Ammonium perrhenate

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

02 Jul 2012 to 12 Oct 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: A good quality guideline study, carried out to GLP

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

yes

Remarks:

Only minor deviations, for example in temperature and humidity which were not determined to have any impact on the integrity of the study or results

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Ammonium perrhenate

EC Number:

237-075-6

EC Name:

Ammonium perrhenate

Cas Number:

13598-65-7

Molecular formula:

H4N.O4Re

IUPAC Name:

Ammonium oxido(trioxo)rhenium

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

- Name of test material (as cited in study report): Ammonium perrhenate (also known as Ammonium tetraoxorhenate (VII))
- Substance type: Technical product
- Physical state: White solid
- Analytical purity: 99.95%
- Purity test date: 5 Apr 2012
- Lot/batch No.: 11411
- Expiration date of the lot/batch: 31 Oct 2012
- Storage condition of test material: Ambient / Dark
- Other: Supplied by Heraeus Precious Metals GmbH & Co.KG

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Limited, Margate, Kent, UK
- Age at study initiation: 8-10 weeks
- Weight at study initiation: (P) Males: 305-381 g; Females: 224-282 g
- Housing: Polycarbonate cages with stainless steel grid tops and solid bottoms, approximately 61 x 43.5 x 24 cm. White paper tissue was supplied to females as nesting material from Day 20 of gestation.
- Diet (e.g. ad libitum): Rat and Mouse Breeder Diet No. 3 (Expanded), supplied by Special Diets Services Limited, Witham, Essex, UK provided ad libitum
- Water (e.g. ad libitum): Public water supply (Scottish Water, Edinburgh, UK) was available ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23 (daily monitoring indicated that temperature went above the target range on 1 occasion. Temp reached a max of 24 deg C for about 1.5 hr. This was not considered to have affected the outcome or integrity of the study).
- Humidity (%): 40-70 (humidity was above target ranges on several occasions - actual range 48-77%. Daily target average humidity was within the target range and deviations were short in duration. They were considered not to have had any impact on the outcome or integrity of the study).
- Air changes (per hr): minimum 10
- Photoperiod (hrs dark / hrs light): 12 hours light / dark

IN-LIFE DATES: From: To: Dosing was initiated on 09 Jul 2012. In-life phase of the study was completed on 24 Aug 2012

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 40% PEG400 in Milli-Q water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Dosing formulations were prepared weekly, stored in a refrigerator set to maintain 4 deg C, and dispensed daily. They were prepared by adding an appropriate amount of vehicle to the required amount of test item and were mixed by magnetic stirring until a visible clear solution was obtained. The dosing formulations were removed from the refrgerator and stirred for at least 30 mins prior to dosing and continuously during dosing.

Homogeneity and stability were previously established by Charles River (Study No. 428793).

All formulations were used within an established 8 day stability period.

VEHICLE
- Concentration in vehicle: 0, 11, 33, 100 mg/ml (0, 110, 330, 1000 mg/kg bw/day dose levels, respectively)
- Amount of vehicle (if gavage): Dose volume 10 ml/kg bw

Details on mating procedure:

- M/F ratio per cage: Pairings were on a one male to one female basis
- Length of cohabitation: Until mating or 14 nights
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged (how): Mated females were tranferred to individual solid bottom cages. White paper tissue was supplied as nesting material from Day 20 of gestation. The bedding was considered not to contain any additional substances in sufficient concentration to have had any influence on the outcome of the study. A Certificate of Analysis for the bedding is retained at Charles River, Edinburgh.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Duplicate dosing formulations were sampled for analysis at 1 and 4 weeks. Analyses were performed by ICP-Optical Emmission Spectroscopy using a validated analytical procedure. Results of the sample concentrations were considered acceptable as they were all within +/-10% of the theoretical concentrations.

Duration of treatment / exposure:

Males were dosed for 4 weeks prior to mating. Females were dosed 2 weeks prior to mating, throughout mating and through to at least day 4 of lactation.

