The late Dr Parkes has given a summary of various reports that have from time to time been issued as to the effects of sewage farms upon the public health and comfort. He says:—“That sewage farms, if too near to houses, and if not carefully conducted, may give off disagreeable effluvia is certain; but it is also clear that in some farms this is very trifling, and that when the sewer water gets on the land it soon ceases. It is denied by some persons that more nuisance is excited than by any other mode of using manure. As regards health, it has been alleged that these farms may—1st, give off effluvia which may produce enteric fever or dysentery, or some allied affection; or, 2nd, and in the spread of
entozoic diseases; or, 3rd, make ground swampy and marshy, and may also poison wells, and thus affect health.”
The evidence of Edinburgh, Croydon, Aldershot, Rugby, Worthing, Romford, the Sussex Lunatic Asylum, is very strong against any influence in the production of typhoid by sewage farms effluvia. On the other hand, Dr Clouston’s record of the outbreak of dysentery in the Cumberland Asylum is counter evidence of weight, and so is one of the cases noted by Letheby of typhoid fever outbreak in Copley, when a meadow was irrigated with the brook water containing the sewage of Halifax.
The negative evidence is, however, so strong as to justify the view that the effluvia from a well-managed sewage farm do not produce typhoid fever, or dysentery, or any affection of the kind. In a case at Eton in which some cases of enteric fever were attributed to the effluvia, Dr Buchanan discovered that the sewer water had been drunk; this was more likely to have been the cause.
With regard to the second point, the spread of entozoic diseases by the carriage of the sewer water to the land, has been thought probable by Cobbold, though as solid excreta from towns have been for some years largely employed as manure, it is doubtful whether the liquid plans would be more dangerous. The special entozoic diseases which, it is feared, might thus arise, are tapeworms, round worms, trichina, Bilharzia, and distoma hepaticum in sheep. Cobbold’s latest observations show
that the embryos of Bilharzia die so rapidly, that even were it introduced into England there would be little danger.
The trichina disease is only known at present to be produced in men by the worms in the flesh of pigs which is eaten, and it seems doubtful whether pigs receive them from the land. There remain, then, only tapeworms and round worms for men and distoma hepaticum for sheep to be dreaded. With regard to these, the evidence at present is negative; and though much weight must be attached to any opinion of Cobbold’s, this argument against sewage irrigation must be admitted to want evidence from experience.
The third criticism appears to be true.
The land may become swampy and the adjacent wells poisoned, and disease (ague, and perhaps diarrhœa and dysentery) be thus produced. But this is owing to mismanagement, and when a sewage farm is properly arranged it is not damp, and the wells do not suffer.[153]
[153] ‘Practical Hygiene.’