Chapter XXXVI: Flour Mills

Flour-milling as conducted in this country a few decades ago was, despite the fact that most of the mills were situated in the country, an unhealthy industry. Flour millers died from pulmonary consumption and chest diseases in a larger proportion than men engaged in other trades in the same district. The average life of a miller was said to be forty-three years. Hirt compiled tables of the comparative sickness of millers and bakers, and he showed that while of one hundred bakers seven died from pulmonary phthisis, out of the same number of millers the deaths were ten. Bakers and millers seemed to him to be about equally predisposed to emphysema of the lungs, but as regards pneumonia the mortality figure for bakers was 8.4 per cent. as against 42 per cent. for millers. These statistics are taken from a German source, and it is difficult to explain the very heavy mortality rate from pneumonia in millers compared with that of bakers.

Until within thirty years ago all the wheat and oats in this country were ground between revolving stones. During the grinding a considerable amount of fine dust was given off, the continual inhalation of which was held responsible for much of the ill-health of the operatives. So unhealthy was the occupation of milling believed to be twenty years ago, that Friendly Societies would not accept operative millers as members. To-day no objection is raised. In addition to injury to health from breathing the dust-laden atmosphere, there was a risk from fire owing to the highly explosive character of the dust. While danger to life from explosions in flour mills still to some extent prevails, both it and the risk to health from inhalation of the dust have materially diminished. There is the widest divergence possible between the old and the new methods of milling. The introduction of the steam roller system of milling from Buda-Pesth, and the fact that nearly all the various processes are carried on inside closed machinery, have cleared the atmosphere of modern flour mills and converted what was admittedly a dangerous trade into one that compares very favourably with most occupations. Wherever the old method of milling is still carried on the atmosphere is found laden with a very fine dust, mostly flour. This with each inspiration is drawn into the bronchial tubes of the miller, and forms plugs with the mucus secreted by these passages. The plugs, owing to their tenacity, are dislodged with difficulty. It is not contended that the flour itself reaches the lungs; probably the whole, or at any rate the most of it, becomes entangled in the mucus of the smallest bronchial tubes, but in the dust there are other things than flour present, _e.g._, portions of the husks of harder grain than wheat, portions of hairs of oats, bristles of rye, and particles of mineral from the grinding stones (see Microphotographs, page 276), so that through one thing and another, and in consequence of the repeated bronchial irritation and the cough caused by respiring the dust-laden air, a strain is imposed upon the lungs that leads to over-distension of the air cells, or what is known as pulmonary emphysema. That portions of bristle, etc., are capable of being inhaled into the deeper recesses of the respiratory passages is shown by the presence of these bristles on microscopical examination of the expectoration that has been discharged after hard coughing.

As a nation we are dependent upon foreign countries for our food supplies, especially wheat. Some of the wheat that is imported is extremely dirty, particularly that from the River Plate, India, and Persia. It not only contains small stones and sand, and the husks of other seeds, but often particles of soil that have been contaminated by manure. In going over a large modern flour mill one is struck by the amount of dirt that is taken out of wheat. It is therefore necessary to clean the grain, which is done by first removing all solid impurities and then washing it. To clean it, the wheat is passed through a separator composed of sieves that are kept vibrating. By this means the larger impure particles are removed, while by the operation of a strong current of air the lighter dust is sucked away. After this preliminary cleaning the wheat is taken to rotatory sieves, which size the grain and thereby separate the larger from the smaller seeds. It is now ready to be washed. This is done by allowing the wheat to fall into a tank of warm water, through which a stream is constantly running. From this it is removed to dryers and coolers. It is only the very dirty wheat that is washed. Some of it is simply scoured and brushed inside a conical iron cylinder by means of beaters or brushes that are revolving rapidly. The dust given off escapes through fine slot holes.

In modern flour mills the dangers that operatives are exposed to are: (1) those incidental to the machinery; (2) fire and explosions; and (3) inhalation of dust. It is with the latter that we are here most concerned. The cleaning of wheat is a dusty process, but it is usually carried on within enclosed machinery, and so long as this and all the covered-in spaces are provided with fans that are kept in good order, and the pipes leading away from these to the dust chambers are kept patent, the workmen do not seem to incur any great risk to health. Attention, however, must be given to keeping the suction-pipes clean and the fans in good order, otherwise, as cleaning is a very dirty process, the men would assuredly suffer in their chest. At several of the large flour mills where Oriental wheat is ground, and to the grains of which particles of manure are often adherent, I have on several occasions interrogated the men as to whether any illness had ever followed the washing of the foreign wheat, but in no instance could I learn of any illness being traceable to such a source. Once the wheat has been cleaned and brushed or washed, it is put through the rollers and is milled into flour. This consists of not one but many processes, all of which are conducted in enclosed chambers, the product at each particular stage being lifted and carried onwards by self-regulating machinery and elevators from one part of the mill to another. Where the fittings of the machinery are good, no dust practically escapes. Hence it is that flour-milling has ceased to be the harmful industry it formerly was. In filling the sacks with flour, and in cleaning returned sacks, there is often a considerable amount of dust given off, but mechanical contrivances are now in operation that greatly minimise the amount of dust, so that this particular operation too has become less dangerous than it once was.

THOMAS OLIVER.