was considered to have arisen incidentally.

CLINICAL CHEMISTRY
Bilirubin levels were raised for females treated with 1000 mg/kg bw/day when compared to controls (p<0.01) with one value outside of the normally expected ranges.
Bilirubin levels were also higher for females treated with 100 and 300 mg/kg bw/day however a dose-related response was not evident and all individual values were within the normally expected ranges. As such, these increases were considered to be unrelated to treatment with the test item.
Males treated with 1000 mg/kg bw/day showed a statistically significant increase in blood urea levels when compared to controls. All individual values were within the normally expected ranges, and as such, the minimal significance achieved was considered to have arisen incidentally.
Potassium levels were lower for females from all treated groups when compared to controls. The majority of individual values were within the normally expected ranges, and the significant differences were considered to have arisen due to one higher than expected control value. As such, these reductions were considered to be of no toxicological importance.

NEUROBEHAVIOUR
Behavioural Assessments
No treatment-related effects were detected for treated animals when compared to controls.
Any inter and intra group differences in scores were considered to be a result of normal variation for rats of the strain and age used and were of no toxicological importance.
Functional Performance Tests
No treatment-related effects were detected for treated animals when compared to controls.
An increase in hindlimb grip strength was noted for males treated with 1000 mg/kg bw/day. This was observed in only one out of three tests performed, and as such, was considered to have arisen incidentally.
Sensory Reactivity Assessments
Any inter and intra group differences in scores were considered to be a result of normal variation for rats of the strain and age used and were of no toxicological importance.

ORGAN WEIGHTS
Females treated with 1000 mg/kg bw/day showed a statistically significant increase in liver weights, both absolute and relative to terminal body weights, when compared to controls (p<0.01) with values for two animals outside of the normally expected ranges.
Males treated with 1000 mg/kg bw/day showed a statistically significant increase in thyroid/parathyroid weights when compared to controls (p<0.01) with three absolute weights values and two relative weights outside of the normally expected ranges.
Pituitary weights were higher for females treated with 1000 and 300 mg/kg bw/day when compared to controls. Although three higher than expected values were evident at 1000 mg/kg bw/day, in the absence of any histopathological correlates, these increases were considered attributable to two lower than expected control values.
Thymus weights were higher for males treated with 1000 and 300 mg/kg bw/day when compared to controls. The significance achieved in each case was minimal and in the absence of any histopathological correlates, these increases were considered to have arisen incidentally.
Females treated with 100 mg/kg bw/day showed a statistically significant reduction in thyroid/parathyroid weights when compared to controls. In the absence of a dose-related response, this finding was considered to be unrelated to test item toxicity.
A statistically significant increase in absolute and body weight-relative uterus and cervix weights was detected for females treated with 1000 mg/kg bw/day when compared to controls. Although two values were outside of the normally expected ranges, in the absence of any histopathological correlates, this finding was considered to have arisen incidentally.

GROSS PATHOLOGY
No treatment-related macroscopic abnormalities were detected.
One male treated with 100 mg/kg bw/day showed small testes and epididymides. This male did not produce a pregnancy. One control male showed a reddened left testis. Reddened lungs were observed for one female treated with 100 mg/kg bw/day and a malformed spleen was noted for one female treated with 300 mg/kg bw/day. Such findings are occasionally observed in rats of the strain and age employed; therefore these findings were of no toxicological importance.

HISTOPATHOLOGY: NON-NEOPLASTIC
Histopathology examinations revealed the following treatment-related effects:
LIVER: Centrilobular to diffuse hepatocellular hypertrophy was recorded for two females treated with 1000 mg/kg bw/day.
For Incidence and Mean Severity Grade of Main Findings in Liver, please see table below in "any other information on results".
All remaining findings were those commonly observed in rats of the age and strain employed.

OTHER FINDINGS:
For results on Reproductive Performance, please see Sections 7.8.1. and 7.8.2 of this registration.
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: The oral administration of Strontium Titanium Trioxide to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, resulted in treatment-related changes at 1000 mg/kg bw/day.
Critical effects observed:
not specified

Incidence and Mean Severity Grade of Main Findings in Liver

Finding Incidence/Mean Severity

Control

Low

Intermediate

High

5 M

5 F

5 M

5 F

5 M

5 F

5 M

5 F

Hepatocellular hypertrophy

-

-

-

-

-

-

-

2/1.5

Conclusions:
The oral administration of Strontium Titanium Trioxide to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, resulted in treatment-related changes at 1000 mg/kg bw/day. The effects detected were considered not to represent an adverse effect, therefore the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was considered to be 1000 mg/kg bw/day.
Executive summary:

Introduction.

The study was designed to investigate the systemic toxicity and potential adverse effects of the test item on reproduction (including offspring development) and is designed to be compatible with the requirements of the OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/ Developmental Toxicity Screening Test” (adopted 22 March 1996).

