Toxicology
- Define toxicology.
the field of science that helps us understand the harmful effects that chemicals, substances or situations can have on people, animals and the environment
The scientific discipline involving the study of actual or potential danger presented by the harmful effects of chemicals (poisons) on living organisms and eco- systems; of the relationship of such harmful effects to exposure; and of the mechanisms of action, diagnosis, prevention, and treatment of intoxications.
- What is a toxic agent and what are the main types (6)?
Any chemical substance natural or synthetic (gas, liquid, peptides, glycosides, venoms, etc.), which produces or may produce an adverse/harmful effect on biological systems(plants/animals/humans).
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- Of natural origin
- biological origin
- Chemical contaminants
- Food Additives
- Toxic agents generated during storage, processing or preparation of foods
- Others: Allergens; Endocrine disruptors.
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- Define Xenobiotic and provide three examples.
- (BIO-Life and XENO-external or foreign). “Unnaturally present in a biological system”.
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- Xenobiotics are chemical compounds that is foreign to a living organism but which are found in their tissues by external exposure to them (Air, water, food, environment, etc).
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- E.g. plant constituents, drugs, pesticides, cosmetics, flavorings, fragrances, food additives, industrial chemicals and environmental pollutants.
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- What is the NOAEL and why is it important in toxicology?
Non-Observed-Adverse Health Effec (NOAEL): Greatest concentration or amount of a substance found by experiment or observation which causes no detectable adverse alteration of morfology, functional capacity, growth, development of life span of the target organism under defined conditions of exposure.
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- Importance in risk assessment, human health protection, regulatory decisions and research.
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- It helps regulatory agencies, such as the U.S. Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA), establish permissible exposure limits or safe dosage levels for chemicals, drugs, and environmental contaminants.
- Define acute toxicity and chronic and sub-chronic toxicity.
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- Acute toxicity: Rapid (within 24 hrs.) onset of effects generally upon a single doce or exposure to the agent.
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- Chronic toxicity: Medium of long term toxicity ocurring after several doses or exposure to the agent.
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- sub-chronic toxicity: adverse effects caused by the repeated or continuous exposure to a substance or agent over a relatively short to intermediate duration of time
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Define the main phases of toxic action?
Exposure
Refers to the way in which an organism is exposed to potentially harmful chemical agent (or pathogenic microorganims and their toxins) in a specific time period.
- Absortion
Once a living organism is exposed to a toxic agent, the compound will enter the living system through on or more routes (Oral, Dermal, Ocular, Respiratory, Otic).
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- Distribution.
Once the toxic agent has entered the body it will be distributed by the the various physiological systems (circulatory, limphatic, intestinal) to organs, tissues, cells, cell organelles and nucleic acids.
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- Metabolic Processing.
As the toxic compound reaches organs and tissues, it will biochemically react with other molecules (enzymes, lipids, etc.) and, in many cases, metabolites will be produced. Sometimes such derivative compounds are more toxic than the original molecule. Other times, the enzimatic processes render it unactive or les toxic.
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- Excretion.
As the biochemical processes unfold within the body, the original molecule and/or its metabolites will be excreted to some degree by the kidneys, the intestines or the lungs
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- Define LD50
Median Lethal Dose (LD50): Statistically derived dose of a chemical or physical agent (radiation) expected to kill 50% of organisms in a given population under a defined set of conditions.
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- Explain a Dose-Response curve.
A Dose–Response (concentration–response) relationship is defined as the association between dose (concentration) and the incidence of a defined biological effect in an exposed population, usually expressed as percentage. Historically the defined effect was death. The classic dose–response or concentration–response relationship is shown.
- What is the risk assessment process and why is it important in toxicology?
A process intended to calculate or estimate the risk to a given target organism, system or (sub) population, including the identification of attendant uncertainties, following exposure to a particular agent, taking into account the inherent characteristics of the agent of concern as well as the characteristics of the specific target system.
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It provides a systematic and scientific approach to evaluating and managing the potential health risks associated with exposure to chemicals, drugs, environmental contaminants, and other hazards for decision making and prevention.
