Risk characterization

With information about the dose-response and exposure features of the substance, the risk can be characterized. Risk characterization is the process of estimating the probable incidence of an adverse health effect to humans who are under the circumstances of exposure. When every data is available, risk characterization should be based on human data. However, frequently human data is fragmented, incomplete, or even lacking. Thus, extrapolations are made from dose-response relationships...

Food Additives Colors and Flavors

For some consumers, processed food conjures up images of a food dead of nutrients and stripped of vitamins and fiber, and replaced with chemicals and worthless filler, or technology toying with nature in the name of profit. From the beginning of time, humans have invented ways to preserve food after harvest and slaughter to make it last longer, be more palatable, and, in recent times, be more readily available for use. Fire and root cellars were among the first forms of food processing humans...

Study questions and exercises

Distinguish between intentional and incidental food additives. Provide a few examples of each and describe how incidental additives get into foods and why intentional additives (function of additives) are added to foods. 2. Discuss how the Delaney Clause has impacted on the use of food additives in foods and the implication this clause has on safety evaluation of additives. Put into perspective the benefits and risks of additives in foods. 3. List the common food-preservation techniques and...

Us food laws

The original 1906 Food and Drugs Act contained two prohibitions only, which remain as part of the current law. The first forbids the marketing of a food containing any added poisonous or deleterious substance that may render it injurious to health. The second forbids the marketing of food containing nonadded toxicants that make them ordinarily injurious to health. The FDA had the burden of proving that a food was adulterated, and there was no required premarket approval. The act has been...

Ergot alkaloids and ergotism

Mycotoxicoses have been known for a long time. Ergotism occurred in the Middle Ages, around the 14th century in Europe. Ergot is a fungus, Claviceps purpurea, that grows on rye, and the consumption leads to intoxications and episodes of hallucinations, delirium, and convulsion and causes arteriolar spasms and gangrene. The gangrenous effects are associated with alkaloids that are partial a-adrenergic agonists and promote vasoconstriction, and the hallucinogenic effects are because the ergot...

Oral ingestion studies

Under normal situations, the oral route is usually the means by which toxicants from food enter organisms. Through industrial exposures or other rare situations, toxicants from foods may enter organisms by inhalation as a dust or vapor suspension in the air or percutaneous (dermal) penetration, respectively. The toxicologist selects the experimental route to test the bioactivity of a chemical based on the common route of exposure for the substance. Selection of the route of exposure is...

Antibiotic resistance

Pathogenic bacteria that have become resistant to antibiotic therapy are an increasing public health problem. For example, tuberculosis, gonorrhea, malaria, and ear infections in children are just a few of the diseases that have become hard to treat with antibiotic drugs. Part of the problem is that microorganisms that cause infections are extremely hardy and can develop ways to endure drugs meant to kill or weaken them. This antibiotic resistance (antimicrobial resistance or drug resistance),...

Food Intolerance and Allergy

According to some surveys, 20 to 25 of people in the U.S. are allergic to certain foods. Self-reported information based on changes in dietary habits to accommodate a food problem is likely to be mostly erroneous. Often, patients who say they have a food allergy avoid a food and never seek medical advice. Diagnosis of food allergies is overworked, poorly defined, and misused. There are many misconceptions about food allergies, such as understanding of the causes of food allergies and their...

Classes of Carbohydrates

Monosaccharides Simple sugars (galactose, fructose, glucose) Disaccharides Sucrose, lactose, maltose Polysaccharides Digestible starch, dextrins, indigestible starch If healthy population groups around the world are studied, there are relatively few illustrations of toxic effects associated with carbohydrate intakes. If sufficient food is available, population groups whose diets consist mostly of carbohydrates do not suffer adverse effects. Some short-term effects such as intestinal problems...

Storage Sites Plasma Proteins

Effect Food Irradiation

Substances found in blood or the vascular compartment bind reversibly with plasma proteins such as albumin, globulins, glycoproteins, lipoproteins, and more specifically transferrin and ceruloplasmin. Figure 8.9 shows a typical electrophoretic pattern of plasma proteins and depicts where various substances are likely to bind. Albumin can bind many substances and has a propensity for acidic compounds. More alkaline compounds are likely to bind with lipoproteins and glycoproteins. The binding is...

