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diet of animals will produce changes in metabolism which manifest themselves in
various parts of the organism, usually the bones, the pathological condition being
known as " fluorosis." In some recent cases the cause of mottled teeth in children
has been traced to the use of drinking water containing small amounts of fluorine.
Many enamels contain a considerable proportion of fluoride and an acid extract
which was examined showed an appreciable amount of this to have been dissolved.
Since increased amounts of both boron compounds and fluorides weaken the resistance
of enamels to acids there is further justification for the adoption of the acid resistance
test.
(7) Food poisoning.—Five outbreaks of suspected food poisoning were investigated
during the year, and 40 samples were examined in connection with these,
including urine, faeces, vomits, water, tinned tongue, chocolate, fruit jellies, sardines,
butter, margarine and herrings in tomato sauce. In no case was there evidence of
the presence of any poisonous material in significant quantity. Traces of metallic
constituents were found in certain cases, for example lead in the vomits was in one
instance probably derived from a meal of tinned sardines, which commodity sometimes
contains up to 40 parts or more of lead per million. In this particular case
the sardines which were eaten contained only 14 parts per million.
(8) Tinned fish.—Fifteen samples were examined with respect to their lead
content. The question originally arose in connection with tinned sardines, some
recently published research work having shown that the lead content of these varied
greatly, and that some, prepared by a certain process, contained an undesirably
large amount. In the case of sardines the quantity of lead varied in the 9 samples
examined from 9 to 40 parts per million, and in the 6 samples of other tinned fish
from 0 to 3 parts per million.
(9) Bread—Sale of Food (Weights and Measures) Act, 1926.—At the request of
the chief oflicer, public control department, 5 samples were examined in connection
with contemplated legal proceedings under the provisions of this Act. The vendors
had sold the bread in question under the description of " fancy bread," but in each
case analysis revealed no evidence that the sample was other than good quality
ordinary bread.
(10) Calculi.—During the year 22 specimens of renal, vesical and ureteric calculi
from patients in one of the Council's hospitals were examined. The composition
varied greatly in different cases and there appeared to be no definite classification.
The main constituents were calcium oxalate and calcium phosphate though in certain
instances magnesium ammonium phosphate predominated. Smaller quantities of
uric acid, calcium carbonate and organic matter were also found in some cases.
Milk samples.
The total number of milk samples examined during the year in the laboratory
at County Hall was 249. Of this number 136 were of milk supplied to children in the
elementary and residential schools, whilst 105 were from supplies to general, special
and mental hospitals and public assistance institutions, under contracts which require
a minimum of 3.25 per cent, of fat and 8.5 per cent, of other solids, except during
the months of March and April, when the fat must not be less than 3 percent, and
8 were from farms attached to institutions, etc. The quality of the supplies generally,
has been less satisfactory than in recent years, 7 samples (2.9 per cent.) being
deficient in fat.
The condition of the supplies in respect of extraneous matter was again less
satisfactory, for of the 241 contract samples examined 35 (over 14 per cent.) were
found to contain an excessive amount.
In addition to the above, 36 samples of milk supplied to schools and mental
hospitals were examined bacteriologically at the bacteriological laboratory at the
County Hall. The results obtained are shown in the tables set out below.
The milk supplied to schools (other than open-air schools) and mental hospitals
is not purchased under any of the standards specified in the Milk (Special Designations)
Order, 1923, and a standard was adopted for what would be regarded as
ordinary clean milk. The standard was : bacterial content, not more than 300,000
per c.c., and B. coli not to be present in 1 /1,000 c.c. If below this standard, the chief
officer of supplies was informed that the milk could not be regarded as satisfactory.