Cerium vanadium tetraoxide

Repeated dose toxicity: oral

Administrative data

Endpoint:

repeated dose toxicity: oral, other

Remarks:

14-day toxicity study

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2014-10-09 to 2014-11-04

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

The study has limited relevance for human risk assessment for the following reasons: the study is designed as dose-range finding experiment for a sub-chronic study; 14- day exposure only; detailed clinical observations, haematology, clinical chemistry, and histopathology were not conducted; limited organ weight determination; individual data were not presented

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2015

Report date:

2015

Reference 2

Reference Type:

publication

Title:

14-day toxicity studies of tetravalent and pentavalent vanadium compounds un Harlan Sprague Dawley rats and B6C3F1/N mice via drinking water exposure

Author:

Roberts, G.K. et al.

Year:

2016

Bibliographic source:

Toxicology Reports 3: 531 - 538.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Sodium metavanadate was administered ad libitum to male and female Harlan Sprague Dawley rats (5 rats/sex/group) in dosed-water formulations made using pH 7 tap water at concentrations of 0, 125, 250, 500, 1000, and 2000 mg/L for 14 consecutive days. The following parameters were investigated: clinical signs, mortality/moribundity, body weights, water consumption, food consumption, gross pathology, and organ weights (liver, thymus, kidneys, testis, epididymis, ovary, heart, and lungs).

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Sodium metavanadate

EC Number:

237-272-7

EC Name:

Sodium metavanadate

Cas Number:

13718-26-8

Molecular formula:

NaVO3

IUPAC Name:

237-272-7

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): sodium metavanadate (supplier: MP Biomedicals, Santa Ana, CA)
- State of aggregation: white powder

Specific details on test material used for the study:

not specified

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on species / strain selection:

This strain (and species) was designated by the National Institute of Environmental Health Sciences (NIEHS) and is commonly used for chemical safety evaluation.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan, Indianapolis, IN
- Age at first dose: 39 to 45 days
- Weight at study initiation: males: 159.2 to 182.9 grams; females: 114.1 to 136.0 grams
- Housing: group housed, 5/cage, in solid polycarbonate cages (22"L × 12.5"W × 8"H; Lab Products, Inc. (Seaford, DE)); bedding material: irradiated Sani-Chips hardwood chips (P.J. Murphy Forest Products Corporation, Montville, NJ)
- Diet (ad libitum): irradiated NTP-2000 wafer feed (Zeigler Brothers, Inc. (Gardners, PA))
- Water (ad libitum): tap water
- Quarantine period: 12 days

Following randomization, two male and three female rats which had not been selected for study were designated for quarantine serology collection and gross necropsy. All results for serological analysis were without any abnormal findings. Gross necropsy did not reveal gross abnormalities or disease. The rats were also examined for the presence of internal and external parasites. No parasites were noted.

ENVIRONMENTAL CONDITIONS
- Temperature: 19.4 °C to 22.8 °C
- Relative humidity: 39 % to 59 %
- Air changes: min. 10 changes/hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: drinking water

Details on route of administration:

The potential for human exposure occurs primarily due to widespread occurrence of sodium metavanadate as a drinking water contaminant and its use as a dietary supplement.

Vehicle:

water

Remarks:

adjusted to pH 7

Details on oral exposure:

VEHICLE
The vehicle was prepared by filling a 100-L Nalgene tank with approx. 70 L of tap water. The pH of the tap water was adjusted to 6 to 8 with hydrochloric acid and/or sodium hydroxide while stirring with an overhead stirrer. A 10-L quantity of the vehicle was transferred directly into a 10-L carboy with a spigot.

PREPARATION OF DOSING SOLUTIONS:
Formulations containing test article were prepared using the remaining 60-L quantity of pH adjusted tap water from lowest to highest concentration. A measured amount of test article was placed into individual weighing containers, then analytically transferred directly into individual calibrated mixing/dosing carboys containing approx. 90 % of the final volume of vehicle. The weighing container was rinsed with vehicle at least three times and the rinse was added to the mixing/dosing carboy.
The contents of the mixing/dosing carboy were stirred using an overhead stirrer for approx. 1 hour until all the test article was visibly in solution. The formulations were diluted to final volume with vehicle and stirred for approx. 2 minutes.
The formulations were stored refrigerated (approx. 5°C) and were used within 42 days after formulation.

Drinking bottles containing the formulation were exchange at least every 4 days.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

1) Formulation analysis
Formulations prepared in dosed drinking water before administration were analyzed both prior to and after administration to the animals. All analyses used a HPLC with ultraviolet method detection that was validated prior to the start of the study. Animal room and carboy samples were collected.

