Registration Dossier

Toxicological information

Developmental toxicity / teratogenicity

Currently viewing:

Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1982 - 1983
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study performed under GLP-like quality control. No data on purity were available. Dosing was performed from day 6 to 15 of gestation only.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1983
Report date:
1983

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
(adopted 1983)
Deviations:
no
GLP compliance:
no
Remarks:
but QAU statement included
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Calcium diethyl bis[[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate]
EC Number:
265-512-0
EC Name:
Calcium diethyl bis[[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate]
Cas Number:
65140-91-2
Molecular formula:
C17 H29 O4 P. 1/2Ca
IUPAC Name:
calcium diethyl bis[[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate]
Details on test material:
Physical appearance: solid
Storage conditions: room temperature
Purity: no data

Test animals

Species:
rat
Strain:
other: Sprague-Dawley derived Tif:RAIf (SPF) rats
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: closed breeding colony, Ciba-Geigy WST
- Age at study initiation: 2 months
- Weight at study initiation: 180-200 g
- Housing: 5 per cage in Makrolon cages
- Diet: NAFAG No. 890, ad libitum
- Water: ad libitum
- Acclimation period: day 0 to day 6 post coitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21+/-2
- Humidity (%): 55+/-10
- Photoperiod: 12 hrs dark / 12 hrs light

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
CMC (carboxymethyl cellulose)
Remarks:
0.5%
Details on exposure:
The suspension of the test material was freshly prepared daily by homogenization and stirring (magnetic stirrer), and administered at a rate of 10 mL/kg of body weight.
Details on mating procedure:
The females were mated overnight with males of proven fertility in the ratio of 1 male / 3 females. The day on which spermatozoa were found in the vaginal smear or a vaginal plug was observed, was designated as day 0 of pregnancy.
Duration of treatment / exposure:
Day 6 to day 15 of pregnancy
Frequency of treatment:
Once daily.
Duration of test:
until day 21 of gestation
Doses / concentrations
Remarks:
Doses / Concentrations:
400, 1200, 2400 mg/kg bw/day
Basis:
actual ingested
No. of animals per sex per dose:
25 pregnant rats
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:
Doses were based on results of a preliminary study, where 10 rats were dosed with vehicle or 2000 mg/kg bw test substance. The dams of the experimental group (2000 mg/kg bw) reacted to the treatment by some reduction in body-weight gain and food intake in comparison with the vehicle control. Concerning the progeny, no abnormalities were revealed by the external examination; the average weight of the foetuses of the 2000 mg/kg bw dose group was not significantly diminished in comparison with the vehicle control (Student's t test, one-tailed, observed p < 0.01).

Examinations

Maternal examinations:
During the period of treatment, general bodily condition, weight gain and symptoms were checked daily. Food consumption was noted on days 6,
1 1 , 16 and 21 of pregnancy. The average body weight gain of the females was determined on the basis of the actual body weight as well as that on the first day of treatment and at the time of necropsy, corrected by subtracting the weight of the gravid uterus.
Ovaries and uterine content:
Investigation of ovaries and uterus: mucosa and contents, including amniotic fluid and placentae as well as abortions and resorption sites.
Fetal examinations:
- Sex determination
- Careful external inspection
- Weighing
- Examination of the viscera according to the slicing technique of WILSON (J.G. Wilson and J. Warkany, eds.. The University of Chicago Press, Chicago and London, 1965, pp. 265-277). One third of the live foetuses per litter were fixed in a mixture of ethyl alcohol and formaldehyde solution to which acetic acid had been added.
- Skeletal assessment in two thirds of the foetuses per litter following clearing in potassium hydroxyde and staining with alizarine red S was carried out.
- Uterine horns showing no evident implantation sites were placed into a solution of ammonium sulfide to visualize possible haemorrhagic alterations in such sites.
Statistics:
The numbers of embryonic and/or foetal deaths (resorptions) (Chi*-test, Yates' correction, observed p > 0.01).
The male to female ratios of the foetuses (Chi* -test, Yates' correction, observed p > 0.05).
Historical control data:
Spontaneous data characteristic of the breed of rats used in the present study refer to a series of untreated controls ("historical" or cumulative control) observed over a period of 69 months (listed in the study report).

Results and discussion

Results: maternal animals

Maternal developmental toxicity

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

Details on maternal toxic effects:
Body-weight gain was comparable for the dams of all groups. Food consumption of the experimental groups, however, showed some reduction during the treatment period (from day 6 of pregnancy) in comparison with the vehicle control. Female No. 32 (400 mg/kg) died on day 6 in consequence of an intubation error. Females No. 4 (vehicle control) and No. 78 (2400 mg/kg) delivered "spontaneously" (i.e. shortly before sacrifice on day 21 p.c.) and were not taken into further consideration of data. Signs of inflammation of the liver were found in one female of the vehicle control.
The rates of implantation sites per female were comparable for all groups. The numbers of embryonic and/or foetal deaths (resorptions) were not increased at either dose. The male to female ratios of the foetuses were also comparable for all groups (Chi* -test, Yates' correction, observed p > 0.05).

