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Talc as a pure chemical compound is a hydrous magnesium silicate, [Mg6 (Si8O20) (OH4)], that exists in sheetlike crystalline forms or as fibers. The purity and physical form of any sample depends on the source of the talc and on the minerals found in the ore body from which it is refined. Talc can exist in many forms and depending on the ore source in can be found in a pure form or mixed with asbestos or silica. Talc used in industrial settings can contain mixtures of silica, amphibole asbestos, tremolite, actinolite, and anthophyllite. Exposure to low-grade talc may give rise to talcosilicosis or talcoasbestosis, in which cases the disease will exhibit the features of silicosis or asbestosis, respectively.
Talco-asbestosis closely resembles asbestosis and is produced by crystalline talc, generally inhaled with asbestos fibers. Pathologic and radiographic abnormalities are virtually identical with those of asbestosis, including calcifications and malignant tumor formation.
Talc containing more than 1% asbestos is considered a human carcinogen.
The first form, talco-silicosis, is caused by talc mined with high-silica-content mineral. Findings in this form are identical with those of silicosis.
This type of talc is less fibrogenic than the others.
Pure talcosis results from the inhalation of pure talc without contamination from other mineral sources. It is found in occupational and non-occupational settings associated with cosmetic use of talcum powder.
Excessive use of talcum powder, as well as the accidental aspiration of talc by infants, has been associated with diffuse irregular opacities throughout the upper or lower lung fields, focal fibrosis of the small airways, bronchiolitis, and extensive fibrosis with granuloma formation.
On tissue examination, fibrosis, foreign body granulomas, and multinucleated giant cells are seen.
Radiologic abnormalities include round or irregular opacities.
Physiologic pulmonary testing reveals normal, restrictive, or mixed restrictive and obstructive abnormalities in pulmonary function.
In animals pure talc induces a cytogenic rather than fibrogenic effect on the lungs.
The fourth form, due to intravenous administration of talc, is usually associated with abuse of oral medications and production of vascular granulomas manifested by consolidations, large nodules, and masses. Talcosis may also present as a granulomatous pneumonitis and give rise to a radiological appearance of sarcoidosis or miliary tuberculosis. Such foreign body granulomas are seen especially (but not only) in intravenous drug addicts as result of the injection of crushed talc-containing tablets.
Here are a few toxicologic data sheets made available to us by The Répertoire Toxicologique de la Commission de la Santé et Sécurité du Travail du Québec :
Talc (fibreux)
TALC FIBREUX
Talc, fibrous
FIBROUS TALC
Manufacture of pharmaceutical products, pharmaceutical product.
Solid fibrous, white-gray, odourless
A- Physical State : Solid
B- Solubility in Water : 0.00 g/l at 20 °C
C- Melting Point : 0.00 °C
D- Boiling Point : 0.00 °C
Inflammability
This product is non flammable.
This product is stable.
B-IncompatibilityNo known incompatibility.
C-Products of DecompositionInformation nonavailable
Avoid any contact with the skin. Wear suitable eye protection. In the case of insufficient ventilation, wear a suitable breathing apparatus.
Store in an airtight container.
Collect in a hermetic container duly identified by using a suitable technique in order to prevent the contamination of the environment.
Consult with the regional authority.
This product is absorbed by the respiratory tract.
Cancerogenic to human beings.
In the event of inhalation of vapors or dust, bring the person into a ventilated place.
1 Fiber/cm³ (Respirable)
C1 : Cancerogenic effet demonstrated in human beings.
EM : The exposure to this substance must be reduced to a minimum.
CAS Number : 14807-96-6
Molecular Formula: H2Mg3O12Si4
French names
Talc (non fibreux)
Poudre de talc
Talc
English Names
Talc, not fibrous
Cosmetic talc.
This product can contain quartz (<1%)
Adsorption agent, manufacture of pharmaceutical products.
Powdery, white, odourless.
A- State : Solid
B- Molecular Mass : 379,3
C- Density : 2,7 g/ml at 20 °C
D- Solubility in Water : Insoluble
E- Fusion Point : 950 °C.
Inflammability: This product is non flammable.
A. Stability
This product is stable.
B. Incompatibility
No known incompatibility for this product.
C. Decomposition Products
Information unavailable.
Wear ocular protection, and in the case of insufficient ventilation, a suitable breathing apparatus.
Preserve in an airtight container.
Preserve in a well ventilated place.
Collect wastes and put them in a dustbin.
Put in a dustbin.
1 000 mg/m³
This product is absorbed by the respiratory and digestive tracts.
Several studies in several animal species suggest the absence of effects on antenatal development.
No data concerning the effects on reproduction were found in the consulted documentary sources.
There is no data concerning its excretion or detection in milk.
It cannot be classified as for its cancerogenicity for man (group 3).
II-Evaluation by the A.C.G.I.H.Substance not classifiable as cancerogenic for man (A4 group).
Several studies in animal species suggest the absence of a mutagenic effect.
Rinse eyes with plenty of water and see a doctor. Wash skin with soap and water.
Provoke vomiting if the patient is conscious.
Bring the person into a ventilated place.
Valeur d039;exposition moyenne pondérée (VEMP)
Respirable dust : 3 (mg/m³)
CAS Number : 14378-12-2
Molecular Formula : H2MG3O12SI4
Stéatite
Pierre à savon
Soapstone
Massive talc
Soapstone is a steatite stone and its primary components are magnesite, dolomite, chlorite, and talc.
For thousands of years, soapstone has been used throughout the world for tools, karafes, vases, goblets, sculptures, fireplaces, etc.
In early American history, soapstone was used primarily for building blocks, sculpting and urns.
In early New England, Soapstone uses ranged fom fireplace hearths to countertops, sinks, and oven fireplace stoves.
Currently in the USA and in different parts of the world, soapstone is used for the largest variety of items ever yet - including balusters, stair treads, window sills and island tops.
For over one hundred years, soapstone sinks and tiles have been used in science class rooms and labs along with work tables and counter tops. Its longevity to long term - high traffic use is amazing!
Because of its truly remarkable and natural heat retention characteristics, soapstone is widely used for masonry heater fireplaces, wood stoves, fireplace liners and pizza ovens.
It is also used as a colourant.
A-Physical State : Solid
B-Molecular Mass : 379,2
C-Density : 2,75 g/ml at 20 °C
D-Solubility in Water : Insoluble.
Inflammability : This product is non flammable.
A-Stability
This product is stable.
B-Incompatibility
No known incompatibility for this product
C-Products of Decomposition
Information non available
Ventilate adequately if not wear a suitable breathing apparatus
Collect waste and put in a hermetic container.
Consult with the regional office of the Department of the Environment.
3 000 mg/m³
This product is absorbed by the respiratory tract.
Rinse eyes with plenty of water.
In the event of inhalation of vapors or dust, bring the person into a ventilated place.
If he does not breathe, give the artificial respiration.
Call a doctor.
Respirable dust : 3 (mg/m³)
Total dust : 6 (mg/m³)
Note : The limit applies to dust not containing asbestos and in which the percentage of crystalline silica is lower than 1 %.
By Edouard Bastarache
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Article by Edouard Bastarache
Edouard Bastarache is a well known doctor that has written many articles on the subject of toxicity of ceramic materials and books on technical aspects of ceramics. He writes in both English and French. |
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