Frequency of treatment:

Once daily

Details on study schedule:

The females were allowed to litter normally. Any observed difficulty or prolongation of parturition was recorded. The day of birth of the litter (day on which the first pups were born) was designated as Day 0 of lactation. The duration of gestation was calculated.

The numbers of live and dead pups born in each litter was recorded as soon as possible after completion of parturition on Day 0 of lactation. The live pups were counted and examined for the presence of milk in the stomach and for any externally visible abnormalities daily. Each litter was weighed en masse (by sex) on Days 1 and 4 of lactation. Where practicable, any pups that were found dead or killed during lactation were sexed and appropriately examined as above. Any externally abnormal decedent pups were to be persevered. However, all decedent pups were found to be externally normal and were discarded following examination.

Deficiencies in maternal care were recorded: inadequate construction or cleaning of the nest, pups left scattered and cold, physical abuse of pups, or apparently inadequate lactation or feeding. White paper tissue was supplied to each mother for incorporation in the nest which was replaced when it became soiled.

Doses / concentrations

Remarks:

Doses / Concentrations:
110, 330, 1000 mg/kg bw/day
Basis:
nominal in water

No. of animals per sex per dose:

10 males and 10 females per dose

Control animals:

yes, concurrent vehicle

Details on study design:

Dose levels were agreed after review of existing relevant toxicological data including a 7 day dose range finding study (Charles River Study No. 495676) where dose levels up to 1000 mg/kg bw/day produced no adverse reaction to treatment.

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Once during the pre-treatment period and weekly thereafter.
- Cage side observations included: posture/condition (including e.g. prostration, lethargy, writhing, circling, breathing abnormalities, gait abnormalities, tremor, fasciculation, convulsions, biting of cage components or self mutilating, vocalisations, piloerection); ease of removal from cage; body temperature; condition of eyes and coat; presence of salivation, overall ease of handling.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once each week, including appearance, movement and behaviour patterns, skin and hair condition, eyes and mucous membranes, respiration and excreta

BODY WEIGHT: Yes
- Time schedule for examinations: Body weights were recorded one week prior to the start of treatment. From the start of treatment, individual body weights were recorded daily.

FOOD CONSUMPTION:
- Food consumption was measured for both sexes weekly, starting 1 week prior to dosing until pairing for mating. After pairing, the female food consumption was measured over Days 0-7, 7-14 and 14-20 of gestation and Days 0-4 of lactation. Male food consumption did not recommence after pairing for mating.

WATER CONSUMPTION: No

OTHER: Details of additional observations and examinations are given under IUCLID 7.5

Sperm parameters (parental animals):

Epididymis and testis were weighed at necropsy.

Litter observations:

The females were allowed to litter normally. Any observed difficulty or prolongation of parturition was recorded. The day of birth of the litter (day on which the first pups were born) was designated as Day 0 of lactation. The duration of gestation was calculated.

The numbers of live and dead pups born in each litter was recorded as soon as possible after completion of parturition on Day 0 of lactation. The live pups were counted and examined for the presence of milk in the stomach and for any externally visible abnormalities daily. Each litter was weighed en masse (by sex) on Days 1 and 4 of lactation.

Where practicable, any pups that were found dead or killed during lactation were sexed and appropriately examined as above. Any externally abnormal decedent pups were to be persevered. However, all decedent pups were found to be externally normal and were discarded following examination.

Deficiencies in maternal care were recorded: inadequate construction or cleaning of the nest, pups left scattered and cold, physical abuse of pups, or apparently inadequate lactation or feeding. White paper tissue was supplied to each mother for incorporation in the nest which was replaced when it became soiled.

Postmortem examinations (parental animals):

SACRIFICE
The males were killed when mating was completed and the animals had been dosed for at least 4 weeks.
The females (and litters) were killed between Day 5 and 7 of lactation.

