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Don't store food in an opened tin can, or re-use empty cans to cook or store food. This is because when a can has been opened and the food is open to the air, the tin from the can might transfer more quickly to the can's contents.
This advice doesn't apply to foods sold in cans that have resealable lids, such as golden syrup and cocoa, because these types of food donít react with the can.
Rat studies have shown that tin-deficient diets resulted in poor growth, reduced feeding efficiency, hearing loss, and bilateral (male pattern) hair loss. Tipton and Shafer examined tin in human tissue after accidental deaths. They noted that tin was found in the aorta, brain, heart, kidney, liver, muscle, ovary, spleen, pancreas, testes, stomach, and uterus, but none was found in the thyroid of any victim, while the prostate, which usually shows no other trace element, had tin.
Daily dietary intakeof tin from various food sources is in the 1 - 3 mg range, which is less than 1/10th of the daily intake obtainedyears ago before lacquering tin cans, switching to aluminum cans, or, in the more distant past, when tin cupsor tin pans were still in use. Since bronze contains copper and tin, the use of tin has been established wellpast the Bronze Age, several thousand years ago.
Mutagenic studies on metallic tin and its compounds have been negative. Long-term animal carcinogenic studies have shown fewer malignant tumours in animals exposed to tin than in controls. Human volunteers developed mild signs of toxicity with tin, given in fruit juices, at a concentration of 1400 mg per litre. The WHO 1973 permissible limit for tin in tinned food is 250 micrograms per kg. The adult daily intake of tin was about 17 mg per day in 1940, but it has now decreased to about 3.5 mg, due to improvements in technique of tinning with enamel overcoat and crimped lids to minimize exposure to tin and lead solder. This level is well below the level of 5-7 mg per kg body weight shown to give rise to toxic symptoms. Tin deficiency has not been described in man. Amounts in excess of 130 mg per day have been shown to accumulate in liver and kidneys. Many of the organotin compounds are toxic; the most toxic being trimethyltin and triethyltin, which are well absorbed from the gastrointestinal tract. Most of the other alkyl and aryltin compounds are poorly absorbed from the gastrointestinal tract, and are therefore less toxic when given orally than when given parenterally. The main results of toxicity are skin and eye irritation;