Magnesium

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

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

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Materials and methods well described; results presented adequately in text, tables and figures.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Biological effects of inhaled magnesium sulphate whiskers in rats

Author:

Hori, H.; et al.

Year:

1994

Bibliographic source:

Occup. Environ. Med. 51: 492-499.

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Subchronic effects of inhaled whiskers in rats.

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Magnesium sulphate

EC Number:

231-298-2

EC Name:

Magnesium sulphate

IUPAC Name:

231-298-2

Constituent 2

Reference substance name:

7487-88-9

Cas Number:

7487-88-9

IUPAC Name:

7487-88-9

Constituent 3

Reference substance name:

magnesium sulfate

IUPAC Name:

magnesium sulfate

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report): magnesium sulfate whiskers consisting of magnesium sulfate and magnesium hydoxide.
No further details are given.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 4 weeks
No further details are given.

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: air

Remarks on MMAD:

MMAD / GSD: Count median length (µm): long whiskers = 12.0 +/- 2.3 and short whiskers = 4.9 +/- 2.1
Count median diameter (µm): long whiskers = 0.44 +/- 1.6 and short whiskers = 0.31 +/- 1.5

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: consisted of a whisker generator and an exposure chamber (volume 0.43m^3) and was made from stainless steel.
- System of generating particulates/aerosols: whiskers were premixed with glass beads (250µm) and put into a hopper. The whiskers mixed with glass beads were supplied from the hopper to a fluidised bed generator. Air from a compressor was passed through a silica gel fixed bed and introduced into the bottom of the fluidised bed. Glass beads with whiskers were moved in the fluidised bed due to airflow and the whiskers were detached from the glass beads.
- Temperature, humidity in air chamber: 25°C, 50%
- Air flow rate: air with whiskers was introduced from the top of the chamber with a flow rate of 150 L/minute.
No further details are given.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The whisker concentration in the chamber was monitored continuously with a digital dust indicator.

Duration of treatment / exposure:

4 weeks

Frequency of treatment:

6 hours per day, 5 days per week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
2.3 mg/m3 (short whiskers)
Basis:
nominal conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
4.0 mg/m3 (long whiskers)
Basis:
nominal conc.

No. of animals per sex per dose:

124 rats were divided into 3 groups: 42, 42 and 40 rats per group for short whiskers, long whiskers and controls, respectively

Control animals:

yes

Details on study design:

no data

Positive control:

no data

Examinations

Observations and examinations performed and frequency:

Body weights of the rats were measured every week to obtain the growth curves.

Sacrifice and pathology:

- 5 or 6 rats in each group were killed and dissected at 1, 2, 3 and 4 weeks after the beginning of the exposure, and 2 and 4 weeks, 6 months and 1 year after the end of the exposure.
- In all dissections, the weights of body and organs (lung, liver, kidney and spleen) were measured.
- Lungs were divided and a part was used for the determination of the whiskers; remaining portions were used for histopathological examination.

Statistics:

no data

Results and discussion

Results of examinations

Clinical signs:

not specified

Mortality:

not specified

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not specified

Food efficiency:

not specified

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

not specified

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

not specified

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Details on results:

BODY WEIGHT AND WEIGHT GAIN:
Growth curves and survival rates were similar in all groups.

ORGAN WEIGHTS:
Organ weights did not show significant differences.

HISTOPATHOLOGY: NON-NEOPLASTIC.
There was no effect on the Mg contents in the lungs of different groups. Histopathology did not indicate significant differences between control and exposure groups.

No further details are given.

Effect levels

Dose descriptor:

NOAEC

Remarks on result:

not determinable

Remarks:

no NOAEC identified

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Subchronic inhaltion exposure of rats with the test material (short and long magnesium sulphate whiskers) did not affect growth curves, survival rates and organ weights in treated rats compared to control animals. There was no effect on the Mg contents in the lungs of different groups. Histopathology did not indicate significant differences between control and exposure groups.