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Public Analyst's Comments, 1963
The year 1963 has been one of considerable activity amongst public
analysts and although these new activities may not have applied
specifically to many of the samples examined for Sutton and Cheam it is
rewarding to know that efforts to protect the consumer in one part of Surrey
or, in fact in one part of England, automatically protects the consumer in
general. For this reason, in these notes, I have no hesitation in writing
about what we have been doing in general terms in the knowledge that in
the long run everyone benefits.
First, there is the work which we started in 1962 and which has been
continued and extended in 1963 to develop and maintain a colony of a
particular species of fly to act as a biological test for the possible
presence of certain pesticide residues in food arising from the widespread
use of sprays and dusts in agriculture. The various chemicals so used are
not liable to leave any significant residue if the instructions for use issued
by the Ministry of Agriculture, Fisheries and Food are obeyed, but the
toxicity of some of these chemicals is so great that the added confidence
provided by the use of the 'fly' test, amongst others, is one which the
public analyst can help to provide. Probably the greatest risk is with raw
foods such as fruit and vegetables and all such samples are tested where
appropriate by this test and others to establish that the residue is either
absent or well below a safe limit. Briefly, an extract of the food is made
with a suitable organic solvent, the solvent is removed and a number of
flies are 'exposed' to this extract and a count is made of the living flies
after a time of anything up to 2 days. The most potent'insecticides act on
contact and the flies do not necessarily 'feed' on the extract. An abnormally
high death rate of flies calls for further investigation. No positive test was
recorded on numerous samples of human food tested during the year.
A second danger which has been receiving our attention is that of the
presence of penicillin or other antibiotics in milk. This arises from the use
of penicillin to 'cure' mastitis in cows, high concentrations being injected
into the udder. The milk from such cows is not supposed to be used for
human consumption until at least 48 hours after, but there is a risk of it
being sold before this time has elapsed. In my laboratory all samples of
milks direct from the farm are subjected to a test designed to detect very
small amounts of penicillin. Here again, in that part of the year since the
test was applied no very significant quantity of penicillin has been detected
in any one sample, but the time will probably come when it will be
considered an offence to have even a trace of penicillin in milk.
Thirdly, much more attention has been paid to samples of modern drugs
in recent months, not because we have any reason to doubt their quality or
purity, their manufacture normally being in the hands of people of high
integrity and repute, but because it is considered to be the duty of the
public analyst under the Food and Drugs Act to keep a watch on these
matters. Considerable confusion has arisen, particularly as a result of the
thalidomide affair, and it has been implied that Food and Drugs Authorities
and their public analysts have not been doing the work of enforcement
with which they have been entrusted. It cannot be too strongly emphasized
that the safety of drugs as such when used for a medical purpose is one
which must be decided by medical authority as a result of extensive clinical
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