Lecture 1 2 ss-5


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  • What’s an enzyme? What’s an effector organ?\n
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  • What does LD50 mean? \nLD stands for "Lethal Dose". LD50 is the amount of a material, given all at once, which causes the death of 50% (one half) of a group of test animals. The LD50 is one way to measure the short-term poisoning potential (acute toxicity) of a material. \nToxicologists can use many kinds of animals but most often testing is done with rats and mice. It is usually expressed as the amount of chemical administered (e.g., milligrams) per 100 grams (for smaller animals) or per kilogram (for bigger test subjects) of the body weight of the test animal. The LD50 can be found for any route of entry or administration but dermal (applied to the skin) and oral (given by mouth) administration methods are the most common. \nWhat does LC50 mean? \nLC stands for "Lethal Concentration". LC values usually refer to the concentration of a chemical in air but in environmental studies it can also mean the concentration of a chemical in water. \nFor inhalation experiments, the concentration of the chemical in air that kills 50% of the test animals in a given time (usually four hours) is the LC50 value. \n
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  • High Risk vs Low Risk\n
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  • Aflatoxin - Wikipedia, are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, most notably Aspergillus flavus and Aspergillus ...\n
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  • The liver is the largest gland in the body and performs an astonishingly large number of tasks that impact all body systems. One consequence of this complexity is that hepatic disease has widespread effects on virtually all other organ systems. At the risk of losing sight of the forest by focusing on the trees, we will focus on three fundamental roles of the liver:・Vascular functions, including formation of lymph and the hepatic phagocytic system.・Metabolic achievements in control of synthesis and utilization of carbohydrates, lipids and proteins.・Secretory and excretory functions, particularly with respect to the synthesis of secretion of bile.The latter is the only one of the three that directly affects digestion - the liver, through its biliary tract, secretes bile acids into the small intestine where they assume a critical role in the digestion and absorption of dietary lipids. However, understanding the vascular and metabolic functions of the liver is critical to appreciating the gland as a whole. [http://www.vivo.colostate.edu/hbooks/pathphys/digestion/liver/]\n
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  • Central Nervous System, Peripheral Nervous System\nAtaxia - affects on muscular movement\n
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  • Matrix: the intercellular substance of tissue\nBioavailability: The ability of a substance that enters the body to be liberated from its environmental matrix (water, tissue, soil) and to enter the circulation is referred to as Bioavailability\n
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  • Lecture 1 2 ss-5

    1. 1. ToxicityThe amount of harm a chemical can cause istoxicity.Origin of “Toxic” is Greek for “bow” (toxon) wherearrows (shot by bows) were sometimes tipped withpoison.Global production of chemicals was 1 million tons in1930 and is now over 400 million tons.
    2. 2. How Poisons Work Poisons work by:-  Changing the speed of different body functions  Increase – heart rate, sweating  Decrease – breathing, metabolism Steps involved in Poisoning  Biochemical change  e.g. inactivation of an enzyme  Cellular change  e.g. increase in nerve activity  Physiological changes  Signs and symptoms seen and felt in the effector organ Biochemical mechanism of action may be specific or nonspecific.
    3. 3. Organization ofliving things:Atoms combine tomake molecules orcompounds whichcombine to form anorganelle (a tiny“organ” within thecell); these combineto produce enzymes,create new cells,build new tissue, etc.;and groups of thesame kind of tissuemake up an organ;then system thenorganism.
    4. 4. asweknowit.net edtech2.boisestate.eduCells and Tissues of the Human Body stephanierosebio156.blogspot.com
    5. 5. What is the only cell in the body that does not contain DNA?1. Bone cell2. Muscle cell3. White blood cell4. Red blood cell5. Sperm or egg cell
    6. 6. What is the only cell in the body that does not contain DNA?1. Bone cell2. Muscle cell3. White blood cell4. Red blood cell5. Sperm or egg cell
    7. 7. LC50: LethalConcentrationtest for acutetoxicity ofchemicals inwater and air.
