Talc (Mg3H2(SiO3)4)

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

other: Published data

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Reliability score 2 on the basis of the weight of evidence found during review of public documents existing relating to toxicological data

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 of Magnesium hydroxide also should be taken into account

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

2010

Reference 2

Reference Type:

review article or handbook

Title:

MSDS for Magnesium hydroxide

Author:

Albemarle Corporation Ltd

Year:

2010

Bibliographic source:

Albemarle Corporation Health & Environment Department

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Magnesium hydroxide

EC Number:

215-170-3

EC Name:

Magnesium hydroxide

Cas Number:

1309-42-8

IUPAC Name:

magnesium dihydroxide

Test material form:

aerosol dispenser: not specified

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Species
Rat: Crl:WI(Han) (outbred, SPF-Quality)
Recognised by international guidelines as the recommended test system (e.g. OECD, EC).
Source: Charles River Deutschland, Sulzfeld, Germany.
Number of animals
5 males and 5 females (females were nulliparous and non-pregnant) per exposure level.
Age and body weight
Young adult animals were selected (approximately \ weeks old).
Animals used within the study were of approximately the same age and body weight variation did not exceed +/- 20% of the sex mean.
Identification
Earmark
Health inspection
A health inspection was performed prior to commencement of treatment, to ensure that the animals were in a good state of health.

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

air

Details on inhalation exposure:

Test atmosphere generation
Administering the test substance to a stream of dry pressurized air using a combination of a spiral feeder and air mover generated an aerosol. The aerosol was passed through a cyclone, allowing larger particles to settle, before it entered the exposure chamber (Appendix 1, Figure 1). The mean total airflow was 47 L/min. From the exposure chamber the test atmosphere was passed through a filter before it was released to the exhaust of the fume hood.

Nominal concentration
The nominal concentration was calculated by dividing the amount of test substance used by the volume of pressurized air (average air flow times exposure time) entering the exposure chamber used for exposure of the animals.

Actual concentration
The actual concentration was determined twelve times during the exposure period. Samples were drawn from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber. Samples were drawn through a glass fiber filter (type APFC04700, Millipore, Billerica, MA, USA). The collected amount of the test substance in the air sample was measured gravimetrically. Sample volumes were measured by means of a dry gas meter (type G 1.6, Actaris Meterfabriek B.V., Dordrecht, The Netherlands).

Subsequently the mean concentration with the standard deviation was calculated.

The particle size distribution was characterized twice during the exposure period. The samples were drawn (2 L/min) from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber (Appendix 1, Figures 1 and 2). The samples were collected with an 8 stage Marple personal cascade impactor containing fiber glass filters (SKC 225-713, fiber glass, SKC Omega Specialty Division, Chelmsford, MA, USA) and a fiber glass back-up filter (SEC-290-GFS, Westech, Upper Stondon, Bedfordshire, England). Amounts of test substance collected were measured gravimetrically. Subsequently the Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (GSD) were determined.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

The collected amount of the test substance in the air sample was measured gravimetrically. Sample volumes were measured by means of a dry gas meter (type G 1.6, Actaris Meterfabriek B.V., Dordrecht, The Netherlands).

Duration of exposure:

4 h

Concentrations:

The mean actual concentration was 2.1 ± 0.47 mg/L. The nominal concentration was 21.7 mg/L resulting in a generation efficiency (ratio of actual and nominal concentration) of 10%. The concentration measurements distributed over time showed that the substance was sufficiently stable

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 15 days
- Frequency of observations and weighing: Days 1 (pre-administration), 2, 4, 8 and 15.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,organ weights, histopathology, other: On Day 1, one and three hours after exposure and once daily thereafter until Day 15.

Statistics:

No statistical analysis was performed.

Results and discussion

Effect levels

Effect levels 1

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.1 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Effect levels 2

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2 100 mg/m³ air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: To convert mg/l into mg/m³ 1 mg/m³ = mg/l x 1000 (2.1 x 1000=2100 mg/m³)

Mortality:

No mortality occurred.

Clinical signs:

other: No clinical signs were noted during exposure. After exposure, ptosis and/or piloerection were noted in two males and one female on Day 1 only.

Body weight:

Overall body weight gain in males and females was within the range expected for rats of this strain and age used in this type of study.

Any other information on results incl. tables

To convert mg/l into mg/m³     

1m³=1000L

        

1 mg/m³=mg/l x 1000, 2.1mg/l x1000=2100 mg/m³

 

Applicant's summary and conclusion

Interpretation of results:

other: practically nontoxic

Conclusions:

The inhalatory LC50, 4h value of Magnesium hydroxide in Wistar rats was established to exceed 2.1 mg/L.

Executive summary:

Groups of 5 male and female Wistar rats were treated with Magnesium hydroxide as aerosol during 4 hours. No mortality or other relevant adverse effects were observed. An inhalatory LC50 (4h)value for magnesium hydroxide exceeding 2.1 mg/L was determined, being this value the maximum feasible concentration that could be tested.