FOOD POISONING. The term food poisoning as used by public-health workers and bacteriologists does not include the deliberate addition to food of poisonous substances with criminal intent, nor yet individual idiosyncrasy or sensitisation to certain proteins such as those contained in strawberries, eggs, milk or shellfish. Food idiosyncrasy depends primarily on a peculiar condition of the human body rather than on any dangerous quality in the food itself. The various "deficiency diseases," such as beriberi, scurvy and perhaps pellagra and goitre which are due to the lack of some essential element in the diet, are also not usually considered as types of food poisoning.
The manifestations ordinarily grouped as food poisoning at the present time are those due to : (I) the presence of poisonous sub stances in healthy, untreated plant or animal tissues; (2) the in troduction into food by accident, or design, of more or less familiar organic and inorganic poisons; (3) the presence in the food of living pathogenic bacteria or other parasites; (4) the presence in the food of poisonous substances elaborated by the growth of various micro-organisms.
Certain normal plant and animal tissues contain substances poisonous to man, and when eaten may cause illness and death ; such are poisonous mushrooms and certain fish found in tropical waters. Fatal cases of oxalic poisoning from eating the leaves of the common rhubarb have occurred. Horses and cattle grazing free on the western ranges are frequently poisoned when forage is scanty and they resort to weeds and plants generally left untouched, such as the larkspur, the lupins, the water hemlock, and the death Camas. Poisonous weeds eaten by cattle may indirectly produce poisoning in man. The disease known to the pioneer settlers in parts of the United States as milk sickness was early recognized to be connected with the occurrence of trembles in milch cows, but its origin long re mained obscure. It is now believed that both trembles and milk sickness were due to a poisonous substance in the white snakeroot (Eupatorium) which was eaten by the cows when other pasturage failed.
Occasionally mineral poisons like arsenic and lead find their way by accident into food in the process of manufacture, as in the famous outbreak of peripheral neuritis in several of the Midland counties in England in 190o, involving at least 6,000 persons and causing about 7o deaths (see ADULTERA TION) . More recently the cocoa sold by an English firm contained a small amount of arsenic derived from the potassium carbonate employed in its manufacture. Long-continued action of food on containers may dissolve harmful metals such as lead, copper or tin. Tin poisoning from canned foods, although theoretically' possible, is so rare as to have little practical significance, doubtless partly because such tin as is dissolved is largely fixed in an in soluble form by the solid portions of the canned food and elimi nated directly from the body. Copper, although not a violent irritant, may have a highly injurious effect when absorbed during many years, as in the constant use of distilled liquors containing copper derived from the copper worm of the condenser ; cirrhosis of the liver (see LIVER) may be caused in this way. Lead, owing to its well-known cumulative effect on the human body, is an undesirable substance to come in contact with food or drink. As long ago as 1767 the local malady of Devonshire colic was shown by Baker to be due to the action of cider on lead vessels. Lead poisoning has also resulted from the frequent use of acid beverages in bottles with lead stoppers. When lead was generally used in glazes and enamels for cooking vessels, recognized poisoning from these sources sometimes occurred ; the enamelled ware at present in common use in England and the United States is lead free.
The use of food preservatives consti tutes a very difficult and important phase of the problem of the addition of poisonous substances to food. Numerous substances have been added to food intentionally for the purpose of prevent ing the growth of micro-organisms and consequent spoiling. Some food preservatives once widely used are now known to be poison ous for man as well as antiseptic for microbes, and have been generally discarded or prohibited. Such are formaldehyde and hydrofluoric acid and their derivatives. Regarding some other preservative substances there is great diversity of opinion among those who have given the matter most study. The use of boron and salicylic acid compounds is generally, but not universally, dis approved. Benzoic acid, sulphurous acid and sulphites are re garded by many hygienists as permissible in certain foods under controlled conditions. The differences of opinion emphasise the insufficiency of our knowledge. Until information commanding the respect of all competent experts is available, it is well to err on the side of caution and minimise the use of preservatives.
The practice of adding poisonous substances to food merely for the sake of altering colour or appearance has nothing to recom mend it. At the present time any danger of actual poisoning from colouring matter added to candy, pastries and the like is slight. In most countries the health authorities maintain a list of sub stances, such as certain coal-tar dyes, which are permitted, and prohibitory regulation is strictly enforced. In the United States no colours and no preservatives in foods are permitted unless they are deemed harmless. (See FooD, PURE, and ADULTERATION.) Bacterial Poisoning.—Food may serve as the vehicle for cer tain kinds of disease-producing bacteria and other parasites. In some instances the bacteria are exclusively of human origin and occur in or upon the food as the result of contact with sewage contaminated water or through handling by a carrier of disease germs, e.g., the contamination of oysters with typhoid bacilli present in polluted water and the contamination of milk by a typhoid carrier on a dairy farm. In other instances the bacteria present in the food are derived from an infection of the food animal. This second class of infections is especially important in any survey of food poisoning since the gastrointestinal symptoms produced are often sudden and violent; many of the most typical and best known mass outbreaks of food poisoning belong to this group. The nausea, vomiting and diarrhoea that characterize these attacks usually attract attention to some article of food eaten shortly before. An attack of this kind rarely terminates fatally, and the symptoms pass off within 24 to 48 hours, having little after effect. Such symptoms characterize acute toxic poisoning and though cooking may have killed the bacilli themselves it will in many instances have left unaltered the toxins to which they give rise. Often a history of illness in the slaughtered animal can be secured. Some of the most extensive outbreaks of meat poi soning in European countries have been traced to the use of meat from an animal noticed to be ailing and promptly killed by the thrifty peasant as an emergency measure.
