Toxicology The study of the effects of poisons

Toxicology The study of the effects of poisons is called Toxicology.

• Poisonous substances are produced by Plants ------ Phytotoxins Animals ------Zootoxins Bacteria-------Bacteriotoxins Fungus--------Mycotoxins Toxicant - the specific poisonous chemical. • Xenobiotic - man-made substance

Food toxicology • The study of the toxic effects of food and water on human being • Health disorders------optimum amount of food containing harmful substances • Natural constituents of the food (intrinsic) • Picked up by the food from farm to fork (extraneous) may fatal

Food Toxicity • Illness may be restricted to an individual Or a group of people • Intensity and symptoms of food toxicity depends upon Nature of contaminant Quantity Consumers immunity strength

Types of Toxic Effects • Death - arsenic, cyanide • Organ Damage - ozone, lead • Mutagenesis - UV light • Carcinogenesis - benzene, asbestos • Teratogenesis - thalidomide

Naturally occurring toxins in plant foods • Foods are complex mixture of thousands of chemicals which are their natural components • Excess may prove---toxicity hyper vitaminosis , sugar, fat • Plants ---natural source • Human body has developed built in mechanism for most intrinsic • Therefore chances of toxicity are rare • In case, such food –excessive quantities over a long period cause illness.

Accidental toxicity • It may occur by consuming food of plant origin due to ignorance of the consumer • Raw cashew nut---swelling • Fresh & poorly cooked cassawa tubers of some varieties • Among the toxic compounds in plants are protease inhibitors, hemoglutannins, cynogens, alergens, goitero genes, lytherogens

Hemogglutinins • Protease inhibitors, trypsin inhibitors and Hem 0 ----protonesious compounds present in legumes–poor digestibility. • Cerelas detoxified by soaking, germinating, steaming, fermentation • Fava Beans---Favism---- hemolytic anaemia

Goitrogenes • Turnip, radish, cabagge, • Occusionally consumption of larger quantities for extended period • Enlargment of thyroid • Cows feeding on ----secret goitrins in milk

Cynogenes • HCN poisoining, HCN + stomach acid ------CN • Peas, pulses, fruit kernels, (apricot )cassava, Lima beans

Other toxic compounds • Potaoes---solanine +Chaconine--exposed to sunlight for longer time----8 kg of potatoes at a time • Spinach, cashew, nuts, tea. Sesame seed----organic acid (oxlaic acid). It interferes Fe, Ca, Mg, Cu • Calcium oxalate --- kidney stones

Prevention & detoxification • Wild & unfamiliar plant should not be eaten • Consumption of bitter taste food should be avoided • All beans varieties should be soaked & cooked

Intrinsic toxins from animal origin • Animal protein---protein maluntrition---kwashiorkor • High protein diet---- calcium losses ---liver, kidney ill effects • Pesticide residues, antibiotics, hormones accumulate in the flesh---cancer

• Mad cow disease • fish

Toxicity –food procesing equipments • Metals enter the body through inhalation of polluted air (lead)/drinking water/food • Antemony, arsenic, zinc poisoining----galvenized iron or low quality enamel vessel • Acidic foods when cooked /stored formed salts

Effects of toxins • Effects humans through (ingestion, injection or contact) • Organism, tissue or pure toxin • Most are proteinaceous • Most are fairly stable at standard conditions • Ranges for p. H and temperature tolerance from toxin to toxin

Characteristics • • Non replicative Non infectious Non communicable Non transmittable (human to human) Nonvolatile Colorless Odorless, and Taste

Natural toxins in food Chemical Food source Hazard Allyl isothiocyanate Brown mustard, garlic Tumours Benzo(α)pyrene BBQ/smoked meats Stomach cancers Cyanides Bitter almonds, cashews, lima beans General toxicity Nitrosoamines Cooked meats Cancer Estragole Basil, fennel, Tumours Glycyrrhizic acid Liquorice Hypertension/ heart Hydrazines Cancer Raw mushrooms

Natural toxins in food Chemical Food source Hazard Myristicin parsley, carrots, pepper liver damage/death Oxalic acid spinach Kidney damage/death Saxitoxin Shellfish Paralysis/death Tannins & tannic acid Black tea, coffee, cocoa Cancers/ throat & mouth

Chemicals used to preserve food Chemical Use Ascorbic acid Antioxidant/antimicrobial BHA Antioxidant Calcium propionate Mold inhibitor EDTA Antioxidant Sodium benzoate Microbial inhibitor BHT Antioxidant Sodium nitrite Microbial inhibitor in meat Sorbic acid Mold inhibitor in cheese BHA= butylated hydroxyanisole BHT = butylated hydroxytoluene EDTA = ethylenediaminetetraacetic acid

Food Additives: • Any chemical added to a particular food for a particular reason during processing or storage which could affect the characteristics of the food, or become part of the food.

