Talc (Mg3H2(SiO3)4)

Respiratory sensitisation

Administrative data

Endpoint:

respiratory sensitisation: in vivo

Type of information:

other: Published data

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Justification for type of information:

Pure talc has the formula Mg3Si4O10(OH)2 and a chemical composition of 31.88% by weight (wt) magnesium oxide (MgO), therefore the health effects should be taken into account

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1992

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

1986

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

In experimental exposure chambers, aerosols were prepared using particulates that were collected from electrostatic filters in a Slovak magnesite
work, consisting of 88.5% MgO, 7.6% Fe2O3, 2.7% CaO, 0.5% Al2O3, SiO2, and traces of other elements and having a mean dust particle diameter of 1.8 μm. Wistar rats and C57 BL mice were exposed to concentrations ranging from 10- 1000 mg/m3, 3-5 hours/day, 5 days/week, for 3-9 months

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Magnesium oxide

EC Number:

215-171-9

EC Name:

Magnesium oxide

Cas Number:

1309-48-4

Molecular formula:

MgO

IUPAC Name:

Magnesium oxide

Test material form:

solid

Test animals

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

A total of 15 male Wistar rats, housed at a biomonitoring station, were exposed to the emissions from a magnesite facility

Test system

Route of induction exposure:

inhalation

Route of challenge exposure:

inhalation

Vehicle:

unchanged (no vehicle)

Concentration:

concentrations ranging from 10- 1000 mg/m3, 3-5 hours/day, 5 days/week, for 3-9 months

Results and discussion

Results:

The findings showed that magnesite dust was eliminated by both blood and lymph.
After a single exposure, 41% of magnesite dust was eliminated with an intermediate fibrogenic effect.
Following long-term exposure, the ability to eliminate dust diminished. Serum magnesium increased moderately during exposure and returned to the initial level 25 days after the end of the exposure. There was a significant increase in magnesium excretion with urine. The findings showed that inhaled dust was gradually dissolved in the body. The magnesium content was evaluated in the reticuloendothelial organs (liver and spleen) 25 days after the last exposure and was found to increase by 20.1% in the spleen and by 15.6% in the liver.
A concomitant histological exam of internal organs confirmed that the dust was retained in the lungs (without fibrotic changes), that particles were present in the spleen (sinusoid macrophages) and that the red pulp was hemorrhagic.
No signs of pulmonary fibrosis were found even after 6 months after the last exposure. Dust particles were found in thickened interalveolar septa and macrophages.
Proliferative histiocytic elements with particles present were found in the subcapsular sinuses and medulla of hilus lymphatic nodes.

Applicant's summary and conclusion

Interpretation of results:

other: not sensitising

Conclusions:

No signs of pulmonary fibrosis were found even after 6 months after the last exposure..The findings showed that magnesite dust was eliminated by both blood and lymph.

Executive summary:

After a single exposure, 41% of magnesite dust was eliminated with an intermediate fibrogenic effect.

Following long-term exposure, the ability to eliminate dust diminished. Serum magnesium increased moderately during exposure and returned to the initial level 25 days after the end of the exposure. There was a significant increase in magnesium excretion with urine. The findings showed that inhaled dust was gradually dissolved in the body. The magnesium content was evaluated in the reticuloendothelial organs (liver and spleen) 25 days after the last exposure and was found to increase by 20.1% in the spleen and by 15.6% in the liver.

A concomitant histological exam of internal organs confirmed that the dust was retained in the lungs (without fibrotic changes), that particles were present in the spleen (sinusoid macrophages) and that the red pulp was hemorrhagic.

No signs of pulmonary fibrosis were found even after 6 months after the last exposure. Dust particles were found in thickened interalveolar septa and macrophages.

Proliferative histiocytic elements with particles present were found in the subcapsular sinuses and medulla of hilus lymphatic nodes.