against it and has been often used to effect suicide. Poisonous varieties of fish seem more abundant in tropical waters than in temperate, but this is possibly because of the more general and indiscriminate use of fish as food in such localities as the Japanese and South Sea Islands. It is known that some cool-water fish are poisonous. The flesh of the Greenland shark possesses poisonous qualities for dogs and produces a kind of intoxication in these animals.[29]

Much uncertainty exists respecting the conditions under which the various forms of fish poisoning occur. One type is believed to be associated with the spawning season, and to be caused by a poison present in the reproductive tissues. The roe of the European barbel is said to cause frequent poisoning, not usually of a serious sort. The flesh or roe of the sturgeon, pike, and other fish is also stated to be poisonous during the spawning season. Some fish are said to be poisonous only when they have fed on certain marine plants.[30]

There is little definite knowledge about the poisons concerned. They are certainly not uniform in nature. The Fugu poison produces cholera-like symptoms, convulsions, and paralysis. It is not destroyed by boiling. The effect of the Greenland shark flesh on dogs is described as being "like alcohol." It is said that dogs fed with gradually increasing amounts of the poisonous shark's flesh become to some degree immune. Different symptoms are described in other fish poisoning cases.[31]

CHAPTER IV

MINERAL OR ORGANIC POISONS ADDED TO FOOD

Well-known mineral or organic poisons—"chemical poisons"—sometimes find their way into food, being either introduced accidentally in the process of manufacture or preparation, or being added deliberately with intent to improve the appearance or keeping qualities of the food.

ARSENIC

So powerful a poison as arsenic has been occasionally introduced into food by stupidity or carelessness. Arsenic has been found by English authorities to be generally present in food materials dried or roasted with gases arising from the combustion of coal, and in materials treated with sulphuric acid during the process of preparation. In both cases the source is the same: the iron pyrites, practically always arsenical, contained in the coal or used in making the sulphuric acid.

A celebrated epidemic of "peripheral neuritis" in the English Midlands in 1900 was traced to the presence of dangerous quantities of arsenic in beer. About six thousand persons were affected in this outbreak and there were some seventy deaths. The beer coming from the suspected breweries had all been manufactured with the use of brewing sugars obtained from a single source, and these sugars were found to have been impregnated with arsenic by the sulphuric acid used in their preparation, some specimens of the acid containing as much as 2.6 per cent of arsenic.[32]

The use of glucose, not only in beer, but as an admixture or adulterant in jams, syrups, candies, and the like, is open to serious objection unless the glucose is known to have been prepared with sulphuric acid freed from arsenical impurity. In fact, the use of any food material prepared by the aid of sulphuric acid is permissible only in case arsenic-free acid is employed.[33]

ANTIMONY

The cheaper grades of enameled cooking utensils in use in this country contain antimony, and this is dissolved out in noteworthy amounts in cooking various foods.[34] The rubber nipples used for infants' milk bottles also sometimes contain antimony.[35] Although the poisonous qualities of antimony are well known, there is little information about the toxic effect of repeated very minute doses. Recognized instances of chronic antimony poisoning are very rare. Further investigation is needed.

LEAD

The well-known poisonousness of lead and its compounds prevents, as a rule, the deliberate addition of lead salts to food substances, although it is true that lead chromate is sometimes used for imparting a yellow color to candy and decorating sugars.[36] Foods that are wrapped in foil, however, such as chocolate and soft cheese, contain traces of lead, as do the contents of preserve jars with metallic caps and the "soft drinks" vended in bottles with patent metal stoppers. Occasional ingestion of minute quantities of lead is probably a matter of little physiological importance, but since lead is a cumulative poison, frequent taking into the body of even very small amounts entails danger. Severe lead poisoning has been known to result from the habitual use of acid beverages contained in bottles with lead stoppers. Investigations made to determine the possible danger of poisoning from lead taken up from glazed and earthenware cooking utensils indicate that injury from this source is unlikely. The enameled ware in common use in this country is lead-free.

Objection on the ground of possible contamination has been raised to the use of solder for sealing food cans. Such objections have less weight than formerly owing to changes in the construction of the container, so that any contact of solder with the food is now minimized and to a large extent done away with altogether.

In consequence of the fact that many natural waters attack lead, the use of lead service pipes for wells, cisterns, and public water supplies has given rise to numerous outbreaks of lead poisoning. It is now generally recognized that water intended for drinking purposes should not be drawn through lead pipes.

A special liability to take lead into the stomach exists in persons working at the painters' trade and other occupations involving contact with lead and its salts. It has been shown that the eating of food handled with paint-smeared hands brings about the ingestion of considerable quantities of lead and, when long continued, results in lead poisoning. The risk of contaminating food with lead in this way can be greatly lessened by thorough cleansing of the hands with soap and hot water before eating.[37]

TIN

Special interest