Tinned foods

Intern. Tin Research and Development Council, Publ. 85 (1939). Historic Tinned Foods. 

The fact that additives are responsible for most of the lead content in the air, in dust and even in most of our food has allowed to estimate, as a result of a study of the intake by the human organism, that at least 60 per cent of the lead in the body comes from lead alkyls. Other food or food related sources (tinned foods, capsules, filters, water pipes) play a much less important role than is generally believed. In areas where the traffic is important the contribution of the motor vehicle can account for... 

Captain Parry took some of Donkin s tinned foods with him on his three Arctic voyages of discovery (1819 to 1825) and found them invaluable. Some tins of meat were landed on the ice when one of his vessels, H.M.S. Fury, in the third expedition met her fate in August 1825 they were found several years later by Captain Ross during his voyages (1829 to 1833) and their contents were in excellent condition. Two tins brought back by Parry himself were opened as late as 1938 and the contents were still perfect — after 114 years. 

Botulinus toxin 0.000 000 03 Meat, sausage, tinned food... 

The small amount of tin found in canned foods is quite harmless. The agreed limit of tin content in U.S. foods is 300 mg/kg. The trialkyl and triaryl tin compounds are used as biocides and must be handled carefully. 

Hot Dip Tin Coating of Steel and Cast Iron. Hot dipping of tin [7440-31 -5] has been largely superseded by electrolytic coating techniques, especially for sheet. However, hot dipping can be the method of choice for complex and shaped parts. Very thin layers of tin are extensively used to passivate steel used for canned goods. Tin is essentially nontoxic, is nearly insoluble in almost all foods, and easily wets and completely covers steel with a pinhole-free coating. 

Some metals used as metallic coatings are considered nontoxic, such as aluminum, magnesium, iron, tin, indium, molybdenum, tungsten, titanium, tantalum, niobium, bismuth, and the precious metals such as gold, platinum, rhodium, and palladium. However, some of the most important poUutants are metallic contaminants of these metals. Metals that can be bioconcentrated to harmful levels, especially in predators at the top of the food chain, such as mercury, cadmium, and lead are especially problematic. Other metals such as silver, copper, nickel, zinc, and chromium in the hexavalent oxidation state are highly toxic to aquatic Hfe (37,57—60). 

Tin. The widespread use of caimed foods results in a daily intake of tin that is ca 1—17 mg for an adult male (154). At this level it has not been shown to be toxic. Some grains also contain tin. Too much tin can adversely affect 2inc balance and iron metaboHsm. EssentiaUty has not been confirmed for humans. It has been shown for the rat. An enhanced growth rate results from tin supplementation of low tin diets (85). Animals on deficient diets exhibit poor growth and decreased feed efficiency (155). 

Tinplate provides an outlet for over one-third of the primary tin used in the United States. In 1980, ca 3.7 x 10 t of tinplate were produced in U.S. steel nulls. Total world production in 1980 was 13.6 x 10 t. In the United States in 1980, ca 56 x 10 base boxes was used to make food containers (one base box comprises an area of 202,000 cm or ca 31 in. ). 

Tests have shown that considerable quantities of tin can be consumed without any effect on the human system. Small amounts of tin are present in most hquid canned products the permitted limit of tin content in foods is 300 mg/kg in the United States and 250 ppm in the UK, which far exceed the amount in canned products of good quaUty (19) (see also Tin compounds). 

The coating thickness may range from 0.0025 to 0.05 mm, depending on the type of protection required. Pure tin coatings are used on food-processing equipment, milk cans, kitchen implements, electronic and electrical components, fasteners, steel and copper wire, pins, automotive bearings, and pistons. 

Toxicology. Inorganic tin and its compounds are generally of a low order of toxicity, largely because of the poor absorption and rapid excretion from the tissues of the metal (42—49). The acidity and alkalinity of their solutions make assessment of their parenteral toxicity difficult. The oral LD q values for selected inorganic tin compounds are Hsted in Table 2. It is estimated that the average U.S. daily intake of tin, which is mostly from processed foods, is 4 mg (see Food processing). 

H. Cheftel, Tin in Food,]o m. EAO/WHO Eood Standards Program, 4th Meeting of the Codex Committee on Pood Additives, PEPT, 1967, oint PAO/WHO Pood Standards Branch (Codex Alimentarius), EAO, Rome. 

Copper and copper alloys resist corrosion by most food products. Traces of copper may be dissolved and affect taste or metals are often tin coated. 

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