Results:
All average pre-administration values were within 10 % of target concentrations (0.1 % to 1 %).
All average post-administration values were within 10 % of target and pre-administration values for each concentration (sample formulation left in drinking bottle: -0.5 % to 1.9 %; sample collected from carboy: -0.1 to 0.8 %)..
Carboy values agreed well with those from pre-administration and animal room values.

2) Nuclear Magnetic Resonance (NMR) spectroscopy for vanadium speciation
Samples of formulations stored at 2 to 8°C were submitted for NMR analysis the day after they were prepared and analyzed the same day. Subsequent NMR analysis was conducted after study termination on samples collected for post-administration formulation analysis [a portion of each animal room sample (drinking bottles) and each carboy sample was submitted for NMR analysis].

Results:
Comparison shows very good consistency of vanadate species present between the original formulation concentrations and those of the drinking bottle and carboy samples at the same concentrations, although the species present at each concentration vary significantly.

Duration of treatment / exposure:

14 days (exception: 1000 mg/L and 2000 mg/L groups were treated for 7 days only)

Frequency of treatment:

ad libitum

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

125 mg/L drinking water

Remarks:

actual dose received: males: 12.924 mg/kg/day; females: 14.458 mg/kg/day

Doses / concentrations 2

Dose / conc.:

250 mg/L drinking water

Remarks:

actual dose received: males: 24.075 mg/kg/day; females: 25.258 mg/kg/day

Doses / concentrations 3

Dose / conc.:

500 mg/L drinking water

Remarks:

actual dose received: males: 39.057 mg/kg/day; females: 42.527 mg/kg/day

Doses / concentrations 4

Dose / conc.:

1 000 mg/L drinking water

Remarks:

actual dose received: males: 42.335 mg/kg/day; females: 60.200 mg/kg/day

Doses / concentrations 5

Dose / conc.:

2 000 mg/L drinking water

Remarks:

actual dose received: males: 47.459 mg/kg/day; females: 42.557 mg/kg/day

No. of animals per sex per dose:

5 males / 5 females

Control animals:

yes, concurrent vehicle

Details on study design:

not specified

Positive control:

none

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule:
mortality/moribundity: twice daily (at least 6 hours between observations)
Clinical signs: daily and at removal from study
- Cage side observations checked: clinical signs as well as mortality or moribundity

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
- Time schedule for examinations: prior to administration (study day 1) as well as on study days 4, 8, 11, and 15 (at removal from study)

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Mean daily diet consumption/group calculated as g food/kg body weight/day: Yes, feeder weights were recorded twice weekly
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

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 consumption was measured by recording the weights of the bottles before and after presentation to the animals; bottles were changed at least twice weekly.

OPHTHALMOSCOPIC EXAMINATION: No
HAEMATOLOGY: No
CLINICAL CHEMISTRY: No
URINALYSIS: No
NEUROBEHAVIOURAL EXAMINATION: No
IMMUNOLOGY: No

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: No

All rats were sacrificed and subjected to a complete necropsy with gross examination. Necropsies were performed on the day of termination or of the animal being found dead.

Organ weights:
Organ weights were determined from all rats surviving until scheduled termination on Study Day 15. Organ weights were recorded for the liver, thymus, right and left kidney, right and left testis, right and left epididymis, right and left ovary, heart, and lungs.

Statistics:

All appropriate quantitative in-life data collected were analyzed for test article effects by parametric or nonparametric analysis of variance (ANOVA). For all data, normality was determined by the Shapiro-Wilks test and homogeneity of variances was determined by Levene’s test. Data may have been log-transformed to meet parametric assumptions. For parametric data determined to be normally distributed and homogenous among groups, an ANOVA F-test was used to determine whether there were differences among the group means. If the ANOVA F-test was significant, then tests for differences between the vehicle group and each of the comparison groups were conducted using Dunnett’s test, which adjusts for multiple comparisons. For nonparametric data that were not normally-distributed and/or nonhomogenous, a Kruskal-Wallis test was used to determine whether there are differences among the group means. If the Kruskal-Wallis test was significant, then tests for differences between the vehicle group and each of the comparison groups were conducted using Wilcoxon tests and the Bonferroni-Holm method to correct for multiple comparisons.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

mortality observed, non-treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Neuropathological findings:

no effects observed

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Details on results:

CLINICAL SIGNS
- 0, 125, 250, and 500 mg/L: no clinical signs were reported for males and females.