GROSS NECROPSY & HISTOPATHOLOGY / ORGAN WEIGHTS
Premature decedents were necropsied with a view to diagnosis of the cause of the animal’s condition or cause of death. An external examination was followed by inspection of the cranial, thoracic and abdominal contents. Representative samples of abnormal tissues, together with any other tissues considered appropriate, were fixed in neutral buffered 10% formalin. The reproductive tracts of females were examined for signs of implantation and the number of implantation sites recorded.

All adult animals surviving to scheduled euthanasia were subjected to a complete necropsy examination which included evaluation of the carcass and musculoskeletal system: all external surfaces and orifices; cranial cavity and external surfaces of the brain; and thoracic, abdominal, and pelvic cavities with their associated organs and tissues. The reproductive tracts of all females were examined for signs of implantation, the number of any implantation sites being recorded and the numbers of corpora lutea graviditatis on the ovaries were counted.

The following organs were weighed at necropsy for all adult animals: brain; epididymis; adrenal gland; pituitary gland; prostate gland; thyroid gland; heart; kidney; liver; lung; ovary; spleen; testis; thymus; uterus.

A comprehensive histopathological evaluation of tissues was undertaken for 5 males and 5 females in the Control and High dose groups, as outlined under the Repeated Dose Toxicity section in IUCLID 7.5.

Postmortem examinations (offspring):

Where practicable, animals found dead or killed prematurely were sexed, then checked for the presence of milk in the stomach and for the presence of any externally visible abnormalities. Surviving pups were also examined for externally visible abnormalities. All pups were then discarded.

Statistics:

Unless otherwise stated, statistical tests were two-sided and performed at the 5% significance level. Pairwise comparisons were only performed against the control group. Body weight, food consumption, haematology, coagulation, clinical chemistry and selected FOB and motor activity data was analysed for homogeneity of variance using the ‘F Max' test. If the group variances appeared homogeneous, a parametric ANOVA was used and pairwise comparisons were made using Fisher’s F protected LSD method via Student's t test ie pairwise comparisons were made only if the overall F test was significant. If the variances were heterogeneous, log or square root transformations were used in an attempt to stabilise the variances. If the variances remained heterogeneous, then a Kruskal-Wallis nonparametric ANOVA was used and pairwise comparisons were made using chi squared protection (via z tests, the non-parametric equivalent of Student's t test). Organ weight data was analysed as above, and by analysis of covariance (ANCOVA) using terminal body weight as the covariate.

Incidence data was analysed as proportions in a Kruskal-Wallis analysis, or by categorical methods using contingency tables with the Fisher’s Exact Probability test or the Chi-squared test.

Reproductive indices:

Fertility Index (male) = Number siring a litter/Number paired

Fertility Index (female) = Number pregnant/Number paired

Gestation Index = Number bearing live pups/Number pregnant

Birth Index = Total number of pups born (live and dead)/Number of implantation scars

Live Birth Index = Number of pups live on Day 0 of lactation/Total number born (live and dead)

Offspring viability indices:

Viability Index = Number of pups live on Day 4 of lactation/Number live on Day 0

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Two animals were prematurely killed at 1000 mg/kg bw/day and considered to be treatment-related, and there was an increased incidence and severity of clinical observations in both sexes. Slight changes were observed at 330 mg/kg bw/day.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Males at 1000 mg/kg bw/day had decreased mean body weight gain from week 1. There was reduced food consumption in both sexes.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Males at 1000 mg/kg bw/day had decreased mean body weight gain from week 1. There was reduced food consumption in both sexes.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Treatment at 1000 mg/kg bw/day in both sexes was associated with effects on the thyroid, bone marrow and spleen. Males at this dose also had effects on the pituitary gland.

Other effects:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Two animals were prematurely killed in the top dose group of 1000 mg/kg bw/day and considered to be treatment-related, with cause of death in both due to widespread haemorrhage and congestion.

