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Toxicology and Human Health Toxicology and Human Health • Risk and Hazards – Risk - the possibility of suffering harm from a hazard that can cause injury, disease, economic loss, or environmental damage Toxicology and Human Health • Risk and Hazards – Probability - a mathematical statement about how likely it is that some event will occur • Ranges from 0 ( absolute certainty of no risk) to 1 (absolute certainty of risk) Toxicology and Human Health • Types of Hazards – Cultural Hazards • Poor diet • Unsafe sex – Chemical Hazards • Harmful chemicals in air, water, soil, food Toxicology and Human Health • Types of Hazards – Physical Hazards • Ionizing radiation • Noise • Natural disasters – Biological Hazards • Pathogens • Allergens • Animals Toxicology and Human Health • Toxicology – Toxicology - the study of the adverse effects of chemicals on human health – Toxicity - a measure of how harmful a substance is Toxicology and Human Health • Toxicology – Pathways of Exposure • Inhalation • Ingestion • Absorption chemicals on human health Toxicology and Human Health • Toxicology – Dose and Response • Dose - the amount of a potentially harmful substance a person has ingested, inhaled, or absorbed • Response - the amount of damage to health per given dose Toxicology and Human Health • Toxicology – Types of Responses • Acute Response - an immediate or rapid harmful reaction to an exposure • Chronic Response - a permanent or long- lasting reaction to an exposure Toxicology and Human Health • Toxicology – Factors Affecting Dose and Response • Bioaccumulation - an increase in the concentration of a chemical in a specific organ at a level higher than would normally be expected Toxicology and Human Health • Toxicology – Factors Affecting Dose and Response • Biomagnification -an increase in the concentration of certain slowlydegradable fat-soluble compounds in organisms at successively higher trophic levels in a food chain Bioaccumulation and Biomagnification Toxicology and Human Health • Toxicology – Lethal Dose and Poison • Median Lethal Dose (LD50) - the amount of a chemical received in one dose that will kill exactly 50% of all test animals within a 14 day test period • Poison - a chemical with an LD50 </= 50 milligrams per kilogram of body weight Toxicology and Human Health • Toxicology – Methods of Determining Toxicity • Case Reports • Laboratory Investigations • Epidemiology Toxicology and Human Health • Chemical Hazards – Toxic Chemicals - substances that are fatal to > 50% of test animals at a given concentration Toxicology and Human Health • Chemical Hazards – Hazardous Chemicals - chemicals that cause harm by: • Being flammable or explosive • Irritating or damaging skin or lungs • Interfering/preventing oxygen uptake • Inducing allergic reactions of the immune system Toxicology and Human Health • Chemical Hazards – Mutagens - chemicals that cause random mutations • Radiation Toxicology and Human Health • Chemical Hazards – Teratogens - chemicals, radiation, viruses that cause birth defects during development of human embryo • PCBs • Thalidomide • Steroid hormones • Heavy metals Toxicology and Human Health • Chemical Hazards – Carcinogens - chemicals, radiation, viruses that cause/promote growth of malignant tumors Toxicology and Human Health • Chemical Hazards – Carcinogens • Major Sources – – – – Cigarette Smoke (30-40%) Diet (20-30%) Occupational Exposure (5-15%) Environmental Pollutants (1-10%) Toxicology and Human Health • Chemical Hazards – Impacts on the Immune System • Immune System - cells and tissues that protect the body from disease by forming antibodies to invading agents and rendering them harmless Toxicology and Human Health • Chemical Hazards – Impacts on the Immune System • Synthetic chemicals • HIV virus • Ionizing radiation Toxicology and Human Health • Chemical Hazards – Impacts on the Immune System • Weakening of immune system and attack by allergens, infectious bacteria, viruses, protozoans Toxicology and Human Health • Chemical Hazards – Impacts on the Nervous System • Components of the Nervous System – Brain – Spinal Cord – Nerves Toxicology and Human Health • Chemical Hazards – Impacts on the Nervous System • Neurotoxins - chemicals that attack nerve cells – – – – – Chlorinated hydrocarbons Organophosphate pesticides Formaldehyde Heavy metals Industrial solvents Toxicology and Human Health • Chemical Hazards – Impacts on the Endocrine System • Endocrine System - organs and tissues whose actions are coordinated by chemical messengers called hormones Toxicology and Human Health • Chemical Hazards – Impacts on the Endocrine System • Hormones control: – – – – Sexual reproduction Growth Development Behavior Toxicology and Human Health • Chemical Hazards – Impacts on the Endocrine System • Endocrine Disrupters – – – – – – – Undersized penises Low testosterone levels Hyperactivity Vaginal cancer Malformed testicles Retardation Endometriosis Toxicology and Human Health • Biological Hazards – Types of Diseases • Transmissible Disease - a disease caused by a living organism which can be spread from one person to another – Pathogens - disease-causing organisms • Bacteria - single-celled organism • Viruses - noncellular infectious agent • Parasites - (tapeworm) • Protozoa - (amoeba) Toxicology and Human Health • Biological Hazards – Types of Diseases • Transmissible Disease – Sources of Exposure • Air • Water • Food • Body fluids • Insects • Non-human carriers (vectors) Toxicology and Human Health • Biological Hazards – Types of Diseases • Seven Dealiest Transmissible Diseases – Acute Respiratory Infections • Bacteria, Viruses (4.7 million deaths) – Diarheal Diseases • Bacteria, Viruses (3.1 million deaths) • Dysentery Toxicology and Human Health • Biological Hazards – Types of Diseases • Seven Dealiest Transmissible Diseases – Tuberculosis • Bacteria (3.1 million deaths) – Malaria • Parasitic protozoa (Plasmodium) • 2.1 million deaths annually Toxicology and Human Health • Biological Hazards – Types of Diseases • Seven Dealiest Transmissible Diseases – AIDS • HIV (1.7 million deaths) – Hepatitis B • Virus (1 million deaths) – Measels • Virus (1 million deaths) Toxicology and Human Health • Biological Hazards – Types of Diseases • Seven Dealiest Transmissible Diseases – LDCs • Infectious diseases account for 42% of all deaths annual • 27,000 deaths per day due to infectious diseases Toxicology and Human Health • Biological Hazards – Types of Diseases • Nontransmissible Diseases – – – – – – Cardiovascular disorders Cancer Diabetes Malnutrition Bronchitis Emphysema Toxicology and Human Health • Biological Hazards – Types of Diseases • Tuberculosis – Bacterial Disease – Airborne droplets of body fluids spread by coughing, sneezing, talking, singing – 95% of all new cases occur in LDCs – Rapid reemergence Toxicology and Human Health • Biological Hazards – Types of Diseases • Tuberculosis – Causes of reemergence • Poor screening and control programs • Development of genetically resistant strains of bacteria to antibiotics • Population growth and urbanization • Spread of AIDS Toxicology and Human Health • Biological Hazards – Types of Diseases • Influenza – Viral Disease – Transmitted by body fluids or airborne emissions • Spanish Flu Epidemic - 1918-1919; killed 30 million people – Ebola • Transmitted by blood or body fluids Toxicology and Human Health • Biological Hazards – Types of Diseases • Rabies – Viral Disease – Transmitted by dogs, skunks, raccoons • AIDS – – – – HIV - kills body’s immune cells Unprotected sex Intravenous drug use Blood transfusions Toxicology and Human Health • Biological Hazards – Types of Diseases • AIDS Facts – India has highest number of HIV-positive people – 1996 - 36 million people were infected with HIV – Heterosexual transmission accounts for 90% of new HIV infections Toxicology and Human Health • Biological Hazards – Major Diseases in MDCs • Epidemiological Transition – Related to Demographic Transition – Transmissible diseases supplanted by nontransmissible diseases • Cardiovascular Disease (39%) • Cancer (24%) • Infectious Diseases (5%) • Accidents (4%) Toxicology and Human Health • Biological Hazards – Sexually-Transmitted Diseases • Exposure Pathways – – – – Sexual activity Mother to infant during birth Intravenous drug use Infected blood Toxicology and Human Health • Biological Hazards – Sexually-Transmitted Diseases • Bacterial STDs – Chlamydia – Gonorrhea – Syphilis • Viral STDs – Genital herpes and warts – Hepatitis B – AIDS Toxicology and Human Health • Risk Analysis – Steps • Risk Assessment • Comparative Risk Analysis • Risk Management • Risk Communication Toxicology and Human Health • Risk Analysis – Risk Assessment - Identifying hazards, estimating the probability that each hazard will occur, and estimating how many people may suffer serious harm Toxicology and Human Health • Risk Analysis – Risk Management - determining options about reducing or eliminating risks – Risk Communication - informing decision makers and the public about risks Toxicology and Human Health • Risk Analysis – Risk-Benefit Analysis - an estimate of the short- and long-term risks and benefits of using a particular product or technology Risk Analysis Toxicology and Human Health • Risk Analysis – Issues and Limitations • Depends on toxicology assessments that have scientific and economic limitations • Who does the analysis? • Who interprets the results of the analysis? • How are risk levels set? • Goals of risk analysis?