1) Males
- 2000 mg/L: shallow breathing (1/5 males; Days 7 and 8), ruffled coat (3/5 males; Days 7 and 8), brown discharge eye (1/5 males; Days 7 and 8), red discharge nose/snout (1/5 males; Day 8), abnormal gait (3/5 males; Days 7 and 8), hunched posture (2/5 males; Day 8), and thin (5/5 males; Days 6 to 8)
- 1000 mg/L: shallow breathing (1/5 males; Days 7 and 8), ruffled coat (2/5 males; Days 7 and 8), brown discharge eye (3/5 males; Days 7 and 8), red discharge nose/snout (1/5 males; Day 8), abnormal gait (2/5 males; Days 7 and 8), hunched posture (2/5 males; Days 7 and 8), and thin (3/5 males; Days 7 and 8)

2) Females
- 2000 mg/L: ruffled coat (5/5 females; Days 6 to 8), red discharge nose/snout (1/5 females; Day 8), abnormal gait (2/5 females; Days 6 to 8), hunched posture (1/5 males; Day 8), lethargic (1/5 females; Day 6) and thin (4/5 females; Days 7 and 8)
- 1000 mg/L: thin (3/5 females; Day 8)

MORTALITY
- 0, 125, 250, and 500 mg/L: all males and females survived to their scheduled termination on Day 15.

1) Males
- 2000 mg/L: 1/5 males was found dead on day 6 and 4/5 males were sacrificed (Day 8) before study termination on Day 15.
- 1000 mg/L: 5/5 males were sacrificed (day 8) before study termination on Day 15.

2) Females
- 2000 mg/L: 1/5 females was found dead on day 7 and 4/5 females were sacrificed (Day 8) before study termination on Day 15.
- 1000 mg/L: 5/5 females were sacrificed (day 8) before study termination on Day 15.

The clinical signs, decreasing body weights, and low food and water consumption, led to the decision for early termination of surviving males and females in the 1000 and 2000 mg/L groups on day 8.

BODY WEIGHT AND WEIGHT CHANGES
1) Males
- 1000 and 2000 mg/L: at early termination (Day 8), 29 % and 33 % body weight reduction occurred, respectively.
- 250 and 500 mg/L: at study termination (Day 15), body weights were significantly lower, but did not exceed a 9 % reduction compared to vehicle.
- 250 and 500 mg/L: over the course of the exposure period (Days 1 through 15), 21 % and 30 % body weight gain reduction, respectively.

2) Females
- 1000 and 2000 mg/L: at early termination (Day 8), 15 % and 32 % body weight reduction occurred, respectively.
- 500 mg/L: over the course of the exposure period (Days 1 through 15), 25 % body weight gain reduction

FOOD CONSUMPTION
Food mean consumption (g/day) decreased with increasing concentration during the first collection period (Days 1 to 8), and during subsequent collections, for males and females.

1) Males
- 1000 and 2000 mg/L: prior to early termination (Day 8), food consumption was approx. 55 and 63 % reduced compared to the vehicle group, resepctively. During the first collection period (Days 1 through 8), reductions in food consumption per kilogram body weight (g/kg/day) were 45 and 55 % reduced, respectivley.
- 125, 250 and 500 mg/L: over the course of the study (Days 1 to 15), effects on food mean consumption (g/day) were limited to the 250 and 500 mg/L groups which were 12 and 14 % lower than vehicle, respectively. Over the course of the study (Days 1 to 15), food consumption per kilogram body weight (g/kg/day) in the 125, 250, and 500 mg/L groups did not exceed an 8 % difference from their respective 0 mg/L groups.

2) Females
- 1000 and 2000 mg/L: prior to early termination (Day 8), food consumption was approx. 31 and 60 % reduced compared to the vehicle group. During the first collection period (Days 1 through 8), reductions in food consumption per kilogram body weight (g/kg/day) were 23 and 51 % reduced, respectively.
- 125, 250 and 500 mg/L: Over the course of the study (Days 1 to 15), food consumption per kilogram body weight (g/kg/day) in the 125, 250, and 500 mg/L groups did not exceed an 8 % difference from their respective 0 mg/L groups.

WATER CONSUMPTION
Water mean consumption (g/day) generally decreased with increasing concentration for each collection period and over the course of the study (Days 1 to 15). Similar trends were apparent for males and females.
Water consumption per kilogram body weight (g/kg/day) also decreased with increasing concentration for each collection period and over the course of the study. Similar trends were apparent for males and females.

