Registration Dossier

Toxicological information

Toxicity to reproduction

Currently viewing:

Administrative data

Endpoint:
toxicity to reproduction
Remarks:
other: Continuous mating for 80 days (up to 4 litters)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
no data available
Reliability:
2 (reliable with restrictions)

Data source

Reference
Reference Type:
publication
Title:
The effects of additions of calcium carbonate to the diet of breeding mice. 1. Effects on reproduction and on the heart and thymus weights of the weanlings
Author:
Richards; M.B.; Greig, W.A.
Year:
1952
Bibliographic source:
British Journal of Nutrition 6: 265-280

Materials and methods

Test guideline
Qualifier:
no guideline available
Principles of method if other than guideline:
The effect of the different levels of CaCO3 on the reproductive performance of mice and the development of the offspring (as judged by the number of young born and reared as well as by the mortality observed during weaning) was tested. Two experiments were conducted.
GLP compliance:
no
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Calcium carbonate
- Physical state: solid
No further details are given.

Test animals

Species:
mouse
Strain:
Swiss
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: (P) 7 weeks
- Diet: ad libitum, each breeding female was given basal diet up to the age of 7 weeks, and was then given the appropriate experimental diet a week before being mated
- Water: ad libitum, supplemented with fresh whole milk to the mated pairs of adult mice
No further details are given.

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
DIET PREPARATION
- Mixing appropriate amounts with basal diet: Three levels of CaCO3 were added to a slightly modified Sherman B diet (diet 2). Diet 2 (basal diet) consisted of ground whole wheat 66 %, dried whole milk 33
% and NaCl 1 %.
The basal diet 70 was formed drom diet 2 by substituting 6 g maize starch for 6 g wheat, thus reducing the vitamin B content without increasing the protein.
The basal diet 74 was derived from diet 2 by substituting 6 g casein for 6 g wheat, thus reducing the vitamin B content but this time increasing the protein. The basal diet 78 was derived from diet 2 by
substituting 5 g casein.
Diets were completed by the addition of CaCO3 at differnt rates.
No further details are given.
Details on mating procedure:
Females were mated with a male of the same age. Mating of litter-mate brothers and sisters was avoided. The method of continuous monogamous mating was used.
- M/F ratio per cage: 1/1
- Length of cohabitation: 80 days
- Proof of pregnancy: no data
- Further matings after two unsuccessful attempts: no data
- After successful mating each pregnant female was caged (how): no data
- Any other deviations from standard protocol: Parental reproductive parameters (oestrus cyclicity, sperm parameters) were not explicitly investigated. Also see below for any other parameters not addressed.
This is not a guideline study, pre-dating any official test guidelines.
Analytical verification of doses or concentrations:
no
Details on analytical verification of doses or concentrations:
No details available
Duration of treatment / exposure:
Continuously until sacrifice (the observations were ended by killing the litters on weaning at 21 days of age.)
Frequency of treatment:
Continuously
Details on study schedule:
No details are given.
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0.5 g/100g
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
1.0 g/100g
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
2.0 g/100g
Basis:
nominal in diet
No. of animals per sex per dose:
4 female mice were allocated to each group in Experiment I
8 female mice were allocated to each group in Experiment II
Control animals:
yes
Details on study design:
No further details are given.
Positive control:
No positive control substance was tested.

Examinations

Parental animals: Observations and examinations:
No details if observation of the parental animals were made are reported.
Oestrous cyclicity (parental animals):
No data available
Sperm parameters (parental animals):
No data available
Litter observations:
The effect of the diets on reproduction was judged by the number and weight of the young reared in a given period.
In Experiment I the females were maintained on the diets long enough to rear any litters that had been conceived.
In Experiment II sufficient time was allowed for rearing only two litters.
The observations were ended by killing the litters on weaning at 21 days of age. Post mortem examinations were made.
The heart and thymus weights were recorded.
Postmortem examinations (parental animals):
SACRIFICE
- Maternal animals
GROSS NECROPSY
- Gross necropsy consisted of internal examinations including the livers, hearts thymus glands and spleen.
HISTOPATHOLOGY / ORGAN WEIGHTS
The heart and thymus weights were recorded.
Postmortem examinations (offspring):
SACRIFICE
- Some of the weanlings were killed at 21 days of age
- These animals were subjected to postmortem examinations
GROSS NECROPSY
- Gross necropsy consisted of internal examinations including the livers, hearts, thymus glands and spleen
HISTOPATHOLOGY / ORGAN WEIGTHS
The heart and thymus weights of the young mice were recoded.
Statistics:
no data
Reproductive indices:
no data available
Offspring viability indices:
no data available

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Organ weight findings including organ / body weight ratios:
effects observed, treatment-related

Details on results (P0)

ORGAN WEIGHTS (PARENTAL ANIMALS)
The high Ca level also caused a significant increase in the absolute and relative heart weights of the mothers.
No further details are given.

Effect levels (P0)

open allclose all
Dose descriptor:
LOAEL
Effect level:
2 other: % CaCO3 in diet
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Remarks on result:
other: Generation: young weaned animals (migrated information)
Dose descriptor:
LOAEL
Effect level:
2 other: %CaCO3 in diet
Sex:
female
Basis for effect level:
other: The high Ca level also caused a significant increase in the absolute and relative heart weights of the mothers. Based on these changes, the LOAEL for maternal toxicity is established at the dose level of 2.0 % CaCO3.

Results: F1 generation

General toxicity (F1)

Mortality / viability:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Sexual maturation:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related

Details on results (F1)

VIABILITY AND BODY WEIGHT (OFFSPRING)
On all diets the highest addition of calcium carbonate, which gave a Ca intake of 1.1 % and a Ca:P ratio of approximately 2.3, significantly lowered the number and total weight of young weaned and increased the number and proportion of deaths. There was also some decrease in the number of births.
ORGAN WEIGHTS (OFFSPRING)
Both absolutely and relatively to body-weight the heart weights of the weanlings were significantly increased by Ca and decreased by Fe, whereas thymus weights were decreased by Ca and increased by Fe.
Although the percentage of dry matter in the hearts of the weanlings was significantly lowered by the higher level of Ca, there was a marked increase in the absolute weight of heart dry matter at this level, indicating the presence of a cardiac hypertrophy.
No further details are given.

Overall reproductive toxicity

Reproductive effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
In all diets, the highest level of CaCO3, 1.1 % Ca contents in food and a Ca:P ratio of approx. 2.3, significantly lowered the number and total weight of young weaned and increased the number and
proportion of deaths. There was also some decrease in the number of births. Thus, this dose level of 2 % CaCO3 (1.1 % Ca) is considered as LOAEL for effects on reproductive performance.
The high Ca level also caused a significant increase in the absolute and relative heart weights of the mothers. Based on these changes, the LOAEL for maternal toxicity is established at the dose level of 2.0 % CaCO3. However, daily doses could not be calculated for lack of data on daily food intake. Therefore, determination of a proper NOAEL is not possible.