London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Carshalton 1956
[Report of the Medical Officer of Health for Carshalton]
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Classification of the milk samples and the results of the tests are as follows:
| Designation under which sold | No. of samples | Methylene Blue Test | Phosphatase Test | Turbidity Test | |||
|---|---|---|---|---|---|---|---|
| Satisfactory | Unsatisfactory | Satisfactory | Unsatisfactory | Satisfactory | Unsatisfactory | ||
| Pasteurised | 161 | 160 | 1 | 160 | 1 | — | — |
| T.T. Pasteurised | 45 | 44 | 1 | 45 | — | — | — |
| Sterilised | 8 | — | — | — | — | 8 | — |
| 214 | 204 | 2 | 205 | 1 | 8 | — | |
Biological Samples.
Raw milk produced on the 3 farms in the district is submitted to
animal inoculation test before being treated in any way. Twelve such
examinations were made in the year and all were reported to be free from
tuberculosis infection.
Milk and Dairies Regulations, 1949—Regulation 20.
No action was called for under this section which empowers the
Medical Officer of Health to deal with milk which he has reason to believe
might be a source of infection to man.
Qualitative Analysis.
The number of milk samples submitted to the Public Analyst was 211.
One, a sample of "Channel Islands" milk, was found to be adulterated or
otherwise irregular. Of the total samples, 28 were Channel Islands or South
Devon milks which when sold under these designations must contain 4%
fat as against the legal limit of 3% for milk not so designated.
The average fat and non fatty solids content of the 28 samples of
Channel Islands milk was 4.32% and 9.00% respectively. That for the
other 183 samples of milk 3.61% and 8.72%.
Ice Cream
Since 1947 ice cream samples submitted for bacteriological examination
have been classified into four grades. These are based on the length of time
the samples take to reduce methylene blue. The grades in the order of
descending hygienic standard are Grade I taking 4½ hours or more, Grade II
taking 2½ to 4 hours, Grade III taking ½ to 2 hours and Grade IV, the
poorest standard, reducing methylene blue immediately. The view is held
that over at least a six monthly period, 50% of a vendor's samples should
fall into Grade I, 80% in Grades I & II, not more than 20% in Grade III
and none in Grade IV. The reason for this is that owing to the numerous
factors governing the hygienic quality of ice cream, it is unwise to pay too
much attention to the results of any single sample.
From the table which
follows it will be seen that judged by this standard there has been a progressive
improvement in the purity of ice cream sold in the district to the
point last year where only 1 out of 96 samples failed to reach the highest
grade and that one was in Grade II.
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