|Monthly Tech-Tip |
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.
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.
Tin is used in the manufacture of various alloys with zinc, nickel, lead, copper, etc.
Some inorganic compounds are useful as reducing agents, mordants in the textile industry, catalysts in the plastic industry, and the chemistry of ceramic glazes.
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:
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.
Accidental ingestion of inorganic tin compounds can cause a gastrointestinal syndrome characterized by nausea, vomiting and loose stools.
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.
VEMP (Valeur d'Exposition Moyenne Pondérée) = 2mg/m³
By Edouard Bastarache
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.