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Risk, Toxicology, and Human Health G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 11 G. Tyler Miller’s Living in the Environment 13.

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Presentation on theme: "Risk, Toxicology, and Human Health G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 11 G. Tyler Miller’s Living in the Environment 13."— Presentation transcript:

1 Risk, Toxicology, and Human Health G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 11 G. Tyler Miller’s Living in the Environment 13 th Edition Chapter 11 Dr. Richard Clements Chattanooga State Technical Community College Dr. Richard Clements Chattanooga State Technical Community College

2 Key Concepts  Types of hazards people face  Methods of toxicology  Types and measurement of chemical hazards  Types and effects of biological hazards  Risk estimation, management, and reduction

3 Risk and Probability  Risk= Probability of exposure X Probability of Harm  Risk= Probability of exposure X Probability of Harm  Probability how risk is measured  Risk assessment  Risk management Fig p. 229

4 Hazards  Cultural hazards Unsafe working conditions, poor diet, drugs, drinking, driving, criminal assault, unsafe sex, poverty  Cultural hazards Unsafe working conditions, poor diet, drugs, drinking, driving, criminal assault, unsafe sex, poverty  Chemical hazards Chemical in the air, water soil and food  Chemical hazards Chemical in the air, water soil and food  Physical hazards Ionizing radiation, fire, earthquake, volcanic eruption, flood, tornadoes, and hurricanes  Physical hazards Ionizing radiation, fire, earthquake, volcanic eruption, flood, tornadoes, and hurricanes  Biological hazards Pathogens, pollen, and other allergens, and animals (such as bees, and poisonous snakes)  Biological hazards Pathogens, pollen, and other allergens, and animals (such as bees, and poisonous snakes) Fig p. 228

5 Toxicology  Toxicity: measures how harmful a substance is.  Dose: the amount of potentially harmful substance that a person has ingested, inhaled, or absorbed through the skin  Response: type and amount of health damage that results from exposure to a chemical or other agent  Acute Effect  Chronic Effect  Response: type and amount of health damage that results from exposure to a chemical or other agent  Acute Effect  Chronic Effect  Solubility: water soluble toxins and fat or oil soluble toxins  Persistence: resistance to breakdown  Chemical Interactions: synergistic interaction, and antagonistic interactions

6 Dose-affect Curve Fig p Size of dose 2.How often exposed 3.Who is exposed 4.How well the body’s detoxification system responds 5.Genetic makeup in regards to sensitivity (graph below)

7 DDT and Bioaccumulation (absorbed or stored in organs) and Biomagnification (through a food chain) Fig p. 231

8 Poisons: “The dose makes the poison” Paracelsus, 1540  Poison: LD 50 of 50 mg or less/Kg of body weight  LD 50: median lethal dose: the amount that in one dose kills exactly 505 of the animals in a test population in a 14 day period See Table 11-1 p. 232 Fig p. 231

9 How to Estimate Toxicity Case Reports: usually made by physicians; not very reliable; but do give clues to suggest further laboratory tests Epidemiological studies: health of people exposed to a toxin (experimental group) is compared to a statistically similar group of people not exposed to the toxin. Determine if there is any statistically significant association between exposure and health. Many problems with this technique.

10 How to Estimate Toxicity Laboratory experiments: most widely sued method: expose a population of live laboratory animals (usu. Rats and mice) to a measured dose of a specific substance under controlled conditions. Take 2-5 years and $200,000 – $2 million. More humane procedures increasing in use

11 Dose-Response Curves: acute toxicity  Dose-response  Nonthreshold  Threshold Fig p. 233

12 Chemical Hazards  Hazardous chemicals  Mutagens  Teratogens  Carcinogens  Neurotoxins  Hormonally active agents  Precautionary principle

13 Hormone Receptor Cell Normal Hormone Process Hormone Mimic Attach to estrogen receptor molecules Hormone Blocker Prevent natural hormones from attaching to their receptors Estrogen-like chemicalAntiandrogen chemical Figure 11-7 Page 234 Hormonally Active Agents (HAA’s)

14 Biological Hazards: Diseases  Nontransmissible disease: disease that are not caused by living organisms and not spread person to person.  Transmissible disease: caused by a living organism and spread person to person  Pathogens: infectious agents that cause disease include viruses, bacteria, fungi, and protozoans  Vectors: agents that transmit disease such as mosquito, fly, rat, etc.  Antibiotic resistance See Case Study p. 241  Malaria  AIDS

15 Figure 11-8 Page 236 Viruses HIV (AIDS) Hepatitis B Smallpox Ebola On this scale, a human hair would be 6 meters (20 feet) wide 1 micrometer Bacteria Vibrio cholerae (cholera) Myobacterium tuberculosis (tuberculosis) Treponema pallidum (syphilis) 6 micrometers Protozoa Plasmodium (malaria) 10 micrometers Pathogens

16 Figure 11-9 (1) Page 237 Genetic material Surface proteins Virus Structure

17 Virus Reproduction The viral genetic material uses the host cell's DNA to replicate again and again. Each new copy of the virus directs the cell to make it a protein shell. The new viruses emerge from the host cell capable of infecting other cells. This process often destroys the first cell. The virus attaches to the host cell. The entire virus may enter or it may inject its genetic material, or genome. Virus Cell membrane Host cell

18 In-text figure Page 238 Treating a colony of bacteria with an antibiotic kills most of the microbes. Sometimes, a bacterium has a genetic mutation that makes it resistant to the drug. When the colony grows back, all of its members will be descended from the drug-resistant survivor. Antibiotic Bacterial colony Mutation Drug-resistant bacteriumDrug-resistant bacterial colony Antibiotic Antibiotics attack harmless and harmful microbes. Drug resistance that develops in harmless bacteria may be transferred to harmful bacteria. One bacterium attaches itself to another, and a channel is opened between them in a process called conjugation. A copy of the genes that make the microbe resistant can then be passed from one microbe to the other. Harmless, drug-resistant microbe Conjunction Harmful drug-resistant microbe Harmful microbe Drug-resistant bacterial colony Antibiotic Antibiotic Resistance

19 Figure Page 240 North America 940,000 (20,000) Caribbean 420,000 (30,000) Latin America 1.4 million (80,000) Western Europe 560,000 (6,800) North Africa & Middle East 440,000 (30,000) Sub-Saharan Africa 28.1 million (2-3 million) Eastern Europe & Central Asia 1 million (23,000) South & Southeast Asia 6.1 million (400,000) East Asia & Pacific 1 million (35,000) Australia & New Zealand 15,000 (120) World HIV Distribution in 2001 (number of deaths due to AIDS)

20 Figure Page 240 HIV immune suppression facilitates active TB development AIDS can lead to job loss and poverty HIV/AIDS Malnutrition weakens body and may facilitate HIV transmission and progress Malnutrition may facilitate development of active TB MalnutritionTB TB can lead to job loss and malnutrition because of lack of money Active TB facilitates HIV replication and speeds up HIV progression Synergy between AIDS/TB/ Malnutrition

21 Malaria Life Cycle and Infection Fig p. 243

22 Deaths per 100,000 people < In-text figure Page 241 Global TB Epidemic

23 Figure Page 243 Malaria-free areasMalaria largely eliminatedMalaria transmission areas Worldwide Malaria Distribution

24 Risk Analysis  Risk analysis  Comparative risk analysis  Cost-benefit analysis  Risk management  Risk perception Fig p. 247


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