Chapter 17 Environmental Hazards and Human Health

1. Chapter 17 Environmental Hazards and Human Health

2. Bellringer- Core Case Study Questions After reading, answer questions in Journal (5-10 minutes) • What Facts in the article stood out or surprised you? • Did this article make you raise concern in your lifestyle? In what way/s? • What experimental research could be done to discover if the effects of BPA in baby bottles or food cans are safe or not?

3. Core Case Study: Are Baby Bottles and Food Cans Safe To Use? The BPA Controversy • Some synthetic chemicals act as hormone mimics and disrupt the human endocrine system • Excess estrogen effects on males • Feminization • Smaller penis • Lower sperm counts • Presence of both male and female sex organs

4. Core Case Study: Are Baby Bottles and Food Cans Safe To Use? The BPA Controversy • BPA (bisphenol A) • Estrogen mimic • In polycarbonates and other hardened plastics • Baby bottles and sipping cups • Reusable water bottles • Sports drink and juice bottles • Microwave dishes • Food storage containers • Liners of most food and soft drink cans

5. Core Case Study: Are Baby Bottles and Food Cans Safe To Use? The BPA Controversy • BPA leaches into foods and drinks • Even when containers not heated • 93% of Americans older than 6 have BPA levels above the threshold level set by the EPA • Higher in children and adolescents • Risks for infants, children, adults

6. Baby Drinking from BPA Bottle Fig. 17-1, p. 436

7. 17-1 What Major Health Hazards Do We Face? • Concept 17-1 We face health hazards from biological, chemical, physical, and cultural factors, and from the lifestyle choices they make.

8. Risks Are Usually Expressed as Probabilities • Risk • Probability of suffering harm from a hazard • Probability vs. possibility • Probability is important in assessing risk • Risk Assessment- Process of using statistical methods to estimate how much harm a particular hazard can cause • Risk Management- deciding whether or not to reduce risks to certain levels

9. Science: Risk Assessment and Risk Management Fig. 17-2, p. 437

10. We Face Many Types of Hazards • Biological: • Pathogen: an organism that causes disease in other organisms • Chemical • Natural Hazards (Physical)- • storms, earthquakes, volcanic eruption, etc. • Cultural- • unsafe working conditions, poverty, criminal assault, etc. • Lifestyle choices • Smoking, excessive drinking, poor food choices, etc

11. 17-2 What Types of Biological Hazards Do We Face? • Concept 17-2 The most serious biological hazards we fade are infectious diseases such as flu, AIDS, tuberculosis, diarrheal diseases, and malaria.

12. Some Diseases Can Spread from One Person to Another • Infectious disease • Pathogen invades the body and multiplies • Bacterial disease- spreads via bacterial organisms • Viral disease- takes over a cell’s genetic make up and copies themselves • Transmissible disease • Contagious or communicable disease • Infectious disease transmitted between people • Flu, tuberculosis, measles

13. Some Diseases Do Not Spread from One Person to Another • Non-transmissible disease • Not caused by another living organism • Does not spread • Ex: Heart Disease, most Cancers, asthma, diabetes • Incidents of infectious diseases and associated death rates have decreased since 1900 • Though, they still pose major health threats

14. Infectious Diseases Are Still Major Health Threats • Infectious diseases spread through • Air • Water • Food • Body fluids (feces, urine, blood, mucous, etc.) • Large Scale Outbreaks: • Epidemic- large outbreak in an area or country • Pandemic- global infectious disease outbreak • Resistance of bacteria and insectsto drugs and pesticides

15. Science: Pathways for Infectious Diseases in Humans Fig. 17-3, p. 439

16. Major Causes of Death from Infectious Diseases in the World, 2007 Fig. 17-4, p. 439

17. WHO Infectious Disease Report • In your assigned groups (6 groups) read your case study • Your group’s task is to create a public service announcement to raise awareness about your research topic • Inform the class about the health issue of research, include in your report: • Explanation of the disease type or issue (and examples if applicable) • Transmission pathways and risks • Local and/or global statistics • Suggested Exposure/risk avoidance • Include main Ideas from each paragraph in the case study • Each person must present and will be graded on CLARITY, DETAIL, and KNOWLEDGE CONFIDENCE • i.e- speak LOUD, give ample information, and DO NOT READ off of your paper! Case Studies- Pages 439-445

18. Science Focus: Genetic Resistance to Antibiotics Is Increasing • Bacteria: rapid reproduction, easily spread • Overuse of antibiotics • Overuse of pesticides

19. Science Focus: Genetic Resistance to Antibiotics Is Increasing • Methicillin-resistant Staphylococcus aureus (MRSA) • Resistant to most antibiotics • Symptoms of MRSA • How will it be controlled?

