Foodborne disease outbreaks of chemical etiology in the United States, 1970-1974.

In the United States between 1970 and 1974 there was an increase each year both in the absolute number of foodborne diseases outbreaks of chemical etiology reported to the Center for Disease Control and in the proportion of these outbreaks in the total reported foodborne disease outbreaks. Nearly half (48.9%) of these foodborne disease outbreaks of chemical origin were caused by toxic fish or shellfish. Of the rest, 16.5% were caused by poisonous mushrooms, 10.9% by heavy metal poisoning, 7.2% by excessive use in food of monosodium glutamate (the etiologic agent of Chinese Restaurant Syndrome) and 16.5% by miscellaneous chemicals. Practices that contributed to the occurrence of these outbreaks included the inadvertent selection for consumption of toxic fish, shellfish, or mushrooms, storage of fish at improper temperatures, storage of acidic liquids in metal containers, and addition of excessive amounts of monosodium glutamate to foods. Commercially-processed foods were responsible for outbreaks of scombroid fish poisoning, shellfish poisoning, and heavy metal poisoning. Because outbreaks of chemical etiology due to contaminated commercial products do occur, prompt recognition and reporting of outbreaks to public health personnel are essential so that epidemiologic investigations can be conducted and effective control measures promptly initiated.