At 1000 mg/kg bw/day there was an increase in the incidence and severity of clinical observations in both males and females, when compared to controls. Dose related signs included ploughing, body hunched, piloerection, rolling gait, walking on tip toes, redness of the ears/extremities, swelling of the ears/feet/muzzle/ventral neck and abdomen, excess salivation, pale ears/extremities, excessive chewing of cage parts/shavings (females only), eyes partially closed (males only) and irregular respiration. The observed redness of the ears/extremities and the swelling of the ears/feet/muzzle/ventral neck and abdomen, was evident in most high-dose animals from ca Study Day 10/11 onwards. The redness of the ears/extremities became more transient as dosing continued with most animals ceasing to show these signs beyond Study Day 19. A similar pattern of recoverability was apparent with the signs of swelling in the females; however the signs of swelling remained evident in the majority of males until necropsy. At 330 mg/kg bw/day there was a slight increase in ploughing in both males and females and excess salivation in males only. No treatment-related clinical observations were noted at 110 mg/kg bw/day.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
In males at 1000 mg/kg bw/day, a statistically significant decrease in mean body weight gain was observed from Week 1 onwards, when compared to Controls. At 330 mg/kg bw/day in males there was a slight reduction in mean body weight gain, when compared to Controls. The group mean body weight gain at 330 mg/kg bw/day was 122g over Days 0-28 compared to 130g in Controls, which is a 6% reduction in body weight gain compared to Controls. This did not achieve statistical significance and the group mean value has been slightly skewed by the weights of 2 outlier males. Both these animals started to show a reduced body weight gain from ca Week 1/2 of the study onwards and when these two animals are removed from the group mean body weight gain, the group mean gain from Day 0-28 is 129g compared to 130g in Controls. As the reduction in body weight gain of these two animals is slight and due to all other males at this level having weight gains comparable to Control, this reduced body weight gain could not be positively associated with treatment. At 110 mg/kg bw/day the group mean body weight and the group mean body weight gain in males were similar to Controls.

In all treated groups, group mean body weight gain of females prior to mating was similar to Control. In females at 1000 mg/kg bw/day, a reduction in group mean body weight gain was observed over Gestation Days 0-20 and with increased severity during Lactation Days 0-4, when compared to Controls. At 1000 mg/kg bw/day group mean body weight gain over Day 0-20 of gestation was 13% lower than Controls and over Days 1-4 of lactation was 59% lower than Controls.

During the first two weeks of dosing, males dosed at 1000 mg/kg bw/day had a statistically significant reduction in group mean food consumption, when compared to Controls. Prior to mating, females at 1000 mg/kg bw/day had a very slight reduction in group mean food consumption compared to Controls. During the 2 weeks prior to mating, high-dose females ate an average of 5% less food than Control animals. This did not achieve statistical significance and the change was considered minor. At 1000 mg/kg bw/day in females during gestation and lactation, there was a notable reduction in group mean food consumption when compared to Controls. Over Day 0-20 of gestation high-dose females ate an average of 15% less food than Controls, rising to 19% reduction in food consumption over Day 0-4 of lactation, when compared to Controls. At levels up to 330 mg/kg bw/day food consumption performance in both sexes was similar to Control.

REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS)
Sperm measurements were not made. There was no effect on the testis or epididymis.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
At 1000 mg/kg bw/day there was an apparent increase in the number of nights to positive mating and the median number of nights to a positive mating. In this group, 6/10 females mated after 4 nights compared to 4 in Controls. Although this is higher than expected, all 6 of these females mated on the first possible oestrus and vaginal smear results indicate the animals were cycling normally. This suggests that the increased number of nights to positive mating is incidental and not related to treatment with Ammonium Perrhenate.

The mean duration of gestation, the male and female fertility indices and the number of females producing a live litter were similar in all groups. At 330 and 1000 mg/kg bw/day there was one non-pregnant female at each of these levels resulting in a slightly reduced fertility index, when compared to Control. This is within the background fertility range for this species and strain and is considered not to be related to treatment.

The mean number of corpora lutea gravidatis was similar in all groups.