The bacteria that cause this typical form of food poisoning be long for the most part to the Salmonella group of paratyphoid bacilli, organisms closely related biologically to the typhoid bacil lus, but distinguishable by laboratory tests. Within this group are several different species (e.g., B. enteritidis, B. aertrycke, B. suipestifer) that primarily cause disease in various domestic ani mals, but secondarily and occasionally give rise to food poisoning in man. Food poisoning from bacilli would probably be much more common than it is if foods were not usually cooked. These bacteria are killed by boiling, and the history of many attacks shows that, while parts of an animal eaten raw or partly cooked have given rise to illness, other portions cooked before being eaten have been quite innocuous. Sausages made from uncooked meat or internal organs (liver sausage, blood sausage, etc.) have been the cause of food poisoning in a disproportionately large number of cases. Unfortunately inspection of the meat before sale may fail to reveal any evidence of infection, so that protec tion against this form of food poisoning depends chiefly on (a) the selection of healthy animals for slaughter and (b) thorough cooking of all foods of animal origin.
Foods may be also contaminated with the bacilli under discus sion by rats and mice. These rodents suffer from natural infec tions with these bacteria and can become carriers. Rodent con tamination must always be reckoned a possibility in investigating outbreaks of this type.
Certain of the higher animal parasites occasionally enter the human body in contaminated food. The small roundworm (Tri chinella) that causes trichinosis is one of the best known. Thorough cooking is an effective safeguard.
One of the earliest established instances of poison ing due to the products formed by the growth of micro-organisms in food substances is the disease of ergotism so prevalent in the middle ages. Ergot (q.v.) is the poison formed by a fungus that grows on rye ; in times of famine the enforced use of rye that would not otherwise have been eaten led to much suffering and many thousands of deaths.
It was long believed that many instances of gas trointestinal disturbance (the typical food poisoning of the lay man) were due to the products of various micro-organisms found in partly spoiled or decomposed food. Definite chemical sub stances—ptomaines were incriminated, and the expression pto maine poisoning came for a time to play as large a part in popular self-diagnosis as "influenza" or "the grip." In point of fact pto maine poisoning, if it occurs at all, must be exceedingly rare. Ptomaines appear in food substances in the later stages only of putrefaction—after about a week. Alleged instances of "ptomaine poisoning" when investigated by modern methods may almost always be traced with greater plausibility to some other form of food poisoning.
The products of bacilli that have grown in food may in some instances be the cause of food poisoning, even when the bacteria themselves have been killed. The determination of this question presents great technical difficulties and has not yet been settled.
The most conspicuous and definite example of poisoning from a microbic product formed in food is botulism, a disease which is dealt with at length under that heading. Here it may suffice to note therefore that, although so serious when ex perienced, botulism is fortunately, of very rare occurrence and, further, can be more or less completely guarded against by the adoption of simple precautionary measures. Foremost among these are steps to ensure cleanliness in all foods subjected to preservative processes and, in the case of heat-preserved foods, to use so far as practicable temperatures high enough to destroy the most resistant spores of the infective germ. The majority of canned foods proved to contain botulism toxin give sensible evidence of spoilage. The botulism toxin, unlike the organism that produces it, is readily destroyed by boiling. The immediate rejection, without tasting, of any food showing signs of spoilage, and the re-cooking of canned foods before serving, constitute a second line of defence. If these precautions are followed, botulism already rare should become practically unknown.
treatises on Food Poisoning ; E. Sacquepee Bibliography.-General treatises on Food Poisoning ; E. Sacquepee Les Empoisonnements Alimentaires (1909) ; A Study of zoo Recent Outbreaks of Food Poisoning, by W. G. Savage and P. B. White pub. by the Medical Research Council (1925) ; E. O. Jordan Food Poison ing (Chicago, 1917) ; Savage Food Poisoning and Food Infections (192o) ; Savage Canned Foods (Cambridge, 1923). On Food Preserva tives: Otto K. Folin Preservatives and Other Chemicals in Foods: Their Use and Abuse (Harvard, 1914) ; the British Ministry of Health's report on Preservatives and Colouring Matter in Food (1924) . For the paratyphoid infections, see E. Hubener Fleischvergiftungen and Paratyphusinfektionen (Jena, 1910) ; Gerald Leighton Botulism (1923) . See also special articles in the Journal of Infectious Diseases. Chicago ; the U.S. Public Health Reports, Washington ; and the American Journal of Public Health; also the monograph Botulism, by Ernest C. Dickson, monographs of the Rockefeller institute for medical research, No. 8 (1918) . (E. O. J.)