    8. 8. Macromolecular Damage Toxicant Receptor: Macromolecule in body with which toxicant interacts.  Enzyme  Membranes  Proteins  Nucleic acid – chronic effects Reactive compounds can damage cellular proteins. Heavy metals – (sulfhydryl) denatures proteins
    9. 9. Hazards in the EnvironmentHazardous Substances may enter the environment by:1. Direct exposure to the source of contamination (e.g Love Canal).2. Direct discharge into air, water, or soil.3. Inadequate landfills.4. Environmental catastrophic events (e.g.: Donora, Pa & Cuyahoga River,OH).5. Ecologic catastrophic events (e.g.: algal blooms - affecting ecosystems).6. Dumping (roadside, forests, marshes, etc.)
    10. 10. Environmental Hazardsinclude medical waste dumping
    11. 11. Environmental Hazardsinclude electronic waste dumping
    12. 12. Environmental Hazardsinclude yard waste dumping
    13. 13. Characteristics of Hazardous Exposure1. Route – inhalation, ingestion, dermal2. Magnitude – concentration or dose3. Duration – minutes, hours, days, lifetime4. Frequency – daily, weekly, monthly, seasonally
    14. 14. Health Outcomes From Environmental Hazards Carcinogenicity - (e.g from benzene) Heritable genetic andchromosomal mutations - (ionizingradiation)Developmental toxicity - (cadmium)Reproductive toxicity - (lead)Acute toxicity - (mustard gas)Chronic toxicity - (carbon tetrachloride)Neurotoxicity - (mercury)
    15. 15. Introduction to Toxicology Toxicology is the study of poisons.  Science dealing with poisons and their effects and with antidotes Toxic – poisonous  Affected by or caused by a toxin or poison (acting as a poison) Toxicant – poison or toxic agent Toxicity – how poisonous
    16. 16. Toxicity Toxic Agents Non-toxic Agents All substances can be toxic at the right dose.National Library of Medicine Toxicology Tutor:http://sis.nlm.nih.gov/enviro/toxtutor.html
    17. 17. Environmental Science ActivityHPV Chemical Hazard Data Availability StudyActivity Part I Answer questions 1 - 17 in classActivity Part II Answer Questions 1- 10 for homework.
    18. 18. Classes of Toxicants Air pollutants – volatile (or suspended particles) Water pollutants – soluble or suspensions/ emulsions Solid State Pollutants – soil or objects, ie. Lead, radionucleides, UV Food Additives or contaminants Exposure in workplace Drugs – pharmaceuticals or abuse
    19. 19. Types of Toxicants Pesticides – Parathion, DDT, Chlordane Natural Toxicants – Aflatoxin (fungus) Organic Chemicals – solvents in paint, glue, etc. Metals – lead, mercury (water or air) Physical Toxicants – asbestos, coal dust
    20. 20. Types of Effects Tissue or organ disruption:  Neurological – direct nerve or neurotransmitter – psychoactive compounds, metals  Organ System – tissue destruction, chemical inhibition (through protein interference) Teratogenic : defects in development and growth; Mutagenic  Heritable genetic and chromosomal mutation – ionizing radiation Carcinogenic: normal cells transform into cancer cells; exposure to chemicals, tobacco, asbestos Reproductive: cervical cancer - Papilloma Virus. Prostate cancer-It occurs when cells of the prostate mutate and begin to multiply out of control. Hormone Disturbance: pituitary gland
    21. 21. General Toxicity Categories Respiratory  System affected – nose, trachea, lungs  Common symptoms – irritation, coughing, choking, tight chest Gastrointestinal  System affected – stomach, intestine  Common symptoms - Nausea, vomiting, diarrhea Hepatic – Liver  Main purifying organ of the body Renal  System affected – kidney  Common symptoms – back pain, urination
