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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16Jan 1992 -02Apr 1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
Version May 1981
Deviations:
yes
Remarks:
Different exposure duration
Principles of method if other than guideline:
In this study, pregnant rats were only exposed on day 6-15 of pregnancy, whereas recent guideline recommends exposure day 5 - end of pregnancy. However, guideline from 2001: dosing only during organogenesis, not up to caesarian section.
In addition the gravid uteri and cervices are not weighed. These deviations were not considered to influence the study.
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: crystalline
Details on test material:
- Physical appearance: yellow crystalline powder
- Storage conditions: at room temperature

Test animals

Species:
rat
Strain:
other: Crl: CD®(SD) BR VAF/Plus
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River UK Limited, Kent, UK
- Age at study initiation: 8-10 weeks
- Weight at study initiation: 173-248 g
- Housing: Rats were housed five to a cage in suspended galvanised metal cages
- Diet: free access to Biosure Laboratory animal diet No.1
- Water: tap water at libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21± 3
- Humidity (%): 47 ± 3
- Air changes (per hr): not described
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Remarks:
distilled and deionised
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The highest concentration was prepared by dissolving an appropriate weight of sodium ferrocyanide in ditilled, deionised water. Lower concentrations were prepared by serial dilution of the highest concentration in distilled, deionized water. Formulations were prepared weekly and stored at 4°C in the dark when not in use.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
UV-spectroscopy was used as a method, which was also validated. Concentrations of substance in test solutions prepared for day 1 of dosing were determined. Chemical stability was determined.
Details on mating procedure:
Female rats were time mated to identified males of the same strain at Charles River and as such obtained. Day 0 = day of mating, as judged by the appearance of sperm in the vaginal smear or by the presence of a vaginal plug.
Duration of treatment / exposure:
Day 6-15 (including) of pregnancy.
Frequency of treatment:
Daily
Duration of test:
Day 1-20 of pregnancy.
No. of animals per sex per dose:
25, females only
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: In a preliminary study with less animals the highest dose (1000mg/kg/day) was shown to be well-tolerated.
- Rationale for animal assignment: Animals were weighed and assigned to four groups by computerised stratified randomisation to give approximately equal initial group mean body weights within each batch.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily observation
- Cage side observations as described in test guideline were included.

BODY WEIGHT: Yes
- Time schedule for examinations: all animals weighed on day 1, 2, 3, 6, 8, 10, 12, 14, 16, 18 and 20

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption was measured daily for each cage of animals from day 3 to weigh day commencing on day 3 and represented as group mean values (g/rat/day).

WATER CONSUMPTION: Yes
- Water consumption was measured daily for each cage of animals from Day 3 through to termination and represented as group mean values (g/rat/day).

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Rats examined for congenital abnormalities and macroscopic pathological changes in maternal organs.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:
- External examinations: Yes, all foetuses
- Foetal weight
- Soft tissue examinations: Yes: half the foetuses in each litter
- Skeletal examinations: Yes: half the foetuses in each litter
Statistics:
Significance tests, employing analysis of variance followed by an intergroup comparison with the control, were performed on several parameters. Dependent on the heterogeneity of variance between the treatment groups, parametric tests (analysis of variance followed by Williams' test) or non-parametric tests (Kruskal-Wallis followed by Shirley's test) were used to analyse the data, as appropriate. For litter data and foetal changes, the basic sample unit was the litter and, due to the preponderance of non-normal distributions, non-parametric analyses were routinely used. Where 75% or more of the values for a given variable were the same, a Fisher's exact test was performed.
Indices:
Pre implantation loss (as percentage): ((# corpora lutea -# implantations)/ # corpora lutea)x100;
Post implantation loss (as percentage): ((# implantations - # live young)/ # implantations)x 100.
Historical control data:
Recent historical control groups showed lower incidence in renal lesions than seen in the 500 and 1000 mg/kg/day groups.
No other information given on historical control data.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
Number of pregnant rats/ group did not change with treatment:
Control: 21/25
100 mg/kg/day: 22/25
500 mg/kg/day: 21/25
1000 mg/kg/day: 23/25
One total resorption in control group.

Signs
No treatment-related signs, except treatment at 1000 mg/kg/day was associated with occasional instances of post dosing salivation in 12/23 pregnant rats with greatest incidence on day 9 of pregnancy. Salivation occasionally brown stained, ceased within half an hour of dosing. No differences between pregnant rats in different groups in bodyweight change. No mortalities occurred.

Water and food consumption
An increase in water consumption was noted for all treated groups (cumulative water consumption during treatment period showed dosage-related increase in all treated groups (p<0.05). No effect on food consumption was found.

Macroscopic examination
No adverse effects of treatment were revealed

Effect levels (maternal animals)

open allclose all
Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No adverse effect of treatment was apparent, as assessed by embryofoetal loss, litter and mean foetal weight or sex ratio.
Incidence, type and distribution of malformation and skeletal anomalies and the percentage of foetuses with variant sternebrae were considered not to reflect any adverse effect of treatment.
In groups dosed with 500 or 1000 mg/kg/day a marginal but not statistically significant increase in the number of foetuses with increased dilation of the renal pelvis/ureter was found (4 and 5 foetuses from 4 and 4 litters resp.; in control group: 2 foetuses from 2 litters).

Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: developmental toxicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

The mean concentrations of sodium ferrocyanide in test solutions were all within 4% of nominal concentrations. The chemical stability of sodium ferrocyanide in aqueous solutions was confirmed during storage for 4 hours at ambient temperature and at +4 °C for 8 days. The method is confirmed to be precise and accurate.

Applicant's summary and conclusion

Conclusions:
In an OECD 414 oral developmental toxicity study , rats were dosed up to 1000 mg/kg/ day of sodium ferrocyanide via gavage, resulting in no treatment related effects and thus an NOAEL of ≥ 1000 mg/kg/day could be derived (both maternal and developmental).

Executive summary:

In a prenatal developmental toxicity study, pregnant rats were orally exposed to different dosages of sodium ferrocyanide up to 1000 mg/kg/day. The animals were exposed daily, from day 6 to (and including) day 15 of the pregnancy. Rats were sacrificed at day 20. Treatment with sodium ferrocyanide at 1000 mg/kg/day elicited occasional instances of post-dosing salivation in about half of the animals with the greatest incidence occuring after 4 days of dosing. Over the dosing period as a whole, water intake of all three groups was significantly higher than of the control value, the greatest difference being recorded at 1000 mg/kg. This effect was not considered adverse. No other treatment or dosage-related responses were observed in the dams and litter parameters appeared to be unaffected at all of the dosages investigated, as judged by in utero survival, foetal growth and morphological development. Although a small number of foetuses from the two highest dosages showed increased dilation of the renal pelvis/ ureter, this increase was marginally and not statistically significant and thus not considered to be an effect of treatment. This results in a maternal NOAEL of ≥1000 mg/kg/day and a developmental NOAEL of ≥1000 mg/kg/day.