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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
fertility, other
Remarks:
based on test type (migrated information)
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
Study conducted only on female rats. Reproductive toxicity indicators included estrogen, progesterone and prolactin receptors, luteinizing hormone, progesterone, and follicle-stimulating hormone serum concentrations.
Justification for type of information:
REPORTING FORMAT FOR THE CATEGORY APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH: The hypothesis is that properties are likely to be similar or follow a similar pattern because of the presence of a common metal ion, in this case tungstate.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES):
Source: Sodium tungstate
Target: Tungsten Carbide

3. CATEGORY APPROACH JUSTIFICATION: See Annex 1 in CSR

4. DATA MATRIX: See Annex 1 in CSR
Cross-reference
Reason / purpose:
read-across: supporting information

Data source

Reference
Reference Type:
publication
Title:
Tungstate administration improves the sexual and reproductive function in female rats with streptozotocin-induced diabetes
Author:
Ballester J, Munoz MC, Dominguez J, Palomo MJ, Rivera M, Rigau T, Guinovart JJ, ad Rodriguez-Gil JE
Year:
2007
Bibliographic source:
Human Reproduction Vol.22, No.8 pp. 2128–2135, 2007

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Deviations:
yes
GLP compliance:
not specified
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Animals were given a solution of 2 mg/mL sodium tungstate in 0.9% NaCl.

Test animals

Species:
rat
Strain:
Wistar
Sex:
male
Details on test animals and environmental conditions:
Adult female Wistar rats (200 g) were kept under a constant 12-hour light-dark cycle and were allowed to eat and drink ad libitum.

Administration / exposure

Route of administration:
oral: drinking water
Vehicle:
other: 0.9% NaCl
Details on exposure:
The treatment was carried out for 12-weeks. During this period, glycemia and body weight were measured regularly.
Details on mating procedure:
To evaluate reproductive performance, after 10 weeks of treatment, individual females were placed in a cage with one healthy adult male (body weight: 250 g). The animals were kept together overnight, and then separated the following morning. Immediately after each separation, a vaginal examination and scrape were carried out to determine if sexual intercourse had occurred. When intercourse was positive (presence of a vaginal tap and/or spermatozoa), the night/day routine was discontinued and the female was housed individually during the estimated period of gestation. When females showed no sexual contact with the male during 9 consecutive days, they were not used for further mating and were labelled ‘unable’, whereas those that showed sexual activity were labelled ‘able’.
Analytical verification of doses or concentrations:
not specified
Duration of treatment / exposure:
12-weeks
Frequency of treatment:
Daily via drinking water
Doses / concentrations
Dose / conc.:
2 000 mg/L drinking water
Remarks:

nominal in water
No. of animals per sex per dose:
24 female rats per group.
Control animals:
yes, concurrent vehicle
Details on study design:
All the animals were anesthetized with diethyl ether and sacrificed by decapitation.