This study was also designed to be compatible with the 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 up to eight weeks (including a two week pre-pairing phase, pairing, gestation and early lactation for females), at dose levels of 100, 300 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, behavioural assessments, body weight change and food and water consumption were monitored during the study.

Pairing of animals within each dose group was undertaken on a one male: one female basis within each treatment group on Day 15 of the study, with females subsequently being allowed to litter and rear their offspring to Day 5 of lactation.

During the lactation phase, daily clinical observations were performed on all surviving offspring, together with litter size and offspring weights and assessment of surface righting reflex.

Extensive functional observations were performed on five selected males from each dose group after the completion of the pairing phase (during the final week of treatment), and for five selected parental females from each dose group on Day 4 post partum. Haematology and blood chemistry were evaluated prior to termination on five selected males and females from each dose group.

Adult males were terminated on Day 43, followed by the termination of all females and offspring on Day 5 post partum. Any female which did not produce a pregnancy was terminated on or after Day 25 post coitum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

Results.

Adult Responses:

Mortality. There were no unscheduled deaths.

Clinical Observations. There were no clinical signs detected.

Behavioural Assessment. No treatment-related effects were detected.

Functional Performance Tests. No treatment-related effects were detected.

Sensory Reactivity Assessments. No treatment-related effects were detected.

Body Weight. No adverse effects on body weight change were detected.

Food Consumption. No adverse effects on dietary intake were detected.

Water Consumption. Daily visual inspection of water bottles did not reveal any significant intergroup differences.

Reproductive Performance:

Mating. No treatment-related effects were detected for mating performance.

Fertility. No treatment-related effects on fertility were detected.

Gestation Lengths. No treatment-related effects were detected in the length of gestation between control and treated groups.

Litter Responses:

Offspring Litter Size, Sex Ratio and Viability. No toxicologically significant differences in litter size, viability or sex ratio were evident for offspring from treated litters when compared to those from the controls.

Offspring Growth and Development. No toxicologically important differences in litter weights, offspring weights or surface righting reflex were detected for litters from treated groups when compared to control litters. No treatment-related clinical signs were observed. Post-mortem examinations did not reveal any treatment-related macroscopic findings for offspring.

Laboratory Investigations:

Haematology. No toxicologically significant haematological changes were detected.

Blood Chemistry. Bilirubin levels were higher for females treated with 1000 mg/kg bw/day when compared to controls. There were no further treatment-related changes detected.

Pathology:

Necropsy. No treatment-related macroscopic abnormalities were detected.

Organ Weights. Females treated with 1000 mg/kg bw/day showed an increase in liver weights, both absolute and relative to terminal body weights, when compared to controls.

Histopathology. Histopathology examinations revealed the following treatment-related effects:

LIVER: Hepatocellular hypertrophy was recorded for two females treated with 1000 mg/kg bw/day.

Conclusion.

The oral administration of Strontium Titanium Trioxide to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, resulted in treatment-related changes at 1000 mg/kg bw/day. The effects detected were considered not to represent an adverse effect, therefore the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was considered to be 1000 mg/kg bw/day. The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day.

Endpoint conclusion
Endpoint conclusion:
adverse effect observed
Dose descriptor:
NOAEL
1 000 mg/kg bw/day
Study duration:
subacute
Species:
rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion
Endpoint conclusion:
no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion
Endpoint conclusion:
no study available

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

The oral administration of Strontium Titanium Trioxide to rats for a period of up to eight weeks (including two weeks pre-pairing, gestation and early lactation period for females) at dose levels of up to 1000 mg/kg bw/day resulted in treatment-related changes at 1000 mg/kg bw/day.

Bilirubin levels were raised for females treated with 1000 mg/kg bw/day when compared to controls. Females treated with 1000 mg/kg bw/day showed a statistically significant increase in liver weights, both absolute and relative to terminal body weights, when compared to controls. Hepatocellular hypertrophy was recorded for two females treated with 1000 mg/kg bw/day. Hepatocyte hypertrophy is associated with induction of metabolising enzymes in the liver, which is a normal response to xenobiotics. In the absence of any degenerative or inflammatory changes, this condition was considered to be adaptive in nature.

Males treated with 1000 mg/kg bw/day showed a statistically significant increase in thyroid/parathyroid weights when compared to controls. In the absence of any histopathological correlates, these increases were considered to be of minimal toxicological importance.

Based on the findings of this study, the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was therefore established at 1000 mg/kg bw/day.


Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
The oral administration of Strontium Titanium Trioxide to rats by gavage, at dose levels of 100, 300 and 1000 mg/kg bw/day, resulted in treatment-related changes at 1000 mg/kg bw/day. The effects detected were considered not to represent an adverse effect, therefore the ‘No Observed Adverse Effect Level’ (NOAEL) for systemic toxicity was considered to be 1000 mg/kg bw/day.

Justification for classification or non-classification

Based on the above information, the test material is not considered to be classified for Specific Target Organ Toxicity - repeated exposure.

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