Natural poisons relative toxicity

The toxic nature of fluoride ion, F, is not confined to its presence in HF. It is toxic in soluble fluoride salts, such as NaF. At relatively low levels, such as about 1 ppm, used in some drinking water supplies, fluoride prevents tooth decay. At excessive levels, fluoride causes fluorosis, a condition characterized by bone abnormalities and mottled, soft teeth. Livestock are especially susceptible to poisoning from fluoride fallout on grazing land as a result of industrial pollution. In severe cases, the animals become lame and even die. 

Despite a relatively fast clearance of formaldehyde from the body, toxic effects may develop in exposed individuals, particularly in cases of acute oral poisonings which quickly overwhelm the body s natural mechanisms to metabolize formaldehyde (particularly via formaldehyde dehydrogenase see Figure 2-3). There is no standard method or practice to enhance the elimination of the absorbed dose of formaldehyde (Aaron and Howland 1994 Ellenhom and Barceloux 1988). 

While the CIA scoured the world in search of little-known poisons, its British and Canadian counterparts appear to have devoted their energies to refining poisons already discovered. Little is known of the exact nature of allied research in this field, although a report to the American House of Representatives did reveal that scientists at Fort Detrick had collaborated with Canadian counterparts in the early 19 5 os in attempts to isolate the paralytic poisoning in man often caused by eating toxic clams and mussels .32 By 1954, the two groups of scientists had extracted the poison in a relatively pure form . 

These substances in general exhibit low to intermediate order of toxicity in experimental animals. The severity of effects, however, depends on the nature of the species and also on the route of administration of the substance into the body. In humans, there is no reported case of poisoning. These substances have very low vapor pressure and are nonvolatile. The risk of inhalation is, therefore, very low. Also, any skin absorption or dermal route of entry of the pure material should be relatively insignificant. Accidental ingestion of a large dose, however, can be dangerous. 

Saxitoxin, the best known example of this group, is a potent neurotoxin found in shellfish such as mussels, clams, and scallops. Saxitoxin is a sodium channel-blocking agent and is more toxic by inhalation than by other routes of exposure. Unlike oral intoxication with saxitoxin (paralytic shellfish poisoning), which has a relatively slow onset, inhala-tional intoxication with saxitoxin can be lethal in a few minutes. Saxitoxin could be used against our troops as an antipersonnel weapon, but because it cannot currently be chemically synthesized efficiently, or produced easily in large quantities from natural sources, it is unlikely to be seen as an area aerosol weapon on the battlefield. 

Although the toxic effects of industrially produced aromatics have generally been well investigated, relatively little is known in many instances about the numerous poisons which occur naturally. Highly toxic natural aromatic poisons are, for example, aflatoxin Bi, which is produced as a metabolic product of Aspergillus flavus, and colchicine, obtained from the meadow saffron. 

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