Magnesium chloride

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: No information on analytical verification

Data source

Reference

Reference Type:

publication

Title:

Teratogenicity Study of Magnesium Chloride Hexahydrate in Rats

Author:

Usami M., Sakemi K., Tsuda M. and Ohno Y.

Year:

1996

Bibliographic source:

Bull. Natl. Inst. Health Sci., 114, 16-20

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

magnesium chloride hexahydrate

IUPAC Name:

magnesium chloride hexahydrate

Constituent 2

Reference substance name:

7791-18-6

Cas Number:

7791-18-6

IUPAC Name:

7791-18-6

Details on test material:

MgCl2·6H2O, Food Additive Quality Magnesium Chloride S, ex Tomita Pharmaceutical Co., Ltd.
A minimum purity of 95%.

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

Wistar rats obtained from Nippon Charles River, Kanagawa, Japan were used.
The nulliparous female and male animals were 10 and 11 weeks old, respectively.
Pregnant animals were kept individually in aluminum cages.

The animals were maintained under controlled environmental conditions of 25 °C ± 2 °C temperature, 55 ± 5% relative humidity, and 12-hours light-dark cycle, (light phase: 6:00 ~ 18:00) and received solid food and tap water ad libitum.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

The concentration of the test substance solution was set at 5 mL/kg/day at each dosage level.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data

Details on mating procedure:

Nulliparous females were mated overnight with males. Females revealing spermatozoa in the vaginal smear in the following morning were considered to be pregnant and used in the experiment. The day, when sperms were found in the vaginal smear, was designated as day 0 of gestation.

Duration of treatment / exposure:

From day 6 through 15 of pregnancy (10 days)

Frequency of treatment:

By gavage (one by day)

Duration of test:

20 day of gestation

No. of animals per sex per dose:

22

Control animals:

yes, concurrent vehicle

Details on study design:

The pregnant rats were sacrificed on day 20 of pregnancy and their fetuses were examined for malformation.
For the control group, 5 mL/kg/day distilled water was administered to the animals in the same manner as for the dose groups.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATION: YES
The general condition of the animals was observed every day.

BODYWEIGHT: Yes
Body weight was measured at day 0, 1, 3, 6, 9, 12, 15, and 17 of pregnancy.

FOOD INTAKE: YES
Food intake was measured at day 0, 1, 3, 6, 9, 12, 15, and 17 of pregnancy.

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: No data
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Fetal examinations:

- Weight : Yes all per litter
- External examinations: Yes all per litter
- Soft tissue examinations: Yes all per litter according to a gross sectioning technique (abdominal cavity) and a microdissection technique (thoracic space)
- Skeletal examinations: Yes half per litter (prepared for staining with alizarin red)
- Head examinations: Yes half per litter (according to a gross sectioning technique)

Statistics:

Pregnant animals or one uterus were taken as sample units. For frequency data, Fisher's direct exact probability test was applied to test the significance of differences between the control group and the magnesium chloride hexahydrate groups. With regard to observation data, statistical analysis and Scheffé's method were applied when no variance differences between the groups were found according to Bartlett's equal variance test. For measured data and count data with variance differences between the groups, we used the H test (Kruskal-Wallis test) and Scheffé's method.

Indices:

No data

Historical control data:

No data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:not examined

Details on maternal toxic effects:
There were no differences between the groups with regard to general condition and death. Furthermore, no significant differences between the control group and magnesium chloride hexahydrate groups were observed with respect to body weight and food consumption.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

> 800 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
Regarding the number of corpora lutea, number of implants, number of living fetuses, sex ratio, fetal weight and mortality of implants/fetuses, no significant differences between control group and the magnesium chloride hexahydrate groups were observed.
One to 4 fetuses with gross malformations were found in each group. However, regarding the incidence rate, there was no significant difference between control group and magnesium chloride hexahydrate groups.
In the 800 mg/kg/day group, one fetus had skeleton malformations, however, with regard to the incidence rate; there was no significant difference between control group and the magnesium chloride hexahydrate groups. Furthermore, no significant differences between control group and magnesium chloride hexahydrate groups were observed as far as the incidence rate of skeletal variations is concerned. Regarding the incidence rate of fetuses with lumbar rib and additional rib bones, there were no significant differences. No significant differences were found in the number of ossification centers, metacarpal and metatarsal bones as well as sacral and tail vertebrae. The aforementioned numbers were examined as indicators for the progress of ossification.
Four to 6 fetuses in each group showed malformations, however, no significant difference were observed between control group and magnesium chloride hexahydrate groups.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

