Ice is now very generally used for domestic purposes, especially in cities. As a means of maintaining low temperatures for the preservation of food materials it is extremely useful. Used in this way, it cannot possibly be a menace to health. If it is dangerous at all, it is only through the enormous quantities introduced into foods and drinks that it can by any possibility be a vehicle of disease.

319. Does Ice Ever Carry Disease Germs?

A general opinion prevails that water purifies itself from foreign matter on freezing. This does not appear to be strictly true. Both natural and artificial ice are not always free from living bacteria or other micro-organisms. This is made clear by various observers. Epidemics of disease have been attributed to contaminated ice, or frozen snow, upon evidence that appears to be fairly reliable. Ice that comes from rivers or ponds which are a receptacle for sewage or human dejecta is to be regarded with suspicion. On the other hand, the freezing of water tends to purify it through exclusion of foreign matter. More than this, only a small proportion of individual bacteria survive a freezing temperature, especially when this temperature lasts for a considerable period of time; and those that survive are regarded as being less virulent.

However, ice pollution may have other sources than the pond or river, among which may be named filthy workmen, the droppings of horses used on the ice field, and the dirty materials in which the ice is packed. Of course the washing of ice by pure water, or by its own melting, cleanses it from superficially attached matter. When everything is considered, however, public ice supplies cannot be regarded as safely sanitary, even in the case of artificial ice, which may be subjected to some of the same sources of infection as natural ice, and, because it is promptly used, may be more dangerous. The only ice that is sure to be sanitary is that which is made from pure water and is handled in a cleanly manner. Housewives should be advised that there is more or less danger in the promiscuous use of ice in drinks unless its source guarantees its purity. When used for cooling water, danger can be averted by setting a receptacle containing the ice into the water to be cooled, rather than putting the ice directly into the water. Such a precaution is worth while, even though the chances of the conveyance of disease by ice are rather small.