ZINC AND TIN IN CANNED VEGETABLES. 1041 



literature of raediciue is full of fatal cases, though it is believed there 

 are none recorded from lead in canned goods. Blythe states that in 

 the five years ending in 1880 there were 324 deaths from lead poisoning 

 registered in England. This is equal to about 20 per cent of the total 

 recorded number of fatal cases from poisons of all kinds. But one 

 was accidental and none were criminal. 



Lead is the most dangerous from a toxicological point of view of the 

 common metals. Its use in any way or place where it is liable to come 

 into contact with food is to be earnestly condemned. Nearly all Euro- 

 pean states render such employment illegal. 



ZINC. 



Zinc is probably not often purposely introduced into canned goods. 

 Zinc salts have been proposed for greening peas, and are said to be in 

 use in France to some extent. The process is said to be a secret. It 

 is not likely, however, that it is often used for this purpose. Around 

 canneries the use of galvanized iron is very common and vegetable 

 juices coming into contact with it could readily dissolve more or less 

 zinc, for that metal is quite soluble in acids, even when weak. Its in- 

 troduction into canned goods might also happen from the use of zinc 

 chlorid as an aid in the soldering operation. 



Toxicologically zinc resembles copper in that, while an emetic in 

 large doses, small quantities are not known to be specially poisonous. 

 The dose of sulphate given as an emetic is about 1.3 grams (equivalent 

 to 294 mg of zinc). For this purpose the salt is regarded as one of 

 the best known. Many cases of fatal poisoning are on record from 

 zinc salts, but these are all from the use of large quantities. Ordi- 

 narily, however, a large dose of a zinc compound is not dangerous, for 

 the reason that the stomach at once rejects it. Little is known rela- 

 tive to the effect of small amounts of zinc, continually administered for 

 long periods of time. 



There is no legitimate reason for this metal being in canned goods 

 and its presence there is usually the result of gross carelessness. It 

 was found in many of the samples of canned vegetables examined and 

 occasionally in relatively large quantity. In the pea sample, No. 10629, 

 packed at Bordeaux by Vve. Garres & Fils, and bought in Florida, it 

 was present to the extent of 85.5 mg per kilo. This may be one of the 

 samples greened by the zinc method just referred to. The peas were 

 bright green. 



TIN. 



Of the possible metallic contaminations, that caused by tin is, next 

 to that of lead, probably the worst. It is assuredly the most common. 

 In every sample of canned goods, which has been put up for any length 

 of time, tin may be found dissolved or rather present in the oxidized 

 orcombined state. Varnishing the inside of the can, whichis sometimes 

 233G8 No. 13 3 



