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Lecture

ESSA10LEcture9.docx

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Department
Environmental Science
Course Code
EESA10H3
Professor
,,

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Description
During the lecturre we will come on formulas and everything needed on questions 1. Todays topic is TOXICOLOGY and RISK ASSESMENT Very basic What is Toxicology? Science that studies poisons. How they are produced? How they are removed from the environment? Where can they be find? How they affect the organism? That’s the study of poison . Tocicisty of some chemicals basically depends on 1) Chemical characteristics of the poison that are: • Polarity Electronegativity • Oxidation state: When we talked about arsenic 3 and 5 are different • Molecular weight • Dissociation • Solubility – Water soluble toxins: Inorganic chemical dissolve in water, difficult for them human cell. They surround the cell but they don’t enter – Fat soluble toxins: Organic chemical are dissolved in fats. Fat soluble cell easily enter the cell, that’s why they bioaccumalate. • Persistence of chemical: Some chemicals can break down easily, some stay persistence for years without much change. • Bioaccumulation • Biomagnification • Chemical interaction – Antagonistic effect: One chemical reduces the toxicity of another chemical eg. Vitamin A and E might reduce cacogenic effect for some chemicals. – Synergistic: 2 different chemicals taken up at the same time by a person increase the risk of a disease eg. Smoking and • Multiple chemicals – food additives, pesticides, air pollution Very rare human is exposed to one chemical, usually exposed to multiple chemicals. • Receptor: Anybody can be the receptor, any organisms that receive exposure or dose, this course focoused on human. Frequency of the exposure is important to know Age: Child or elder person General Health: can be more prone for some respeonses, even some people of same age or same general health can have different effect. • Dose: Amount of chemical that person takes up or been exposed too. Three major routes for exposure: Ingestion through food, water etc, greatest exposure 95% going through ingestion Inhalation about 10% Transfer through the skin: Industrial chemicals could be absobs through the skin 5% Three different types of doses: Acute Dose: one single dose, usually high dose received in short time Chronic Dose: continuous dose but low dose Long term dose: low dose but receive for long time. • Response Syptoms that can be measured Response can be divided into 2 groups: Non specific: No certain tissue is attacked, the whole system is attacked. Eg. Burning, everything is destroyed and also when Narcosis(drunk) effects nervous system, vision, liver or some other organs. No specific tissue that is effected Specific: We know the tissue. Two different type of responses: Acute: Rapid response or death Chronic : Delay response Every chemical is harmful at some level, Water is poison if u drink 3 litters or more at once, can cause every serious health effects. About 100 cups of coffee for some people can cause death. Or 100 pills of aspirin. Question is How much can cause harmful effect. Its really hard from where to start measuring toxicology, if we measure right after we are exposed then there will be no good result Measurement endpoint is easier to measure, we measure biomarkers such as hormones and protein marker thats tells about enzyme induction. Scientists usually do experiments on animals. These experiments help scientists to determine lethal dose ( LD 50). Lethal dose is amount of the chemical received as a single dose that will cause mortality of the 50% percent of the experimental animals in a period of 14 days. Case reports: Some family physician make reports about what sypotoms are noted, what are possible complicat
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