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- How is a risk assessment performed?
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To carry out a risk assessment, it is necessary to take into account the following aspects: 1. Hazard identification, 2. Hazard characterization, 3. Exposure evaluation and 4. Risk characterization.
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- Define Hazard characterization.
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Opción 1: Hazard characterization is the way to show the relationship between the levels of a certain toxic agent consumed (dose) and the probability of developing an adverse effect or reaction to this exposure (response).
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Opción 2: The qualitative and/or quantitative evaluation of the nature of the adverse health effects associated with biological, chemical and physical agents which may be present in food. For chemical agents, a dose-responses assessment should be performed; for biological or physical agents, a dose response assesment, a dose response assessment should be performed if the data are obtainable.
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- Define the stages of Risk Analysis.
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Risk assessment: process intended to calculate or estimate the risk to a given target organism, system or (sub) population, including the identification of attendant uncertainties, following exposure to a particular agent, taking into account the inherent characteristics of the agent of concern as well as the characteristics of the specific target system. It is an iterative process that requires updating as scientific information evolves.
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Risk management: Involves The evaluation of Risk at an aggregate level, that is, considerin many more factors then the “merely “technical” ones. Among them Social and economic factors.
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Risk communication: It is the action of communicating the risks found to both consumers and interested parties.
\n What is the difference between risk and hazard?
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The difference is that hazard is the agent that will cause adverse effects and risk is the probability that this will occur in a certain environment.
\n What is the difference between risk assessment and risk analysis?
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Risk assessment is considered the process where certain risk parameters are identified (hazard identification, hazard characterization, exposure evaluation and risk characterization). On the other hand, risk analysis is everything about research since it covers other aspects. in order to have results to communicate.
\n Give three adverse effects caused by cyanogenic glucosides.
- Neurological disorders
- Konzo
- Cretinism
- Goiter
- Growth retardation
- Tropical ataxic neuropathy (TAN)
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- Which are the main carbohydrates associated with flatulence and in what foods are they more abundant?
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The rafinnose family (RFO): 1. Raffinose: Trisaccharide (beans and other legumes) 2. Stachyose (soybeans, greenbeans, rapeseed and other legumes) 3. Verbascose (soybeans and legumes)
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- What is solanine and how can it be avoided in a human diet?
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It is a steroid alkaloid with two halves: a steroid nucleus (solanidine) and a side chain made up of sugars. And we can avoid from the diet with some strategies
1.- Use varieties with low capacity to synthesize glucoalcaloids (Solanine and Chaconine).
2.- Avoid stress during handling and storage.
3.- Avoid exposure to light as much as posible.
4.- Discard suspect products and/or peels which have turned very green during storage.
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- Cite at least four marine biotoxins and their adverse health effects.
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1.- Paralytic Shellfish Poisoning (PSP). (Saxitoxin)
Depression of the cardiac muscle and blocking of the sodium channels in nervous membranes.
Paralysis in the breathing system.
Trembling and numbing
2.- Diarrheic Shellfish Posioning (DSP). (Okadaic Acid, Yesotoxin)
Nausea, vomit, abdominal pain
Formation of tumors
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3.- Amnesic Shelfish Poisoning (ASP). (Domoic Acid)
Diarrhea, vomiting, and temporary loss of memory.
Brain damage and in severe cases, death.
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4.- Neurotoxic Shellfish Posioning. (NSP). (brevetoxins)
This toxin interact with specific receptors in the nervous system causing a series of abnormalities such as respiratory problems and epileptic-like seizures
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5.- Ciguatera Poisoning. (ciguatoxin)
Diarrhea, vomiting, headache, neurological harm.
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6.- Azaspiracid Poisoning.
Cause morphological Changes in the small intestine and stomach. Also, progressive paralysis and breathing problems.
7.- Tetradotoxin.
Blocks sodium channels in nerve cells thus preventing the transmission of nerve signals and causing paralysis.
8.- Other toxins
Pectenotoxins: They produce colon and lung toxic effects.
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