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
2 400 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
2 400 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:
In comparison with the vehicle control, the average body-weight of the live foetuses was not diminished at either dose. A slight but significant increase was noted for the live foetuses of the intermediate and, at a lower extent, of the high-dose group. This finding, however, is not assumed to be of a biological relevance.
The gross and/or visceral examination of the live foetuses revealed one foetus with anasarca in the vehicle control, two foetuses from one litter with subpleural haemorrhage in the low-dose group, one foetus each displaying mandibular aplasia and partial aplasia of the lungs, respectively, in the intermediate dose and one foetus showing omphalocele in the high-dose group. These findings are considered to be of a spontaneous origin and not related to the treatment. The incidences of mandibular aplasia, omphalocele and anasarca were found to be 0.05%, 0.04% and 0.12%, respectively, in the historical control population of the breed of rats used for the present experiment.
The skeletal assessment revealed instances of irregular sternebral ossification in the dose groups and in the vehicle control. This occurrence of sternebral anomalies in all groups was not assumed to be of an experimental significance, the overall incidence of sternebral anomalies being 0.37% in the historical control. Concerning the status of skeletal maturation of the foetuses shortly before term, no delay of ossification could be found for the experimental groups in comparison with the vehicle control.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Table 1: Summarized reproduction data of the main study.

Dose group

(mg/kg d)

0

400

1200

2400

Historical control

Spontaneous deaths

0/25

0/24

0/25

0/25

0/842

Body-weight gain (%)

+10.3

+10.3

+13.0

+9.3

 

Females with deciduomata

0/25

0/24

0/25

0/25

1/842

Females with implantations

22/25

22/24

24/25

22/25

784/842

Implantations/female (mean, SD)

15.4±2.0

15.7±2.9

14.5±1.9

15.0±2.7

13.09±2.33

Females with total abortion

0

0

0

0

0/784

Females with partial abortion

0

0

0

0

2/784

Embryonal deaths (resorptions)

3.8

7.0

8.4

8.2

8.74

Foetal deaths (resorptions)

0.3

0.3

0

0.3

0.28

Dead foetuses

0

0

0

0

0.13

Number of live foetuses (males-females)

155-170

166-154

160-158

146-155

4554-4765

Percent males of live foetuses

47.7

51.9

50.3

48.5

48.9

Average weight of live foetuses (g)

5.3±0.5

5.3±0.4

5.4±0.4

5.4±0.4

5.34±0.45

 

Applicant's summary and conclusion

Conclusions:
Based on the results and under the condition chosen, the test article is considered to be not teratogenic.
Executive summary:

In a prenatal developmental toxicity study following OECD guideline 414, 25 pregnant Tif:RAIf (SPF) rats per dose group were treated daily with the test article by gavage at 400, 1200, 2400 mg/kg body weight from day 6 to 15 of gestation. Dams were killed on day 21 and fetuses removed by Caesarian section. Body-weight gain was comparable for the dams of all groups. Food consumption of the experimental groups, however, showed some reduction during the treatment period (from day 6 of pregnancy) in comparison with the vehicle control. One female of the low dose group died due to an intubation error. Females No. 4 (vehicle control) and No. 78 (2400 mg/kg) delivered "spontaneously" (i.e. shortly before sacrifice on day 21 p.c.) and were not taken into further consideration of data.

The rates of implantation sites per female were comparable for all groups. The numbers of embryonic and/or fetal deaths (resorptions) were not increased at either dose. The male to female ratios of the fetuses were also comparable for all groups. In comparison with the vehicle control, the average body-weight of the live fetuses was not diminished at either dose. A slight but significant increase was noted for the live fetuses of the intermediate and, at a lower extent, of the high-dose group. This finding, however, is not assumed to be of a biological relevance. The gross and/or visceral examination of the live fetuses revealed one fetus with anasarca in the vehicle control, two fetuses from one litter with subpleural haemorrhage in the low-dose group, one fetus each displaying mandibular aplasia and partial aplasia of the lungs, respectively, in the intermediate dose and one fetus showing omphalocele in the high-dose group. The skeletal assessment revealed instances of irregular sternebral ossification in the dose groups and in the vehicle control. Concerning the status of skeletal maturation of the fetuses shortly before term, no delay of ossification could be found for the experimental groups in comparison with the vehicle control. Based on the findings a NOAEL of 2400 mg/kg body weight (highest dose tested) was derived for maternal and developmental toxicity.