20. Case Study: The Growing Global Threat from Tuberculosis • One in ten will become sick with TB • Infection of the lungs, airborne spread • Extremely underreported • 1.8 million deaths each year, primarily in less-developed countries • Why is tuberculosis on the rise? • Not enough screening and control programs • Genetic resistance to a majority of effective antibiotics • Person-to-person contact has increased • AIDS individuals are very susceptible to TB

21. Lung Tissue Destroyed by Tuberculosis Fig. 17-5, p. 440

22. Viral Diseases and Parasites Kill Large Numbers of People • Influenza or flu virus • #1 Killer • HIV • #2 Killer • Hepatitis B virus (HBV) • #3 Killer • Emergent diseases:West Nile virus

23. Viral Diseases and Parasites Kill Large Numbers of People • Viruses that move from animals to humans • West Nile virus • Ecological medicine- new interdisciplinary field devoted to tracking down unwanted disease connections between animals and humans • Reduce chances of infection: • Wash your hands • Avoid touching your face • Avoid sick people

24. Science Focus: Ecological Medicine: How Humans Get Infectious Diseases from Animals • Ecological medicine • Human practices that encourage the spread of diseases from animals to humans • Clearing/fragmenting forests • Hunting • expanding suburbs closer to woodland areas • Legal and illegal trade of wild animals • Emerging infections • HIV • Avian flu • Hepatitis B • Lyme virus

25. Case Study: Global HIV/AIDS Epidemic • Acquired immune deficiency syndrome (AIDS) • caused by human immunodeficiency virus (HIV) • Many secondary infections • Allows for opportunistic diseases • No vaccine to prevent or cure AIDS • Expensive drugs—live longer • NOT a cure…

26. Case Study: Global HIV/AIDS Epidemic • 25 million deaths, so far • #1 killer globally of women 15-49 • Most prevalent in sub-Saharan Africa • Life expectancy dropped from 62 to 47 • Alters age structure of population

27. Case Study: Malaria — The Spread of a Deadly Parasite • Malaria • 1 in 5 people infected globally (mostly in poor-African countries) • Caused by parasite spread by Anopheles mosquitos (Plasmodium parasite) • Kills 1 million per year • 2013- successful vaccine found and undergoing testing • Other preventative measures: incecticide bed nets, GMO resistant mosquitos, spray DDT • http://www.cnn.com/2013/08/08/health/malaria-vaccine/

28. Global Outlook: Distribution of Malaria Fig. 17-6, p. 444

29. A Boy in Brazil’s Amazon Sleeps Under an Insecticide-Treated Mosquito Net Fig. 17-7, p. 445

30. We Can Reduce the Incidence of Infectious Diseases • Death rate is continuing to drop • More people getting vaccinated • Developing more treatments • Oral Rehydration Therapy- prevents death from diarrhea • Solution of boiled water, salt, sugar or rice • Very cheap (few cents/person) • Still in need of funding for medical research

31. Solutions Infectious Diseases Increase research on tropical diseases and vaccines Reduce poverty Decrease malnutrition Improve drinking water quality Reduce unnecessary use of antibiotics Educate people to take all of an antibiotic prescription Reduce antibiotic use to promote livestock growth Require careful hand washing by all medical personnel Immunize children against major viral diseases Provide oral rehydration for diarrhea victims Conduct global campaign to reduce HIV/AIDS Fig. 17-8, p. 445

32. 17-3 What Types of Chemical Hazards Do We Face? • Concept 17-3 There is growing concern about chemicals in the environment that can cause cancers and birth defects, and disrupt the human immune, nervous, and endocrine system.

33. Some Chemicals Can Cause Cancers, Mutations, and Birth Defects • Toxic chemicals • Carcinogens • Chemicals, types of radiation, or certain viruses the cause or promote cancer • Mutagens • Chemicals or radiation that cause mutations or increase their frequency • Teratogens • Chemicals that cause harm or birth defects to a fetus or embryo

34. Case Study: PCBs Are Everywhere—A Legacy from the Past • Class of chlorine-containing compounds • Very stable • Nonflammable • Break down slowly in the environment • Travel long distances in the air • Fat soluble • Bio-magnification • Food chains and webs • Banned in 1977, however high persistence has reserved them in the environment everywhere

35. Potential Pathways on Which Toxic Chemicals Move Through the Environment Can move through non-living and living environments Fig. 17-9, p. 447

