food toxicology group a. food toxicology: overview definition: food toxicology is the study of the...
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Food ToxicologyGroup A
Food Toxicology: Overview
Definition:
Food toxicology is the study of the nature, properties, effects, and detection of toxic substances in food, and their disease manifestation in humans.
Introduction
Historical background
Historical Background
“All substances are poisons, there is none which is not a poison. The right dose differentiates a poison from a remedy” ----Paracelsus (1493-1541)
Percival Pott
Orfila Father of modern toxicology
Developed methods to quantify poisons
Causes of Food Toxicity
3 types
Biological
Chemical
Physical
Causes of Food Toxicity
Bacteria and Viruses
Parasites
Fungi
Allergens
Example
Compylobacteriosis
Causes: Compylobacter jejuni
Diarrhea, vomiting and abdominal pain
Carrier: Raw poultry, Raw milk, undercooked poultry, Animal feces
Intrinsic Toxins
Present naturally in the food
Reduction by the suitable processing
Requires careful Food selection
For example, solanine is present in green part and sprouts of potatoes.
Intrinsic Toxins
Different categories of toxin depending upon its harmful effect
Goitrogens:
Direct effect on thyroid gland and cause goiter
Cassava beans contains these toxic compounds
Soaking, prior to cooking, can detoxify food.
Tannins:
Causes astringent and bitter taste
Carcinogen and Genotoxic effect
Careful selection of food can reduce chances of intoxication
Intrinsic Toxins
Phytoestrogens:
Non steroid compound
Structural similarity with steroidal which is steroid.
Food source may be rice, apples sesame seeds etc.
Cause cancer, disorders in reproductive system and osteoporosis
Phytates:
Food source are walnuts, paenuts and brown rice
Binds with iron to cause anaemia
Intrinsic Toxins
Antivitamins:
Replaces vitamin K due to structural similarity
Works anticoagulant of proteins
Extrinsic Toxins
Added externally either during processing or after processing
Contamination
Fungal toxins:
Aspergillus spp, Fusariuam spp, Penicillium spp.
Aflatoxins:
Aflatoxicosis
Produced by Aspergillus spp.
Sources are nuts, rice, meat, cottonseed
Carcinogenic
Extrinsic Toxins: Bacterial Toxins
Bacillus cerues:
Present in soil, dust and water
Produce a toxin “ cereulide”
Carrier is poorly cooked food
Causes nausea, abdominal cramps and vomiting
Clostridium perferingens
Present in soil and tract of human and animal
Produces “ lecithenase”
Carriers are turkey, chicken and beefs
Extrinsic Toxins: Chemical Toxins
Fertilizers:
Residues are present in food
Soil acidulation
Heavy metal accumulation
May present due to fertilizers residue or nearby industrial waste
Cadmium
Fluorine
Zinc
Calcium- low toxic
Principals of Food Toxicology
Food Toxicology
Food toxicology is concerned with assessing the injurious effects on living systems of chemicals present in foods and feeds.
Examine adverse effects ranging from acute to long-term
Naturally occurring or added by the environment
Toxicants
A poison or toxicant is the chemical that is harmful to living organisms because of its detrimental effects on tissues, organs, or biological processes
Four factors influence toxicity:
The toxic substance itself
The matrix in which it is present
The circumstances of exposure
The organism and its environment.
Classification of Toxicants
Heavy metals
Microbial toxins
Pesticides
Mushroom toxins
Plant toxins
Animal toxins
Food Allergens
Cyanides
Toxicology Paradigm
Toxicokinetics
Toxicokinetics describes the fate of toxic compound in the body.
Absorption
Ditribution
Biotransformation
Excretion of Toxic compounds
Sometimes called as Pharmacokinetics
Toxicokinetics
Toxicodynamics
Toxicodynamics describes the determination and quantification of the sequence of events at the cellular and molecular levels leading to a toxic response to an environmental agent
Sometimes referred to as pharmacodynamics.
Toxicokinetics VS Toxicodynamics
Toxicity Testing
To estimate the levels of the substance to which the population is exposed.
Acute Toxicity: to determine the level of the substance which induces mortality in laboratory animals.
Genetic Toxicity: to determine the tendency of the substance to induce mutations in the test organism.
Metabolism: to gain both a general and a quantitative understanding of absorption, biotransformation and disposition of the toxic substance
Difference Between Allergies and Toxic Reactions
Toxic effect is directly the result of the toxic chemical acting on cells
Allergic responses are the result of a chemical stimulating the body to release natural chemicals which are in turn directly responsible for the effects seen.
Most Common Food Allergens
Routes of Toxic Exposure
Ingestion
Toxics present in food items, cosmetics, household products
Inhalation
Aerosols, toxic gases, vapors
Surface absorption
Poison, ivy, oak, cosmetics
Injection
Intentional injection of illicit drugs, stings/bites
Routes of Toxic Exposure
Ingestion
Common agents:
Household products
Petroleum-based agents
Cleaning agents
Cosmetics
Drugs, plants, or foods
Absorption occurs in the
stomach and small intestine.
Sub-disciplines of Toxicology
Analytical toxicology
Clinical toxicology
Forensic toxicology
Industrial (occupational) toxicology
Environmental toxicology
Regulatory toxicology
Dose-Response Relationship:
Fundamental and essential concept.
The higher the dose, the more severe the response.
Based on observed data from experimental animal, human clinical, or cell studies.
Dose-Response curve:
Dose-Response relationship is illustrated by Dose-Response curve.
LD50:
Graphical Representation:
Variation is Dose-Response curves:
There is variation in Dose-Response curves in following parameters:
Predictability
Potency
Margin of safety
Potency vs. Efficacy
Interaction of chemicals
Potency:
Potency Vs. Efficacy:
Interaction of Chemicals:
Interaction of chemicals occur in three ways:
Additive Effect
Synergistic Effect
Antagonism
Additive Effect:
Synergistic Effect:
Antagonism: