Magnesium chloride

Endpoint summary

Description of key information

Repeated dose toxicity studies have been conducted with magnesium chloride hexahydrate via the oral route. The results have been corrected to magnesium chloride anhydrous.

The key study (OECD 422) and the supporting studies observed no oral toxicity for repeated exposure except a decrease in body weight.

The rats being the more sensitive species, the LOAEL and NOAEL, for MgCl2 anhydrous, were deduced on it except for 2 years study (only data available for mice).

NOAEL (28 days) = 466 mg/kgbw/day - rat

NOAEL (90 days) = 140 mg/kgbw/day - rat

LOAEL (90 days) = 713 mg/kgbw/day - rat 

NOAEL (2 years) = 1309 mg/kgbw/day - mice

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

chronic toxicity: oral

Remarks:

combined repeated dose and carcinogenicity

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Materials and methods well described. No information on analytic verification. Deficiencies: two levels of dose.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 453 (Combined Chronic Toxicity / Carcinogenicity Studies)

Deviations:

yes

Remarks:

Only two doses levels

GLP compliance:

not specified

Limit test:

no

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Mice, 6 weeks old, were obtained from Charles River Japan Inc, Kanagawa, Japan
Mice were housed in plastic cages (five animals/cage) containing bedding of wood chips (Beta Chip Bedding, Northeastern Products Co, NY, USA). The cages were housed in an environmentally controlled room maintained at a temperature of 20 (+/-2)°C, a relative humidity of 55 (+/-10)% and a 12-hr light/dark cycle.
The animals were kept under optimal hygienic conditions and were moved twice each week to allow cleaning of the cages and a change of bedding.
Prior to the study, the animals received a commercial diet ad lib.

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

Prior to the study, the animals received a commercial diet ad lib (Oriental M) (Oriental Yeast Co, Tokyo, Japan) MgCl2, 6H20 (98% pure) obtained from
Wako Pure Chemical Industries Ltd, Osaka, Japan, mixed with the commercial powdered diet at the appropriate concentrations.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

no data

Duration of treatment / exposure:

96 weeks and 8 weeks of post exposure period (104 weeks)

Frequency of treatment:

Daily

Remarks:

Doses / Concentrations:
0.5%
Basis:
nominal in diet

Remarks:

Doses / Concentrations:
2%
Basis:
nominal in diet

No. of animals per sex per dose:

50 animals per sex per dose

Control animals:

yes, plain diet

Details on study design:

The dietary levels of MgCl2 6H20 were selected on the basis of results from a preliminary investigation of the effects of MgCl2, 6H20 administration at dose levels of 0, 0.3, 0.6, 1.25, 2.5 and 5% in the diet to male and female mice for up to 13 wk, which showed a significant decrease in body weights in both sexes and an increase in vacuolar changes in the kidneys of males in the 5% groups (unpublished data).

Positive control:

No

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATION: Yes
All animals were observed daily for clinical signs.

BODYWEIGHT: Yes
Mice were weighed weekly for the first 14wk and then every other week

FOOD AND WATER CONSUMPTION: Yes
Food and water consumptions were measured over the 2-day period before each weighting.

HAEMATOLOGICAL: Yes
Blood samples for haematologlcal and clinical chemistry determinations were also obtained from 10 mice/sex/group. Whole blood was analysed for haemoglobin concentration, haematocrit, erythrocyte, leucocyte and platelet counts. The red blood cell indices of mean corpuscular haemoglobin concentration were calculated. Differential leucocyte counts and an estimate of the percentage of nucleated red blood cells, anisocytosls and polychromasia were calculated from blood smears stained.

CLINICAL BIOCHEMISTRY: Yes
The following serum chemical chemistry parameters were determined: glutamic-pyruvic, transaminase, glutamic-oxaloacetic transaminase, alkaline phosphatase, total cholesterol, total protein albumin-globulin ratio and urea nitrogen.

URINE ANALYSES: Yes
Fresh urine samples were obtained from 10 mice/sex/group. Urinalysis included measurements of pH, protein, glucose, ketones, bllirubin, occult blood, urobilinogen and specific gravity.

Sacrifice and pathology:

Any moribund or dead animals received a complete necropsy.
Gross and microscopic examinations were performed on all mice found dead or killed if moribund or at the end of the study;
The following organs were removed from animals necropsied at the end of the study: liver, kidneys, brain, heart and testes or ovaries. The organs were weighted and organ-to-body weight ratios were calculated. The weighted organs and samples of the following tissues were preserved in 10% phosphate-buffered formalin and stained with haematoxylin and eosin for subsequent microscopic pathological evaluation: salivary glands, trachea, lungs, thymus, lymph nodes, stomach, small intestine, large intestine, pancreas, urinary bladder, pituitary, thyroid, adrenals, prostate, seminal vesicles,
eyes, Hardenan glands, spinal cord, siatic nerve and any macroscopic pathological lesions.

Other examinations:

No data

Statistics:

Data were analysed where appropriate using the F- and Student's t-tests.
The significance of differences in the incidences of non-neoplastic or neoplastic lesions between the different groups was evaluated by chi-square or Fisher's exact probabihty tests Differences at P < 0 05 were considered significant.

Clinical signs:

not examined

Mortality:

not examined

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Significant decrease at a dose level of 2% for females

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Greater for female mice at a dose level of 2% than that for male given the same dose.

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

not examined

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

In female of the high-dose group, a significant increase was observed in the level of serum albumin

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

In female of the high-dose group, significant increase was observerd in the absolute and relative weights of the brain and in the relative weights of the heart and kidney and a signicant decrease was noted in the absolute liver weights.

Gross pathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

see details on results

Histopathological findings: neoplastic:

effects observed, treatment-related

Description (incidence and severity):

see details on results

Details on results:

The highest incidence of non-neoplastic lesions was observed for cystic endometrial hyperplasia, which occurred in about 59, 38 and 34% of female in the control and low- and high-dose groups, respectively. Other lesions seen in mice of both sexes occurred in the lymph nodes, spleen, thyroid, lung, forestomach, kidney and ovary. However, the development of biologically significant lesions attributable to the treatment was not observed.

The only tumour that showed an increased incidence, although not strictly in a dose-related manner, was malignant lymphoma/leukaemla in females and to a lesser extent in males. In male mice, a dose-related decrease in the incidence of hepatocellular carcinoma was observed. A decrease an the incidence of hyperplastic (neoplastic) nodules in the liver was also noted in males of both treated groups but the differences from the control value were not significant.

Two cases of bone osteosarcomas were noted in females of the high-dose group, and sarcomas of the uterus were observed in both the control and treated groups These tumours sometimes metastasized to the lung, liver and a number of other organs.

The mean body weights of females, fed diets containing 2% MgCl2 6H20 were lower than those of the control females from wk 8 until the end of the study (wk 104). In the same treatment group, significant decreases and increases in the absolute weights and in the relative weights of some organs were seen. These changes seem to be related to the decrease in body weight. The average food and total test material intake values of females in the high-dose group were higher than those of males given the same dose. The reason for this discrepancy between intake and body weights is unclear. However, no significant treatment related pathological or toxicological changes were observed in any organs in females of the high-dose group. Therefore, this change was considered not to be of biological significance and lay within the range expected for this parameter.

Dose descriptor:

NOAEL

Effect level:

ca. 2 000 mg/kg diet

Based on:

test mat.

Sex:

male/female

Dose descriptor:

NOAEL

Effect level:

ca. 2 810 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Dose descriptor:

NOAEL

Effect level:

ca. 3 930 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Critical effects observed:

not specified

Conclusions:

Under the conditions of this test, for a period of 96 weeks, the NOAELs for female and male mice were, respectively 3,930 mg/kgbw/day (2% in feed) and 2,810 mg/kgbw/day (2% in feed).

Executive summary:

In this study, groups of 50 male and 50 female B6C3F1 mice were given MgCl2, 6H20 at dose levels of 0 (control), 0 5 and 2% in the diet for 96 wk, after which all animals received the control diet for 8 wk and were then necropsied. In females of the high-dose group, a decrease in body weight was observed. However, survival rates did not differ between the treatment and control groups for males or females and clinical signs and urinary, haematological or serum clinical chemistry parameters showed no treatment-related effects. Therefore, this change was considered not to be of biological significance. The NOAEL for female and male mice was, respectively 3,930 mg/kgbw/day (2% in feed) and 2,810 mg/kgbw/day (2% in feed).

Endpoint conclusion

Dose descriptor:

NOAEL

1 309 mg/kg bw/day

Study duration:

chronic

Species:

mouse

Repeated dose toxicity: inhalation - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: inhalation

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Repeated dose toxicity: dermal - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Critical effects observed:

not specified

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The repeated dose toxicity studies were conducted for the oral route.

The inhalation and dermal routes are not appropriate due to, respectively, the nature of the substance (magnesium chloride is deliquescent, it does not stay under a granular form and hydrates quickly) and the low potential of absorption through the skin (the penetration of the dermis by dissolved metal cations was generally low, i.e. in the range of 0.1 -1% [HERAG, Helth Risk Assessment Guidance for metals, 2006]).

Oral route

There are many reliable studies available and all indicated a low toxicological effect or no toxicological effect. The table below summarised these data:

 

Reference	Reliability	Time exposure	Animal/sex	NOAEL (mg/kg bw/day)	LOAEL (mg/kg bw/day)
					Level	Effect
Rudragowda et al., 2010	1	28 days	Wistar rat (male)	1000
		54 days	Wistar rat (female)	1000
Allingham et al., 2009	2	14 days	Wistar rat (male/female)	1500
Tanaka H. et al, 1993	2	13 weeks	B6C3F, mice (male)	5410	12830	Decrease in body weight
			B6C3F, mice (male)	12 830
Takizawa T. et al., 2000	2	13 weeks	Fischer rat (male)	308	1600	slight reduction in body weight and sustained increase in water consumption
			Fischer rat (female)	299	1531
Kurata Y. et al., 1989	2	96 weeks	B6C3F1 mice (male)	3930
			B6C3F1 mice (female)	2810

 

The Rudragowda et al. 2010 is selected as key study and the other studies support this study in the fact that no oral toxicity is observed for repeated exposure, except a decrease in body weight in two studies (Tanaka H. et al, 1993 and Takizawa T. et al., 2000). Although this effect is not regarded as a major toxic effect, the LOAEL are deduced from it.

On the basis of the results, rats being the more sensitive species and the LOAEL and NOAEL were deduced on it (expect for 2 years study, only data available for mice) and presented below:

 

Value	Exposure time	Dose for MgCl2 hexahydrate (mg/kg bw/day)	Dose for MgCl2 anhydrous (mg/kg bw/day)	Basis for effect level
NOAEL	28 days	1000	466
NOAEL	90 days	299	140
LOAEL	90 days	1531	713	slight reduction in body weight
NOAEL	2 years	2810	1309

Justification for classification or non-classification

On the basis of the studies, the only effect observed is a decreased in bodyweight for a dose level of 713 mg/kg bw/day for MgCl2 anhydrous. As indicated in the CLP regulation 1272/2008, this effect is not considered to support classification for specific target organ toxicity, following repeated exposure and the highest guidance values by oral exposure for a classification is 100 mg/kgbw/day for 90 days exposure. In conclusion, the MgCl2 was not classified for repeated dose toxicity according to the CLP regulation 1272/2008.