1) Males
- 1000 and 2000 mg/L: at early termination on Day 8, group mean water consumption (g/day) was 71 % 84 % lower than vehicle, respectively. At early termination (Day 8), water consumption per kilogram body weight (g/kg/day) was 65 % and 80 % lower than vehicle, respectively.
- 250 and 500 mg/L: over the course of the study (Days 1 through 15), reductions in group mean water consumption (g/day) were limited to the 250 and 500 mg/L groups, which were approx. 14 % and 32 % lower compared to the vehicle group, respectively. Over the course of the study (Days 1 through 15), reductions in water consumption per kilogram body weight (g/kg/day) were limited to the 250 and 500 mg/L groups, which were approx. 11 % and 28 % lower compared to the vehicle group, respectively.

For males, a 2-fold increase in test item concentration (125, 250, 500, 1000, and 2000 mg/L) resulted in 1.9-, 1.5-, 1.0-and 1.1-fold increases in chemical intake (mg/kg/day) during the first collection period (Days 1 to 8), and resulted in 1.9-and 1.6-fold increases in chemical intake for the 125, 250, and 500 mg/L groups over the course of the exposure period (Days 1 to 15). At early termination (Day 8), 1000 and 2000 mg/L males consumed similar dosages as 500 mg/L males.

2) Females
- 1000 and 2000 mg/L: at early termination on Day 8, group mean water consumption (g/day) 57 % and 86 % lower than vehicle, respectively. At early termination (Day 8), water consumption per kilogram body weight (g/kg/day) was 52 % and 83 % lower than vehicle, respectively.
- 250 and 500 mg/L: over the course of the study (Days 1 through 15), reductions in group mean water consumption (g/day) were limited to the 250 and 500 mg/L groups, which were approx. 16 % and 31 % lower compared to the vehicle group, respectivley. Over the course of the study (Days 1 through 15), reductions in water consumption per kilogram body weight (g/kg/day) were limited to the 250 and 500 mg/L groups, which were approx. 13 % and 27 % lower compared to the vehicle group, resepctively.

For females, a 2-fold increase in test item concentration (125, 250, 500, 1000, and 2000 mg/L) resulted in 1.7-, 1.6-, 1.3-and 0.7-fold increases in chemical intake (mg/kg/day) during the first collection period (Days 1 to 8), and resulted in 1.7-fold increases in chemical intake for the 125, 250, and 500 mg/L groups over the course of the exposure period (Days 1 to 15). At early termination (Day 8), females in the 2000 mg/L group consumed approx. 70 % of the dosage consumed by females in the 1000 mg/L group.

ORGAN WEIGHT FINDINGS INCLUDING ORGAN/BODY WEIGHT RATIOS
NOTE: no organ weights were recorded for animals in the 1000 and 2000 mg/L groups.

1) Males:
- thymus: mean thymus-to-terminal body weight values for 250 and 500 mg/L males were increased by 17 % and 16 %, respectively. The differences were not statistically significant. There were no corresponding differences in mean thymus weight for either group, and the differences in the ratios were considered to be a consequence of reduced terminal body weight.

- heart: mean absolute heart weight was slightly decreased (10 %) in 500 mg/L males, while the heart-to-terminal body weight ratio was unchanged from the 0 mg/L group, indicating that the mean organ weight change was a result of overall reduction in terminal body weight. There were no appreciable differences in heart weight values in any other concentration group.

- lung: mean absolute lung weights were decreased in all measured male concentration groups. The effect was not concentration dependent. The maximum reduction (only statistically significant difference) came in the 250 mg/L group, which was 44 % reduced, while the 125 and 500 mg/L groups were reduced by 19 and 33 %, respectively. The same pattern was present for lung-to-terminal body weight values, with reductions of 20, 39, and 26 % for 125, 250, and 500 mg/L groups.

- liver: mean absolute liver weights were significantly increased in 125 and 250 mg/L males (18 and 17% , respectively), but were increased by only 5 % in 500 mg/L males. Mean liver-to-body weight ratios were variable, with increases of 17 %, 26 %, and 15 % in 125, 250, and 500 mg/L groups compared to the 0 mg/L group. This variability reflects the influences of fluctuating organ weight across groups in the face of decreasing terminal body weight.

- kidneys: mean absolute left and right kidney weights were increased in 250 mg/L males, with this increase reaching statistical significance for the right kidney value. There were no apparent differences for either value in 125 and 500 mg/L male groups. A similar pattern was seen for left and right kidney-to-terminal body weight values. In these cases, both 250 mg/L values increases were significant.

- testis: mean left and right testis-to-terminal body weight values were increased in 500 mg/L males (statistical significance for the right testis value). There were no corresponding changes in mean absolute left or right testis weight, and the differences in the testis-to-terminal body weight ratios were considered to be a consequence of reduced terminal body weight for this group.

