Tin and Inorganic Compounds
By Edouard Bastarache
Introduction
:
Tin is a malleable white metal which can
easily be rolled in thin sheets. In the soil, tin concentration
varies from 2 to 200 mg/kg, and the air of the rural environment
contains less than 10ng/m³. In food, the amount is probably
lower than 1 mg, but this amount can increase much if ingested
foodstuffs are stored in tin containers. In the absence of an
inner lining (resin or lacquer), the foodstuffs stored in tin cans
can contain up to 100 mg/kg.
Main compounds
:
- stannic oxide,
- tin tetrachloride,
- stannic chloride,
- stannous chloride,
- stannous sulphate,
- sodium stannate,
- potassium stannate
Uses and exposure
sources :
1 - Containers :
Tin covered metal sheets are used in the
manufacture of cans, containers for aerosols and equipment for
dairies.
Tin sheets resist corrosion and are
easily welded.
2 - Alloys :
Tin is used in the manufacture of
various alloys with zinc, nickel, lead, copper, etc.
3 - Other uses :
Some inorganic compounds are useful as
reducing agents, mordants in the textile industry, catalysts in
the plastic industry, and the chemistry of ceramic glazes.
Intoxication by
inorganic tin :
A - Inhalation :
1 - Metal fume fever :
The inhalation of tin oxide fumes can
cause a syndrome similar to brass fume fever.
2 - Stannosis :
Exposure to tin oxide fumes and dusts
can cause a benign pneumoconiosis: stannosis.
It is a radiological finding : very
small dense opacities resembling those of barytosis (barium
sulphate). Generally, there are no subjective symptoms and
pulmonary function tests may remain completely normal.
3 - Bronchial syndrome :
Exposure of workers in a bottle-factory
to a stannous chloride solution has already caused :
- wheezing,
- exertional shortness of breath,
- cough,
- thoracic pain.
It seems that the causal agent was the
hydrochloric acid released by the action of heat on the aqueous
stannous chloride solution
4 - Hemolysis :
Tétrahydrogenated tin (SnH4) is a
hemolytic poison.
B - Ingestion :
Accidental ingestion of inorganic tin
compounds can cause a gastrointestinal syndrome characterized by
nausea, vomiting and loose stools.
C-Skin :
Some inorganic tin compounds can cause
irritation of the skin or the eyes because of acid or alkaline
reactions produced with water.
Tin tetrachloride, stannous chloride and
stannous sulphate are strong acids; sodium stannate and potassium
stannate are strong alkalies.
Tin is also a contact skin sensitizer,
this was confirmed by skin tests.
Quebec's exposure limit
:
VEMP (Valeur d'Exposition Moyenne
Pondérée) = 2mg/m³
References :
1 - Occupational Medicine,Carl Zenz,
last edition.
2 - Clinical Environmental Health and
Toxic Exposures, Sullivan & Krieger; last edition.
3 - Sax's Dangerous Properties of
Industrial Materials, Lewis C., last edition.
4 - Toxicologie Industrielle et
Intoxications Professionnelles, Lauwerys R.R. last
edition.
5 - Chemical Hazards of the
Workplace, Proctor & Hughes, 4th edition
Edouard Bastarache M.D.
Occupational & Environmental Medicine
Author of "Substitutions for Raw Ceramic Materials"
Tracy, Québec, CANADA
edouardb@sorel-tracy.qc.ca
http://www.sorel-tracy.qc.ca/~edouardb/
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