At 1000 mg/kg bw/day there was a reduction in the mean number of implantation sites when compared to Controls. As the corpora lutea counts at 1000 mg/kg bw/day are comparable to Controls this indicates that the process of ovulating is unaffected, although, somewhere between ovulation and implantation a loss of viable implantations occurred.

At 1000 mg/kg bw/day there was also a notable reduction in litter size throughout lactation. Compared to Controls, the group mean number of pups born and the number of live pups on Day 0 of lactation was reduced by 14%, rising to 17% reduction on Day 1 of lactation and 28% reduction on Day 4 of lactation.

ORGAN WEIGHTS (PARENTAL ANIMALS)
At 330 mg/kg bw/day and above, a dose related increase in thyroid weight was observed for males, when compared to Controls. Group mean thyroid weight increased by 47% at 330 mg/kg bw/day and 86% at 1000 mg/kg bw/day, compared to the control group mean thyroid weight. At 110 mg/kg bw/day there was an apparent slight increase in group mean thyroid weight when compared to Control. However when looking at the individual data only one male has a thyroid weight above the weight range observed in the Control animals. As all other males in this group had a thyroid weight similar to Control, the slight increase in thyroid weight in this one animal could not be positively attributed to treatment. At 330 mg/kg bw/day and above, a dose related increase in thyroid weight was observed for females, when compared to Controls. Group mean thyroid weight increased by 58% at 330 mg/kg bw/day and 88% at 1000 mg/kg bw/day, compared to the control group mean thyroid weight. Administration of Ammonium Perrhenate at 1000 mg/kg bw/day was associated with the following additional organ weight differences in males: thymus (decrease), lung (decrease), heart (decrease), kidney (decrease) and spleen (increase). No other test item-related organ weight changes were noted. There were other isolated organ weight values that were different from their respective controls. There were, however, no patterns, trends, or correlating data to suggest these values were toxicologically relevant. Thus, other organ weight differences observed were considered incidental and/or related to difference of sexual maturity and unrelated to administration of Ammonium Perrhenate.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Treatment at 1000 mg/kg bw/day in both sexes was associated with follicular cell hypertrophy in the thyroid, decreased cellularity and congestion/haemorrhaging of the bone marrow (femur, sternum and rib) and increased cellularity and macrophages in the red pulp of the spleen. Treatment at 1000 mg/kg bw/day was also associated with pituicyte hypertrophy of the pituitary in males only. The follicular cell hypertrophy in the thyroid was considered related to higher thyroid weights in high-dose animals. The increase in macrophages in the red pulp was considered to be related to the higher spleen weights observed in males. There were no histology findings that could be related to the lower weights observed in the thymus, heart, lungs and kidneys of the high-dose males. There were two females at 1000 mg/kg bw/day with atrophy of the thymus compared to 1 in Controls. The stresses endured during parturition can cause effects on the thymus and the lack of supporting organ weight effects suggest that this slight increase in incidence of thymus atrophy cannot be positively related to treatment. Other microscopic findings observed were considered incidental, of the nature commonly observed in this strain and age of rats, and/or were of similar incidence and severity in control and treated animals and, therefore, were considered unrelated to administration of Ammonium Perrhenate.

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

110 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: see 'Remark'

Remarks on result:

other: Generation not specified (migrated information)

Results: F1 generation

General toxicity (F1)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Clinical signs were observed at 1000 mg/kg bw/day

Mortality / viability:

mortality observed, treatment-related

Description (incidence and severity):

Decrease in pup viability was reported at 330 and 1000 mg/kg bw/day, when compared to Controls

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Possible mean pup weight lower than expected.

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Details on results (F1)

VIABILITY (OFFSPRING)
At 1000 mg/kg bw/day there was a reduction in the birth index, when compared to Controls. A reduced birth index indicates that there is an increase in embryo-foetal deaths in utero, when compared to Controls.

The live birth index was similar in all groups.