- epididymis: mean absolute left epididymis weight and left epididymis-to-terminal body weight values were reduced by 11 and 12 %, respectively, in the 125 mg/L male group, with the latter decrease reaching statistical significance. There were no differences for the 250 mg/L group, and the left epididymis-to-terminal body weight value was increased in 500 mg/L males; although without a corresponding difference in mean value for this group, this change is considered to be a consequence of reduced terminal body weight. For the right epididymis, the only change was an increase in organ-to-terminal body weight ratio in the 500 mg/L group, also without a corresponding increase in right epididymis weight and also attributed to reduced terminal body weight in this group.

2) Females:
- thymus: there were reductions in mean thymus weight and thymus-to-terminal body weight values. These changes did not show a concentration-specific response. The greatest differences were in the 250 mg/L group, with 15 % and 10 % reductions for mean thymus weight and thymus-to-terminal body weight, respectively, while there were no differences for either value in the 500 mg/L females.

- heart: there were no appreciable differences in heart weight values in any concentration group.

- lung: lung weight and lung-to-terminal body weight ratios were decreased in 250 and 500 mg/L groups in a concentration-dependent manner (not statistical significant).

- liver: no consistent differences in mean liver weight or mean liver-to-terminal body weights were observed among treated females.

- kidneys: no consistent differences in mean left or right kidney weight or mean kidney-to-terminal body weights were observed among treated females.

- ovary: mean right ovary weight and ovary-to-body weight values were decreased in all female groups examined, although the differences did not exhibit a concentration response (mean weights were reduced by 18, 10, and 32 %, respectively for the 125, 250, and 500 mg/L groups, with similar values and pattern of change for right ovary-to-terminal body weight values) and never reached statistical significance. There were also no corresponding differences in left ovary weight values.

GROSS PATHOLOGICAL FINDINGS
1) Males
- 250 mg/L: hepatodiaphragmatic nodule was observed in one male.
2) Females:
- 0 mg/L: dark discolouration of the thymus was observed in one female.

Effect levels

Remarks on result:

not determinable because of methodological limitations

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Sodium metavanadate exposure in drinking water resulted in 100 % survival in the 0, 125, 250, and 500 mg/L groups (equivalent to 12.924, 24.075, and 39.057 mg/kg/day for males and 14.458, 25.258, 42.527 mg/kg/day for females). Due to early deaths in the 2000 mg/L group, clinical observations, and low body weights and water and food consumption, the remaining animals in the 1000 and 2000 mg/L groups (equivalent to 42.335 and 47.459 mg/kg/day for males and 60.200 and 42.557 mg/kg/day for females) were terminated early on Day 8. Clinical abnormalities were limited to 1000 mg/L males and 2000 mg/L males and females and included shallow breathing, ruffled coat, eye discharge, nose/snout discharge, abnormal gait, hunched posture, lethargy, and/or thin appearance. Females in the 1000 mg/L group were also described as thin prior to early termination.
At study termination, body weight gain reductions occurred in males in the 250 and 500 mg/L groups and females in the 500 mg/L group. Reductions in food consumption (g/day) were limited to males in the 250 and 500 mg/L groups; however, when normalized by body weight, food consumption values were similar at the intermediate and vehicle concentrations. Prior to early termination on Day 8, males in the 1000 and 2000 mg/L groups consumed similar dosages (mg/kg/day) to 500 mg/L males. Females in the 2000 mg/L group consumed approximately 70 percent of the dosage (mg/kg/day) of females in the 1000 mg/L group; thus, palatability issues may have contributed to body weight reductions in the 1000 and 2000 mg/L groups, leading to mortality and moribundity that was not seen in the lower concentrations.
Effects on water consumption also occurred for males and females in the 250 and 500 mg/L groups, but when normalized to body weight, reductions were correlated with the reduction in weight gains seen in both male and female rats, indicating water consumption correlated with body size for these groups.
Increased liver weights (absolute and/or liver-to-body weight ratios) were noted for all groups of sodium metavanadate-exposed males at study termination.

Overall, a confounding variable in this study is the reduced water consumption, which might be due to palatability, and the potential dehydration of the animals. Some of the clinical signs can be attributed to dehydration. In addition, lower water consumption might have caused the body weight reduction observed at the 2000 mg/L dose level.

Due to the limited study design, short exposure duration of only 14 days, restricted examination of the animals (detailed clinical observations, haematology, clinical chemistry, and histopathology missing; limited organ weight determination), and lack of reporting the individual data, the study will not be used for hazard and risk assessment purposes but as supplementary information.