    22. 22. General Toxicity Categories Neurological  System affected – CNS (brain & spinal cord), PNS  Common symptoms – headache, dizziness, confusion, depression, coma, convulsion, ataxia Hematological  System affected – blood  Common symptoms – anemia (tiredness, weakness) Dermatological  System affected – skin, eye  Common symptoms – rashes, itching, redness, swelling Reproductive  System affected – ovaries, testes, fetus  Common symptoms – infertility, miscarriage
    23. 23. The way by which a toxin enters the body is referred to as the __________ of exposure 
1. Magnitude2. Route3. Duration4. Frequency
    24. 24. The human body functions as one whole system but we need to also understand the parts that make up the whole. The parts that make up all human body systems are (in order):1. chemical- tissue- cellular – organ – organ system2. cellular – organ system - tissue- organ – chemical3. tissue – organ system – chemical – organ – chemical4. chemical – cellular – tissue- organ – organ system
    25. 25. What is homeostasis?1 The ability of a system to regenerate blood cells.2.The ability to maintain static electrical current within the heart muscle.3. The ability of a system or living organism to adjust its internal environment to maintain a stable equilibrium.4. The ability of starfish to regenerate its appendages.
    26. 26. Factors Influencing Toxicity1. The TYPE OF AGENT  Benign: normal environmental factors  Therapeutic: aspirin, antibiotics, pharmaceuticals  Toxic: harsh chemicals2. The DOSE  Toxicity is inversely related to dose: toxicity =1/ dose; the smaller the dose required to produce the response, the more toxic is the chemical.
    27. 27. Factors Influencing Toxicity1. AGE2. GENDER3. CULTURE4. PERSON – large vs small; active vs sedentary; genetic predispositions5. TIME AND FREQUENCY (DURATION) OF EXPOSURE6. NUTRITIONAL STATUS - diet and exercise???7. HEALTH STATUS - healthy vs compromised
    28. 28. Factors Influencing Toxicity8. TARGET SYSTEM  CNS – nerve, neurotransmitters (metals)  Renal – kidney, (metals, polar compounds that stay in the blood)  Pulmonary – lung (air borne materials)  Dermal – skin (contact agents)  Hepatic – liver, (fat soluble material)  Genotoxic – DNA, carcinogens, mutagens9. ENVIRONMENT  Temperature  Light (cycle, intensity)  Air (flow rate, humidity)
    29. 29. Types of Toxicity Acute  Measured by the median lethal dose (LD50) observed during the first fourteen days  Dose that will kill 50 percent of a group of animals under stated conditions Subacute  Establish the minimal toxic and maximal tolerated dose as well as the possible role of accumulation and tolerance  14 to 21 days Chronic  Over 90 days  Different doses
    30. 30. Manifestation of Toxic Effects Factors Affecting Bodily Processes  External: extreme conditions?  Internal: How the toxin enters the body: Ingested, inhaled, or absorbed through the skin. Types of physical effects seen or felt (signs and symptoms) depend on the type of stress to which the body has been exposed.
    31. 31. Manifestation of Toxic Effects Common Non-specific Symptoms  Headache  Fever  Nausea  Vomiting  Diarrhea Techniques used to diagnose the actual causes of diseases  Physical: detectable signs  Biochemical: blood and urine tests  Immunological: immune system (white blood cell count)
    32. 32. Manifestation of Toxic Effects Homeostasis of the Body can be upset by:-  Physical agents  Chemical agents  Biological agents Body’s reaction to stress depends on:-  Nature of the agent  Degree of stress  Duration of stress Prolong and Intense stress result in failure of homeostasis and eventual disease.
    33. 33. Toxic Effects Toxic effects can be either:-  Reversible – cause no permanent damage  Irreversible – cause permanent damage Poison can affect one or more organ systems. Biochemical evidence is needed as conclusive evidence of toxic exposure and effect.