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be unnecessary; and in view of the fact that unsound cans may be vented,
resealed and reprocessed, there is justification for regarding resoldered cans
with suspicion. Port Medical Officers have inquired what procedure they should
adopt in regard to cans which show evidence of having been resoldered, and
have been advised that such cans should be condemned."
If a can is blown, the contents should not be allowed to go for human consumption
in any form: There is, I believe, some lack of uniformity in dealing with blown tins
of fruit pulp, which, I understand, are allowed to go for jam making on the grounds
that the pulp will be boiled, killing any bacteria or yeasts and stopping fermentation.
This seems to me quite wrong practice. In the first place there may be extensive
detinning of the can and the dissolved tin will go into the jam; in the second place
the contents are unsound and should therefore be condemned, and in the third place
if the canner and the merchant can have blown cans for jam-making why should they
go to the trouble and expense of preparing and packing their product in such a way
that it will not blow before it is used ? Surely the good canner, as well as the general
public, might reasonably complain if we permit blown cans of fruit or pulp to be used
in the manufacture of jam. We may be accused of wasting useable food, but it is
the canner not us, who is responsible for the waste just as it would be the jam
manufacturer and not the consumer who would benefit if we allowed him to have
the blown cans.
I would take a similar view with regard to allowing blown tins of condensed milk
to be used in the manufacture of toffee.
I understand that it is the practice of some food inspectors to return blown cans
to the cases when the proportion of unsound cans is not sufficient to warrant a complete
examination of the consignment, the argument being that, since the decision on the
sample examination is that the whole of the consignment is to be passed, none of the
cans should be removed. While I admit that there would be, in the unexamined
portion of the consignment, a proportion of unsound cans approximately equal to
that in the sample examined and, therefore, a few unsound cans are being allowed to
go forward, I hold very strongly that such unsound cans as actually come under the
notice of the food inspector should be removed and condemned.
So far I have only dealt with one or two special points in regard to the external
inspection of canned foods, but even when cans appear to be quite sound we ought
to have the contents examined from time to time for metallic contamination and the
presence of prohibited colouring matters and preservatives.
You all know the trouble there has been with lead in Portuguese sardines. The
highest figure we have had in the Port of London is 78 parts of lead per million, and
amounts over 20 parts per million were not infrequent. It is noteworthy that
considerable variation has been found in the degree of contamination of the contents
of different tins from the same consignment, and, therefore, we always take at least
six tins from different cases. I believe that the contamination is mainly derived,
not from the tin-plate containers or the solder with which they are sealed, but from
the grills in which the Portuguese steam the fish. These grills are made of iron wire
and were coated with solder containing a very high proportion of lead. Twenty-five
consignments representing nearly 250,000 tins of sardines have been rejected in the
Port of London and returned to the packers under guarantee that they would not be
reshipped to this country, and the packers have been recommended to coat the grills
with pure tin. Recent consignments have been very much more satisfactory, though
the degree of lead contamination has not yet been reduced to the minimum. French
sardines are not cooked in the same way, and a solder containing very little lead is
used for sealing the cans, consequently they have given us no trouble.
We have found lead in smaller quantities in a number of other canned products,
for example, tunny fish 13 parts per million, paté-de-foie gras 10 parts per million,
anchovies 8 parts per million, peeled shrimps 7 parts per million, crab paste 6 parts
per million.
Merchants have argued that the amount of lead in sardines is not dangerous to
health, and have told me how many tins of sardines they themselves have eaten,