At 330 and 1000 mg/kg bw/day there was a notable decrease in pup viability, when compared to Controls. Viability index in Control was 99%, compared to 73% at 330 mg/kg bw/day and 84 % at 1000 mg/kg bw/day. Although the pup survival does not appear to decrease in a dose related manner, at 1000 mg/kg bw/day there was an increase in pre- and post-implantation loss meaning a reduced number of pups surviving to birth. At 330 mg/kg bw/day there were a higher number of pups surviving to birth. However, it is shortly after birth that a decline in pup survival was seen. Two dams at 330 mg/kg bw/day incurred a total litter loss.

CLINICAL SIGNS (OFFSPRING)
At 1000 mg/kg bw/day there was an increase in litters with bruised/discoloured pups, when compared to Controls. Five dams at 1000 mg/kg bw/day had pups with bruising/red patches/pale or dark skin compared to none in Controls. There was also a slight increase in litters with pups outside the nest and cold to touch, when compared to Controls.

The type and distribution of all other pup observations were considered to be typical of preweanlings and considered not related to treatment with Ammonium Perrhenate.

BODY WEIGHT (OFFSPRING)
At 1000 mg/kg bw/day there is an apparent decrease in the group mean litter weight compared to Controls. At this dose level there is also a reduction in litter size throughout lactation, however the mean of litter mean pup weight is similar to Controls. Due to decreased inter-litter competition for milk smaller litters are normally associated with increased pup weight; however here the mean of litter mean pup weight remains similar to Controls even though there is a notable reduction in litter size throughout lactation. Although the mean of litter mean pup weight may appear comparable to Controls, it cannot be discounted that these weights are lower than would be expected in litters of this size.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

Group Mean Duration of Gestation and Overall Litter Performance

	Dose Level (mg/kg/day)
	0	110	330	1000
Number Pregnant	10	10	9	8
Duration of Gestation (Days)
21	2	3	2	2
22	6	6	7	5
23	1	0	0	1
Mean Duration	21.9	21.7	21.8	21.9
Number of females producing a live litter	10	9	9	8
Gestation index as %	100	90	100	100
Mean number of implant sites^aper pregnancy ± standard deviation	15.2 ± 1.3	16.2 ± 3.3	15.9 ± 2.6	14.0 ± 1.4
Mean number of corpora lutea sites^aper pregnancy ± standard deviation	16.6 ± 2.2	18.4 ± 4.6	18.0 ± 3.1	17.4 ± 2.3
Mean total number of pups born^aper litter	14.1 ± 1.6	15.7 ± 3.8	14.7 ± 3.0	12.1 ± 2.0
Mean number of live pups^aper litter ± standard deviation:
Day 0 of lactation	13.9 ± 1.7	15.2 ± 3.5	14.6 ± 3.3	12.0 ± 2.1
Day 1 of lactation	13.8 ± 1.6	14.8 ± 3.3	13.6 ± 2.2	11.4 ± 1.8
Day 4 of lactation	13.7 ± 1.5	14.7 ± 3.3	13.4 ± 2.2	9.8 ± 2.4
Total number of males^a,bon Day 1 of lactation (%)	67 (54)	63 (47)	49 (52)	47 (60)
Total number of females^a,bon Day 1 of lactation (%)	57 (46)	70 (53)	46 (48)	31 (40)

a = Excludes litters where all pups died

b = Excludes litters with mis-counted pups

Group Mean Survival Indices

		Dose Level (mg/kg/day)
		0	110	330	1000
Birth Index	Mean Litter Index (%)	93	96	93	87
	Number Losing >2 pups	2	0	0	4
	Number of Litters	9	9	9	8
Live Birth Index	Mean Litter Index (%)	98	98	99	99
	Number Losing >1 pup	0	1	0	0
	Number of Litters	9	9	9	8
Viability Index Days 0-4	Mean Litter Index (%)	99	97	73	84
	Number Losing >3 pups	0	0	3	2
	Number of Litters	9	9	9	8

 