History of food irradiation

As noted in Table 18.1, the benefits of ionizing radiation have been known since 1905. In addition to its potential to irradiation can be used to eliminate pests such as the screw worm fly, which preys on cattle, the Mediterranean fruit fly, and the tsetse fly, by the release of sterile insects. Worries about nuclear weapons, combinedwithanantiprogressideology, began to hinder food irradiation research afterthe war. Althoughthere wasatthat time an adequate supply of gamma rays, the high-energy,...

Section I Fundamental Concepts

Chapter 1 An Overview of Food and Nutritional Toxicology Defining the Terms and Scope of Food and Nutritional Toxicology Toxicology Food and Nutritional Toxicology Toxicants in Foods and Their Effects on Nutrition Nutrients Naturally Occurring Toxicants Food Additives and Contaminants Impact of Diet on the Effects of Toxicants Study Questions and Exercises Recommended Readings Chapter 2 General Principles of Toxicology Phases of Toxicological Effects Exposure Phase Toxicokinetic Phase...

Products of the maillard reaction

In the Maillard reaction, reducing sugars (pentoses > hexoses) condensate with amino acids, producing a mixture of insoluble dark-brown polymeric pigments, termed melanoidins. Aldoses and ketoses react with aliphatic primary and secondary amines of amino acids and proteins to form -glycosides, which readily dehydrate to Schiff's base by the Maillard reaction (Figure 19.4). This is the basis for the well-known nonenzymatic browning reaction. In the early stages of the reaction, premel-anoidins...

Toxicants in foods and their effects on nutrition

Potential sources of toxicants in food include nutrients, natural food toxicants, contaminants, and chemicals or substances intentionally added to food (food additives). One usually does not relate the ingestion of a specific nutrient with concerns about the toxicity of that nutrient. However, intakes of essential dietary chemicals from zero to excessive produce responses, from lethal because of nutrient deficiency to an optimal health response and back to lethal because of intolerably high...

Analytical strategies

Analytical strategies for epidemiology include cross-sectional, prospective, and retrospective studies. Such strategies are often initiated following a sequence of descriptive studies. They are more informative than descriptive strategies however, they are expensive to run and time consuming to conduct. These types of epidemiology strategies have been used to obtain results that are used in safety evaluation of regulated products and provide the scientific base for governmental regulations of...

Diet and biotransformation

The biotransformation of a toxic compound usually, but not always, results in detoxification. It can, however, lead to the metabolic activation of foreign compounds. The effect of dietary constituents on the metabolism of foreign compounds has been the subject of intensive study for many years. More than two decades ago, the term toxicodietetics was coined for the study of dietary factors in the alterations of toxicity a term that was perhaps ahead of its time. There are a multitude of dietary...

Penicillia mycotoxins

Penicillium notatum is the organism which effectively blocks the synthesis of bacterial cell walls. About 40 years ago, a disease in swine and cattle was found to be due to consuming moldy corn. Swine died within a day after consuming about 0.5 lb of moldy corn LD50 6.6 mg kg of body weight, usually producing liver and kidney damage . The mold responsible was Pencillium rubrum, producing a mycotoxin known as rubratoxin. The two forms of rubratoxin are designated as A and B. Patulin is a...

Metabolism and Excretion of Toxicants

The amount of free plasma toxicant is a function of the toxicant's absorption, distribution, and elimination Figure 9.1 . In Chapter 8, a variety of factors that govern the absorption of toxicants in the gastrointestinal GI tract were discussed. This chapter focuses on factors that influence distribution and elimination of toxicants. Toxicants and other foreign compounds xenobiotics undergo metabolic transformation in the body. In many situations, the rate of metabolism is the primary...

Animal Toxins and Plant Toxicants

Toxicants are produced by a variety of animals and plants and are widely distributed throughout each kingdom, from the unicellular to the multicellular. There is striking diversity of chemical structures for toxic compounds found in nature, making classification based on structure difficult. The presence of toxicants in food may have come about because animals or plants evolved means of producing chemicals to protect themselves from predators, or insects, nematodes, microorganisms, or even...