Such food ingredients are not additives • salt, sugar, flavourings, • minerals, spices or seasonings, • vitamins, packaging materials, • veterinary drugs & agricultural chemicals.

Uses of Additives • raises the nutrient value • prevents cancer causing agents from forming • anti caking agents • bleaching agents: dough conditioners • colouring agents • emulsifiers & stabilizers • as preservatives & prevent fats from rancidity • to slow growth of microorganisms

Classes of Additives • • Antimicrobial agents Antioxidants Artificial colors Artificial flavors and flavor enhancers Bleaching agents Chelating agents (which are used to prevent discoloration and flavor changes) Nutrient additives Thickening and stabilizing agents

Common Food Additives: • Ascorbic Acid: • used in cereals, cured meats & fruit drinks as an antioxidant, colour stabilizer or as a nutrient • Artificial & natural flavouring: • used in cereals, candy, gelatin, desserts, soft drinks &many other foods as copy/artificial of natural flavours

Additives… • Butylated Hydroxytoluene (BHT) • cereal, chewing gum, & potato chips as an antioxidant. It keeps oils from going rancid. • Gums: (Arabic, guar, locust bean) • used in beverages, candy, cottage cheese, dough, drink mixes, frozen pudding, ice cream, salad dressings as stabilizers & thickening agents

Legislation in World Type of Additive E Number Colouring Most begin with 1 Preservatives Most begin with 2 Flavourings Not numbered Antioxidants E 300 – 321 Emulsifiers and stabilizers E 322 and some numbers between E 400 and E 495 Sweeteners Most begin with 4 or 6

Measures of Toxicity • Toxicity of chemicals is determined in the laboratory • The normal procedure is to expose test animals • By ingestion, application to the skin, by inhalation, gavage, or some other method which introduces the material into the body, or • By placing the test material in the water or air of the test animals’ environment

Measures of Toxicity • Toxicity is measured as clinical “endpoints” which include • Mortality (death) • Teratogenicity (ability to cause birth defects) • Carcinogenicity (ability to cause cancer), and, • Mutagenicity (ability to cause heritible change in the DNA) • At this time we will discuss 2 measures of mortality – the LD 50 and

Measures of Toxicity: The Median Lethal Dose LD 50 The amount (dose) of a chemical which produces death in 50% of a population of test animals to which it is administered by any of a variety of methods mg/kg Normally expressed as milligrams of substance per kilogram of animal

Measures of Toxicity: The Median Lethal Concentration LC 50 The concentration of a chemical in an environment (generally air or water) which produces death in 50% of an exposed population of test animals in a specified time frame mg/L Normally expressed as milligrams of substance per liter of air or water (or

Primary Routes of Exposure to Pesticides There are three primary routes by which organisms are exposed to pesticides Oral Dermal Inhalation

Primary Routes of Exposure: Oral Exposure Any exposure to pesticide which occurs when the chemical is taken in through the mouth and passes through the gastrointestinal tract During oral exposure, although carried within the body, the pesticide is still outside of the body cavity

Primary Routes of Exposure: Dermal Exposure of the skin to a pesticide Most common route of human exposure With proper hygiene this type of exposure is generally not serious unless there is a specific, rapid toxicological effect (often eye effects) which is of concern

Primary Routes of Exposure: Inhalation Exposure Occurs when a pesticide is breathed into the lungs through the nose or mouth Significant route of exposure for aquatic organisms Not of toxicological concern until it crosses from the lung into the body (unless the chemical is corrosive)

Duration of Exposure Three terms are commonly used to describe the duration of dose(s) Acute Chronic Subchronic

Duration of Exposure: Acute Exposure Application of a single or shortterm (generally less than a day) dosing by a chemical If toxic symptoms are expressed, they are referred to as symptoms of “acute toxicity”

Duration of Exposure: Chronic Exposure Expression of toxic symptoms only after repeated exposure to a chemical in doses regularly applied to the organism for a time greater than half of its life-expectancy If toxic symptoms are expressed, they are referred to as symptoms of “chronic toxicity”

Duration of Exposure: Subchronic Exposure Toxic symptoms are expressed after repeated applications for a timeframe less than half the life expectancy of the organism – but more often than a single dose or multiple doses applied for only a short time If toxic symptoms are expressed, they are referred to as symptoms of “subchronic toxicity”