Group Mean Litter and Pup Weight (g)± Standard Deviation

Day of Lactation	Dose Level (mg/kg/day)
	0	110	330	1000
LITTER
Day 1	94 ± 13	93 ± 15	89 ± 14	72 ± 7
Day 4	137 ± 15	137 ± 19	131 ± 19	98 ± 24
Mean of Litter Mean Pup Weight
MALES
Day 1	7.0 ± 0.4	6.6 ± 0.9	6.9 ± 1.3	6.8 ± 0.8
Day 4	10.2 ± 0.7	9.9 ± 1.7	10.2 ± 2.0	10.4 ± 1.3
FEMALES
Day 1	6.6 ± 0.5	6.3 ± 1.0	6.6 ± 1.5	6.3 ± 0.9
Day 4	9.8 ± 0.7	9.5 ± 2.0	9.8 ± 2.2	9.7 ± 1.3

Applicant's summary and conclusion

Conclusions:

A no-observed-adverse-effect level (NOAEL) of 110 mg/kg bw/day was found for both repeated dose toxicity and reproductive toxicity/developmental toxicity screening endpoints when groups of male and female rats were given ammonium perrhenate by oral gavage. Males were treated for 2 weeks prior to mating, then through mating, until the day prior to necropsy (approximately 4 weeks of treatment). Females were treated for 2 weeks prior to mating, then through mating, gestation and until at least day 4 of lactation (approximately 6 weeks of treatment).

Executive summary:

A combined repeated dose toxicity study with reproduction/developmental toxicity screening test (OECD TG422) was conducted with ammonium perrhenate by oral gavage in rats.

Sprague-Dawley rats were randomised into 3 test groups (given 110, 330 or 1000 mg/kg bw/day) and one Control group, each containing 10 males and 10 females. The males were treated for 2 weeks prior to mating, then through mating, until the day prior to necropsy (ca 4 weeks of treatment). Females were treated for 2 weeks prior to mating, then through mating, gestation and until at least Day 4 of lactation (ca 6 weeks of treatment). The following parameters and end points were evaluated: clinical signs, body weights, body weight changes, food consumption, ophthalmology, detailed functional tests and observations, clinical pathology parameters (haematology, coagulation and clinical chemistry), gross necropsy findings, organ weights, and histopathological examinations, mating and pregnancy performance, fertility, maternal care and pup performance (litter survival and pup weights).

Treatment with Ammonium Perrhenate at 1000 mg/kg bw/day was associated with an increase in the incidence and severity of clinical observations along with a decrease in group mean body weight gain and food consumption performance (during gestation and lactation only for females). Treatment at this level also resulted in the premature death of 2 animals and effects on several clinical chemistry parameters and circulating red blood cell parameters. At necropsy an increase in the incidence of enlarged thyroid glands and mandibular lymph nodes was noted along with several organ weight effects; thyroid (increase), thymus (decrease in males), heart (decrease in males), lung (decrease in males) kidney (decrease in males) and spleen (increase in males). Microscopic findings were noted in the thyroid (follicular cell hypertrophy), pituitary gland of males (pituicyte hypertrophy), bone marrow (decreased cellularity and congestion/haemorrhage) and the spleen (increased cellularity, macrophages in the red pulp).

At 1000 mg/kg bw/day in females, several reproductive endpoints were affected including reduced implantation sites, reduced birth index, decreased litter size, and decreased pup viability over Days 1-4 of lactation and increased bruising /discolouration of pups.

Treatment at 330 mg/kg bw/day was associated with an increase in thyroid weight in both sexes and a decrease in pup viability over Days 1-4 of lactation, including two dams with a total litter loss. A slight increased incidence of ploughing and excess salivation (males only) was also noted at this dose level.

Treatment at 110 mg/kg bw/day revealed no significant changes in any of the parameters assessed that were considered to be indicative of a reaction to treatment. Overall, under the conditions of this study, a No-Observed-Adverse-Effect Level (NOAEL) was considered to be 110 mg/kg bw/day in both males and females for repeated dose toxicity and reproductive toxicity/developmental toxicity endpoints.