Examinations

Parental animals: Observations and examinations:
- Histological analyses of ovaries
- Wester blot analyses for estrogen receptor, progesterone receptor, insulin receptor and FSH receptor.
Litter observations:
At parturition, litter size was determined
Postmortem examinations (parental animals):
Blood was collected immediately to measure serum parameters. All the animals were then anesthetized with diethyl ether and killed by decapitation. Ovaries horns were prepared in two ways. First, part of the tissues were immediately fixed in 3% formaldehyde in a buffer solution containing 54 mM NaH2PO4 and 28 mM Na2HPO4 (pH 7.4) at 48C (buffered formaldehyde). This material can be stored for up to 5 weeks. These tissues were used for optical microscope histology. The rest of the tissues were immediately frozen in liquid N2 and stored at 2908C until Western blot and semi-quantitative RT–PCR analyses were performed.
Statistics:
All values are means + SEM. Statistical comparisons of the means were performed by analysis of variance, followed by the Student– Neumann–Keuls test. This test makes multiple pairwise comparisons, where the cut-off point to which comparisons are made changes between them. Thus, this methodology shows greater sensitivity than other similar multiple pairwise comparison tests, such as the Student’s t-test. A P-value of (0.05 was considered to be statistically significant.
Reproductive indices:
The reproductive performance of the rats was measured as the proportion of ‘able’ females to the total number tested (the percentage of positive vaginal scrapes, i.e. those with presence of spermatozoa, with respect to the total number of vaginal scrapes performed in one experimental group). This parameter was named as ‘mating index’. The number of vaginal scrapes varied depending on the time required by animals to show positive intercourse. Furthermore, we also calculated the percentage of parturitions with respect to the number of positive scrapes. This parameter was named ‘fertility’. These definitions do not necessarily coincide with the common definitions for mating index, fertility and prolificacy published elsewhere.
Offspring viability indices:
The mean litter size was also calculated and was defined as ‘prolificacy’. These definitions do not necessarily coincide with the common definitions for mating index, fertility and prolificacy published elsewhere.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Mortality:
no mortality observed
Description (incidence):
At the end of the experiment, all the rats in the tugstate treated healthy (TH) rats were alive.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Tungstate treatment also caused a decrease in the body weight gain of healthy rats
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Tungstate treatment did not modify daily food intake in rats.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
Tungstate treatment did not modify daily water consumption in healthy rats
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
no effects observed
Description (incidence and severity):
Tungstate treatment did not modify serum levels of glucose, ALT activity, insulin, progesterone, FSH and LH in healthy rats
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
Histological analyses of ovaries did not show evident differences between groups. Thus, active ovaries showing evolutive follicles, corpora lutea and follicular glands were detected in all groups. Ovaries were generally covered by a significant amount of adipose tissue.
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed
Description (incidence and severity):
- Tungstate did not significantly affect LH receptor mRNA content in healthy rats
- Tungstate slightly decreases western blot band intensity of GLUT 3 hexose expression in ovaries of healthy rats.
- No differences in the expression of the estrogen receptor in tungstate treated healthy rats.
- Tungstate does not affect the amount of ovarian prolactin receptor mRNA.

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Description (incidence and severity):
Tungstate treatment did not modify Leydig cell function in healthy rats
Reproductive performance:
no effects observed
Description (incidence and severity):
Tungstate administration did not alter the reproductive performance of healthy female rats.

Details on results (P0)

- All the rats in the conrol and tretated tungstate group survived.
- Tungstate exposed rats have lower body weight gain than control animals.
- Tungsten treatment had no effect on serum glucose, insulin, alanine aminotransferase, luteinizing hormone, progesterone, and follicle-stimulating hormone concentrations.
- Tungstate treatment did not affect any reproductive parameter in healthy rats.
- Tungsten treatment does not affect the expression of estrogen, progesterone and prolactin receptors as determined by western blotting.

Effect levels (P0)

Key result
Dose descriptor:
NOAEL
Effect level:
> 2 000 mg/L drinking water
Based on:
test mat.
Sex:
female
Basis for effect level:
reproductive performance

Results: F1 generation

General toxicity (F1)

Clinical signs:
not examined
Mortality / viability:
not examined
Body weight and weight changes:
not examined
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Histopathological findings:
not examined
Other effects:
no effects observed
Description (incidence and severity):
Tungsten treatment did not alter prolifacy (litter size)

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Overall reproductive toxicity

Key result
Reproductive effects observed:
no

Applicant's summary and conclusion

Conclusions:
Oral administration (2 mg/ml in drinking water) of sodium tungstate to adult female for 12 weeks did not show hypoglycemia, did not alter the reproductive performance of healthy females or any alteration in estrogen, progesterone and prolactin receptors. In adddition, tungsten treatment had no effect on luteinizing hormone, progesterone, and follicle-stimulating hormone serum concentrations. Tungstate orally did not alter the reproductive performance of healthy females.
Executive summary:

No fertility, reproductive, or developmental toxicity data of sufficient quality are available for tungsten carbide (target substance). However, reproductive toxicity data are available for sodium tungstate (source substance), which will be used for reading across. Due to lower water solubility and lower toxicity for the target substance compared to the source substance, the resulting read across from the source substance to the target substance is appropriate as a conservative estimate of potential toxicity for this endpoint. In addition, read across is appropriate because the classification and labelling is more protective for the source substance than the target substance, the PBT/vPvB profile is the same, and the dose descriptors are, or are expected to be, lower for the source substance. For more details, refer to the read-across category approach included in the Category section of this IUCLID submission and/or as an Annex in the CSR.