Most fish poisonings occur from eating fish that normally are considered to be safe to eat. However, fish can become poisonous at different times of the year because of their consumption of poisonous algae and plankton (red tide) that occur in certain locations. The signs and symptoms of red tide paralytic shellfish poisoning are tingling and numbness of the face and mouth, muscular weakness, nausea and vomiting, increased salivation, difficulty in swallowing, and respiratory failure. Primary treatment is directed at evacuating the stomach contents as soon as possible. If the patient has not vomited, select the appropriate method to remove the stomach contents by either syrup of Ipecac or gastric lavage. If respiratory failure develops, support ventilation and other life-sustaining systems as needed. Examples of fish that are known to be poisonous AT ALL TIMES are shown in figure 5-1. The symptoms of shellfish and fish poisoning are tingling and numbness of the face and mouth, muscular weakness, nausea and vomiting, increased salivation, difficulty in swallowing, and respiratory failure. Primary treatment is directed toward evacuating the stomach contents. If the victim has not vomited, cause him to do so. Use syrup of Ipecac, gastric lavage, or manual stimulation; then administer a cathartic. If respiratory failure develops, give artificial ventilation and treat for shock. INHALATION POISONS In the Navy, and in other industrial settings in general, inhalation is the most common route of exposure to toxic substances. The irritants and corrosives mentioned in tables 5-2 and 5-3 are more often a source of poisoning by means of inhalation rather than by ingestion. An inhaled poison can act directly on the upper respiratory tract or lungs with immediate, delayed, or chronic effects, or the substance can use the pulmonary system to gain entry into the body, be absorbed into the blood, and cause toxic effects (systemic toxicity) at a distant site of action. The handling of large quantities of petroleum products (fuel oil and gasoline, in particular) constitutes a special hazard, since all of these products give off hazardous vapors. Other poisonous gases are by-products of certain operations or processes: exhaust fumes from internal combustion engines; fumes or vapors from materials used in casting, molding, welding, or plating; gases associated with bacterial decomposition in closed spaces; and gases that accumulate in voids, double bottoms, empty fuel 5-7 Toxin Source C i g u a t o x i n ( c h o l i n e r g i c effects) tends to be found in fish from coral reefs, including barracuda, grouper, red snapper, parrot fish Scombrotoxin (histamine-like reaction) tuna, bonito, skipjack, mackeral, mahi mahi Saxitoxin ( n e u r o l o g i c effects) bivalve shellfish (mussels, clams, scallops) accumulate toxin from dinoflagellate during red tides causing A paralytic shellfish poisoning@ *Tetrodotoxin (neurotoxin) *Neurotoxin bacteria found in puffer fish, California newt, eastern salamander Moray eel * toxic at all times Table 5-4.—Examples of Toxins from Fish Known to be Poisonous PUFFER TRIGGERFISH PARROT FISH PORCUPINE FISH FILEFISH SURMULLET OR GOATFISH SURGEONFISH HM3f0501 Figure 5-1.—Poisonous fish.