Carcinogens and Anticarcinogens in the Human Diet A Comparison of Naturally Occurring and Synthetic Substances (1996) / Chapter Skim
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1 Introduction
1 Introduction
Pages 19-34
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synthetic substances that are known or suspected to affect cancer risk. Al though many substances present in the food supply have been shown to increase cancer risks under certain conditions usually not the conditions encountered in consuming food others may, in fact, decrease risk.
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to gauge how often specific foods are consumed or to identify by recall those foods recently consumed. Concentrations of specific, known carcinogenic agents in the food supply can be determined by analytic techniques, such as chemical analyses for pesticide residues present in foods as consumed.
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Inferences about dietary cancer risks are complicates] by the fact that the human cliet is a highly complex mixture containing a large number of chemical substances that are mostly natural, but also some that are synthetic.
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In evaluating dietary cancer risks, it is important that this uncertainty be recognized anal, if possible, characterizecl. Epidemiologic studies suggest that a diet with excess fat and caloric intake levels increases risk for some cancers.
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citizen and compares the risk from these chemicals with synthetic chemicals that may also be present in the food we eat. Although much of the current concern about the risks of naturally occurring carcinogens is motivated by concern about the potential effects of bioactive natural chemicals, the committee addressed the broader comparison between natu rally occurring chemicals that may possess carcinogenic potential and other naturally occurring dietary carcinogens, such as alla toxin and other mycotox~ns.
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One significant operational difference, however, is that naturally occurring chemicals in the food supply are not subject to the same government regulations as manmade chemi cars, a fact that raises questions about their safety and role as a possible threat to the health and well being of an inclividual.
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Historically, in acIdition to serving as a major food source, they have served as a source of medicines, potions, amulets, poisons, and panaceas to alleviate pain and cure illnesses, enhance physical and sexual performance, or terminate a rival. A vast history of folk medicine exists basec!
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as general classes, differ in their chemical and physical properties? Can the principles and techniques used for the evaluation of the carcinogenic and toxic properties of synthetic chemicals be used in the evaluation of naturally occurring chemicals, As examples for comparing the characteristics of naturally occurring and synthetic carcinogens, the committee used peroxisome proliferators, nitrosa mines, hydrazines, phenolic antioxiclants, methylenedioxyphenyl (benzodioxole)
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Consider ably more research writ be required to iclenti* the comparative risks for cancer of naturally occurring chemicals ranked against manmade chemicals.
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. In addition to these naturally occurring chemicals, food of ten contains a number of synthetic chemicals, although at a far lower level and in less variety.
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INTRODUCTION 29 Table 1-1 Definitions Term Definition Examples Constitutive naturally occurring substances Substances synthesized by physiological and biochemical processes present in food organisms themselves Furano coumarins, isoflavanoids, phyto alexins, cutins, alkaloids Derived naturally Substances formed as a Polycyclic hydrocarbons, occurring chemicals result of the breakdown pyrazines, and hetero of constitutive chemicals cyclic amines that pro during stress, storage, processing, and preparation of foods Acquired naturally occurring chemicals Pass through naturally occurring chemicals Substances present by infection or spoilage caused by bacteria or fungi or passively acquired from the environment Materials present in animal products con sumed by humans Blat are derived from food eaten by an animal vice characteristic flavor of roasted and cooked foods-coffee, chocolate, nuts, meats, and brown ing products that add color and flavor to foods, such as toast and tawny port wine Aflatoxin B1 or botulism toxin, as well as chemi cats such as the residues of persistent pesticides no longer used but remaining in the soil Any seafood toxins sometimes present in shellfish, toxol in snake root, or aflatoxin, which can appear in cows milk, or arsenic (a car cinogenic, toxic metal found naturally in sea . · ~ water and marine micro organisms)
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The definition of carcinogen proposed by lARC is used in this report a carcinogen denotes any agent, exposure to which is cape ble of increasing the incidence of malignant neoplasia MARC 19931. The term exposure is restricted to mean the amount of a naturally occurring substance ingested orally in the human diet.
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indirect synthetic food additives that might be carcinogenic and provides compari sons with naturally occurring chemicals. Chapter 4 discusses methods for evaluating potential carcino
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1990a. Nature's chemicals and synthetic chemicals: comparative toxicology.
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INTRODUCTION 33 Some Naturally Occurring Substances Food Items ant] Constituents, Heterocyclic Aromatic Amines ant]
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