36. Some Chemicals May Affect Our Immune and Nervous Systems • Immune system disruptors andneurotoxins • Arsenic • Methyl-mercury • Dioxins • PCBs • Arsenic • Lead • Many pesticides

37. Science Focus: Mercury’s Toxic Effects • Hg: teratogen and potent neurotoxin • Once airborne, persistent and not degradable • 1/3 from natural sources • 2/3 from human activities • Enters the food chain: • biomagnification • How are humans exposed? • Inhalation: vaporized Hg or particulates • Eating fish with high levels of methylmercury- 75% of all human exposure • Eating high-fructose corn syrup

38. Science Focus: Mercury’s Toxic Effects • Effects of Hg on humans • Damage nervous system, kidneys, lungs • Harm fetuses and cause birth defects • Pregnant Woman at highest level of risk

39. Solutions Mercury Pollution Prevention Control Phase out waste incineration Sharply reduce mercury emissions from coal-burning plants and incinerators Remove mercury from coal before it is burned Label all products containing mercury Switch from coal to natural gas and renewable energy resources Collect and recycle batteries and other products containing mercury Fig. 17-10, p. 449

40. Some Chemicals Affect the Human Endocrine System • Network of Glands that release hormones that regulate bodily systems and control sexual reproduction, growth, development, learning, behavior • Hormonally active agents (HAA’s) have similar shapes and bind to hormone receptors • Sometimes referred to as Gender Benders • Thyroid disruptors- growth, weight disorders, behavioral, brain disorders • BPA and Pthalates

41. Hormone disruptors Hormone Estrogen-like chemical Antiandrogen chemical Receptor Cell Hormone Mimic Normal Hormone Process Hormone Blocker Fig. 17-11, p. 449

42. 17-4 How Can We Evaluate and Deal with Chemical Hazards? • Concept 17-4A Scientists use live laboratory animals, case reports of poisonings, and epidemiological studies to estimate the toxicity of chemicals, but these methods have limitations. • Concept 17-4B Many health scientists call for much greater emphasis on pollution prevention to reduce our exposure to potentially harmful chemicals.

43. Many Factors Determine the Harmful Health Effects of a Chemical • Toxicology- study of the harmful effects of chemicals • Toxicity- measure of harmfulness • dependent on • Dose • Age • Genetic makeup • Multiple chemical sensitivity (MCS) • Solubility • Persistence • Biomagnification

44. Many Factors Determine the Harmful Health Effects of a Chemical • Response-damage to health from chemical exposure • Acute effect: immediate or rapid • Chronic effect: permanent or long-lasting

45. Science: Estimating Human Exposure to Chemicals and Measuring Their Effects Figure 17.12:Science. Estimating human exposure to chemicals and measuring the effects of that exposure are very difficult because of the many and often poorly understood variables involved. Question: Which of these factors, if any, might make you more vulnerable to the harmful effects of chemicals? Fig. 17-12, p. 452

46. Water pollutant levels Soil/dust levels Air pollutant levels Food pesticide levels Nutritional health ? Scientific measurements and modeling Overall health Lifestyle Predicted level of toxicant in people Personal habits Metabolism Genetic predisposition Accumulation Excretion Lung, intestine, and skin absorption rates Fig. 17-12, p. 452

47. Case Study: Protecting Children from Toxic Chemicals • Analysis of umbilical cord blood: significance • 287 chemicals detected; large majority were carcinogens, neurotoxins and teratogens • Infants and children more susceptible (3 reasons) • Eat, drink water, and breathe more per unit of body weight than adults • Put their fingers in their mouths • Less well-developed immune systems and body detoxification processes • Melamine- common chemical harmful to children • Food additive, cleaning products, building materials

48. Scientists Use Live Lab Animals and Non-animal Tests to Estimate Toxicity • Mice and rats • Systems are similar to humans • Small, and reproduce rapidly • Is extrapolation (estimating data) to humans valid? • Dose-response curve: median lethal dose (LD50) • Nonthreshold dose-response model • Any dosage causes harm that increases with dosage • Threshold dose-response model • Certain level of chemical must be reached to be harmful

49. Scientists Use Live Lab Animals and Non-animal Tests to Estimate Toxicity • More humane methods using animals: • Replace animals with other models • Computer simulations • Tissue culture and individual animal cells • Chicken egg membranes • Much cheaper alternatives^ • What are the effects of mixtures of potentially toxic chemicals?

50. Hypothetical Dose-Response Curve Showing Determination of the LD50 Fig. 17-13, p. 453