1. The keeping of animals.
2. The slaughtering of animals.
3. Other branches of industry in which animal matters or substances of animal origin are chiefly dealt with.
4. Branches of industry in which vegetable matters are chiefly dealt with.
5. Branches of industry in which mineral matters are chiefly dealt with.
6. Branches of industry in which matters of mixed origin (animal, vegetable, and mineral) are dealt with.
(3) It is important to inquire to what extent offensive trade effluvia are injurious to the public health. It is impossible to bring statistics to bear on the inquiry, as other influences, apart from occupation, can scarcely be eliminated. The term “injurious to health” is capable of a double interpretation. It might mean either serious damage to health, or the mere production of bodily discomfort or other functional disturbance by the offensive effluvia, leading by its continuance to an appreciable impairment of vigour, though not to any actual disease.
In the latter sense offensive effluvia have a deleterious effect on health. Such symptoms as loss of appetite, nausea, headache, occasionally diarrhœa, and general malaise are produced by effluvia of various kinds, but agreeing in being all offensive. “A condition of dis-ease or mal-aise is produced.”
There is little difficulty in proving bad effects on the workmen, though the invariable defence of manufacturers is an appeal to the condition of health of their workmen. The workmen only remain such so long as they are healthy, and as they become disabled they necessarily cease to rank among workmen. The decomposition of putrefying organic matters is unquestionably dangerous. The general doctrine of sanitation that filth is one of the chief factors in producing disease is certainly applicable to trade effluvia as well as to general sanitation. It has been alleged on behalf of such effluvia as chlorine sulphurous acid and tar vapours that they are useful disinfectants; but modern research has shown that disinfectants, in order to be of practical use, must be in such a concentrated condition that the air containing them is irrespirable. Probably such septic diseases as erysipelas are favoured by organic trade effluvia.
(4) The means available to prevent or minimise the nuisances arising from trade effluvia vary with the character of the processes. The general principles on which treatment must be founded depend, as Dr. Ballard points out, on a recognition of the following kinds of effluvia:—