> 800 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Fetal growth in pregnant rats treated with MgCl2, 6H2O

	Dose (mg/kg/day)
	Control	200	400	800
Nb of litters	22	22	22	22
Nb of corpera lutea	373	370	361	362
Mean +/- SD	17.0 +/-1.6	16.8 +/-2.2	16.4 +/-2.1	16.5 +/-1.5
Nb of implants	364	340	345	345
Mean +/- SD	16.5 +/-1.7	15.5 +/-3.2	15.7 +/-1.9	15.7 +/-1.8
Implantation rate (%)	97.7 +/-4.5	91.4 +/-12.2	95.9 +/-6.6	95.4 +/-8.3
Nb of live fetuses	346	326	324	332
Mean +/- SD	15.7 +/-1.5	14.8 +/-3.5	14.7 +/-1.8	15.1 +/-1.8
Sex ratio male/female	1.28	1.15	1.23	1.38
Fetal weight (g)
Male	3.95 +/-0.22	3.98 +/-0.29	3.87+/-0.21	3.98 +/-0.22
Female	3.73 +/-0.25	3.75 +/-0.23	3.72 +/-0.20	3.81 +/-0.17
Nb of dead implants	18	14	21	13
Early death	18	14	21	13
Late death	0	0	0	0
Mortality (%)	4.8 +/-4.6	4.8 +/-5.8	5.9 +/-6.1	3.6 +/-5.7

 Mean +/- SD is shown

Gross malformation in the fetuses from pregnant rats treated with MgCl2, 6H2O

	Dose (mg/kg/day)
	Control	200	400	800
Nb of litters	22	22	22	22
Nb of fetuses examined	346	326	324	332
Nb of litters with malformed fetuses	3	1	3	1
Nb of fetuses with malformation	3	1	4	1

Skeletal variations the fetuses from pregnant rats treated with MgCl2, 6H2O

	Dose (mg/kg/day)
	Control	200	400	800
Nb of litters	22	22	22	22
Nb of fetuses examined	174	168	165	165
Nb of fetuses with malformation	0	0	0	1
Nb of fetuses with variation	76	71	89	84
Lumbar rib	14	13	18	16

Visceral variations the fetuses from pregnant rats treated with MgCl2, 6H2O

	Dose (mg/kg/day)
	Control	200	400	800
Nb of litters	22	22	22	22
Nb of fetuses examined	170	157	159	166
Nb of litters with malformed fetuses	4	4	5	4
Nb of fetuses with malformation	5	4	6	5

Applicant's summary and conclusion

Conclusions:

under the condition of this study, It is obvious that magnesium chloride hexahydrate has no teratogenic effect when administered orally to rats from day 6 through 5 of pregancy at dose 800 mg/kg/day.

Executive summary:

Teratogenicity of magnesium chloride hexahydrate (MgCl2·6 H2O) was examined in rats. Magnesium chloride hexahydrate dissolved in distilled water was given to pregnant Wistar rats by gavage once a day from day 6 through 15 of pregnancy at doses of 0, 200, 400 and 800 mg/kg/day. The pregnant rats were sacrificed on day 20 of pregnancy and their fetuses were examined for malformation. Magnesium chloride hexahydrate caused no increased incidences of fetal malformation, and no toxic signs in the pregnant rats and the fetuses.

It was concluded that magnesium chloride hexahydrate has not teratogenicity in rats when given by gavage. The no observed adverse effect level was estimated to be over 800 mg/kg/day for both pregnant rats and rat fetuses.