Calcium magnesium dihydroxide oxide

Health surveillance data

Administrative data

Endpoint:

health surveillance data

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

supporting study

Study period:

no data available

Reliability:

other: high

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Well-documented study on Ca supplementation to pregnant women to increase foetal bone mineralisation. Under physiological conditions, the hydroxyl-ions released from lime following oral adminstration have been neutralised in the GI tract and are therefore not relevant for consideration of systemic toxicity. Therefore for assessment of any systemic effects of lime following administration via the oral route, the calcium ion Ca2+ is the chemical species of interest. In the current study, calcium was supplemented to humans in the form of calcium carbonate. The carbonate ion is released as CO2 following reaction with gastric juice and is therefore toxicologically not relevant. The objective of the study was the evaluation of any effects of calcium. In view of the the limited relevance of the anionic counter-ions discussed here, calcium released both from calcium hydroxide and calcium carbonate can be considered as structurally equivalent, and the results of the study can be used by read-across.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Maternal calcium supplementation and fetal bone mineralization

Author:

Koo, W.W.K.; et al.

Year:

1999

Bibliographic source:

Obstetrics Gynecology, Vol. 94, No. 4, 577-582

Materials and methods

Study type:

medical monitoring

Endpoint addressed:

developmental toxicity / teratogenicity

Test guideline

Qualifier:

no guideline available

Principles of method if other than guideline:

Prospective double-blind, randomised, controlled trial of calcium supplementation during pregnancy.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Calcium carbonate

EC Number:

207-439-9

EC Name:

Calcium carbonate

Cas Number:

471-34-1

Molecular formula:

CH2O3.Ca

IUPAC Name:

calcium carbonate

Details on test material:

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

Method

Type of population:

general

Ethical approval:

not specified

Details on study design:

Healthy women (19-20 years of age) with early ultrasound confirmation of dates and singleton pregnancies were enrolled in a double-masked study and randomised before 22 weeks of gestation to 2 g calcium per day or placebo until delivery (128 women per group). The calcium tablets contained 500 mg of elemental Ca as CaCO3. Maternal dietary intake at randomisation and at 32-33 weeks gestation was recorded with 24-hour dietary recalls. Dual-energy X-ray absorptiometry measurements of the whole body and lumbar spine of the neonates were performed before hospital delivery.

Results and discussion

Results:

The infants of all women had dual-energy X-ray absorptiometry measurements during the first week of life. There were no significant differences between the treatment groups in gestational age, birth weight, or length of the infants or in the total-body or lumbar spine bone mineral content.
However, when bone mineral content was analyzed by treatment group quintiles of maternal Ca intake, total-body bone mineral content was significantly greater in infants born to calcium-supplemented mothers in the lowest quintile of dietary Ca intake (less than 600 mg/day). The effect of calcium supplementation remained significant after adjustment for maternal age and maternal body mass index and after normalisation for skeletal area and body length of the infant.

Applicant's summary and conclusion

Conclusions:

The results indicate that maternal calcium supplementation of 2 g per day during the 2nd and 3rd trimester can increase foetal bone mineralisation in women with lower dietary calcium intake.