Presentation on theme: "17 TH MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT Chapter 17 Environmental Hazards and Human Health."— Presentation transcript:
17 TH MILLER/SPOOLMAN LIVING IN THE ENVIRONMENT Chapter 17 Environmental Hazards and Human Health
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.
Human Chemical Exposure We are exposed to numerous chemicals every day: environmental sources such as air and water pollution pesticides cleaning products food additives Some of these chemicals are threats to human health, but tracing exposures and determining what levels of risk they pose is a painstaking process. How do harmful substances enter the body, and how do they damage cells? In this chapter, we learn how dangers are assessed, what kind of regulations we use to reduce exposures, and how we manage associated human health risks.
Science: Risk Assessment and Risk Management Fig. 17-2, p. 437 Risk assessment and risk management are used to estimate the seriousness of various risks and how to reduce such risks. Question: What is an example of how you have applied this process today?
We Face Many Types of Hazards 1.Biological: Pathogens are organisms that causes disease in other organisms. 2.Chemical 3.Physical 4.Cultural 5.Lifestyle choices Write down two examples of each.
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.
Some Diseases Can Spread from One Person to Another, Others Cannot Infectious disease Pathogen invades the body and multiplies Transmissible disease Contagious or communicable disease Infectious disease transmitted between people Flu, tuberculosis, measles Nontransmissible disease Not caused by living organisms Heart disease, most cancers, diabetes Which of these are communicable? HIV Malaria Asthma Ebola Flu
Since 1950, death from infectious diseases have declined due to: Better health care Better sanitation Antibiotics Vaccines Vast Improvements…
However … Infectious Diseases Are Still Major Health Threats Infectious diseases spread through: Air Water Food Body fluids Epidemics and pandemics Resistance of bacteria and insects to drugs and pesticides
Science: Pathways for Infectious Diseases in Humans Fig. 17-3, p. 439
Major Causes of Death (CDC, 2005)
From the Centers for Disease Control and Prevention (CDC) (Current)
What are the major causes of death from infectious diseases in the world?
Major Causes of Death from Infectious Diseases in the World, 2007 Fig. 17-4, p. 439
Current Event and W.H.O. Information Blitz Homework (About 2 nights worth): Readings for Harkness on Thursday, Ebola. Active reading establishes your base score. Prompt for discussion already written. Read Core Case Study, p. 436; Science Focus, p. 442 Review Questions 2 and 3, p. 463 Reading as appropriate
Case Study: Malaria — The Spread of a Deadly Parasite (1) Malaria Caused by Plasmodium sp. carried by Anopheles mosquitoes Tropical and subtropical regions Africa Central and South America Southeast Asia
Case Study: Malaria — The Spread of a Deadly Parasite (2) Malaria on the rise since 1970 Drug resistant Plasmodium Insecticide resistant mosquitoes Clearing of tropical forests AIDS patients particularly vulnerable Prevention of spread and current research DDT effective against mosquitoes but banned in U.S. DDT (dichlorodiphenyltrichloroethane) is a colorless, crystalline, tasteless and almost odorless organochloride known for its insecticidal properties.
Global Outlook: Distribution of Malaria Fig. 17-6, p. 444
Science Focus: Genetic Resistance to Antibiotics Is Increasing (1) Bacteria: rapid reproduction, easily spread Overuse of antibiotics Overuse of pesticides Widespread use of pesticides or antibiotics eliminates the weaker individuals in a rapidly reproducing population. This causes an increase in the frequency of individuals in the population who have genetic resistance to pesticides or antibiotics because they are the ones left to rapidly reproduce.
Case Study: The Growing Global Threat from Tuberculosis One in ten will become sick with TB 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
Lung Tissue Destroyed by Tuberculosis Fig. 17-5, p. 440
Science Focus (p. 442) Ecological Medicine: How Humans Get Infectious Diseases from Animals Human practices that encourage the spread of diseases from animals to humans Emerging infections HIV Ebola virus Avian flu Hepatitis B Lyme virus
A Boy in Brazil’s Amazon Sleeps Under an Insecticide-Treated Mosquito Net Fig. 17-7, p. 445 This boy, who lives in Brazil’s Amazon Basin, is sleeping under an insecticide-treated mosquito net to reduce his risk of being bitten by malaria-carrying mosquitoes. Such nets cost about $5 each an can be donated through groups such as g.
We Can Reduce the Incidence of Infectious Diseases Good news Vaccinations on the rise Oral rehydration therapy Bad news More money needed for medical research in developing countries
Solutions: Infectious Diseases Fig. 17-8, p. 445
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.
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
Top 5 Toxic Substances—Human and Environmental Health Arsenic Lead Mercury Vinyl chloride Used to make PVC plastics Polychlorinated biphenyls PCBs
Case Study: PCBs Are Everywhere— A Legacy from the Past Polychlorinated Biphenyl (PCB)-- Class of chlorine-containing compounds Very stable Nonflammable Break down slowly in the environment Travel long distances in the air Fat soluble Bioaccumulation Biomagnification Food chains and webs Banned, but found everywhere
Case Study: PCBs Are Everywhere— A Legacy from the Past PCBs belong to a broad family of man-made organic chemicals known as chlorinated hydrocarbons. PCBs were domestically manufactured from 1929 until their manufacture was banned in PCBs were used in hundreds of industrial and commercial applications including electrical, heat transfer, and hydraulic equipment; as plasticizers in paints, plastics, and rubber products; in pigments, dyes, and carbonless copy paper; and many other industrial applications.
PCBs Once in the environment, PCBs do not readily break down and therefore may remain for long periods of time cycling between air, water, and soil. PCBs can be carried long distances and have been found in snow and sea water in areas far away from where they were released into the environment. As a consequence, PCBs are found all over the world. PCBs can accumulate in the leaves and above-ground parts of plants and food crops. They are also taken up into the bodies of small organisms and fish. As a result, people who ingest fish may be exposed to PCBs that have bioaccumulated in the fish they are ingesting. PCBs have been demonstrated to cause cancer, as well as a variety of other adverse health effects on the immune system, reproductive system, nervous system, and endocrine system.
Potential Pathways on Which Toxic Chemicals Move Through the Environment Fig. 17-9, p. 447 PCBs and other persistent toxic chemicals can move through th living and nonliving environment on a number of pathways.
Bioaccumulation and Biomagnification Bioaccumulation: Organisms that consume toxic materials that do not break down will eventually excrete or store these chemicals in their fatty tissues (fat soluble) over time; organisms can have a build up of toxins/chemicals. Biomagnification: The increased concentration of toxins in the tissues of organisms that are in higher levels of the food web/chain. Example: DDT (dichlorodiphenyltrichloroethane) is a colorless, crystalline, tasteless and almost odorless organochloride known for its insecticidal properties. Found in tissues of different organisms within an aquatic ecosystem: DDT in a water system ppm Water is consumed by algae, and the toxin is concentrated to 0.04 ppm. Algae are consumed by primary consumers—shrimp—and the toxin is concentrated to 0.16 ppm. Shrimp are consumed by Secondary Consumers, eels, and the toxin is concentrated to 0.28 ppm. Eels are consumed by the Tertiary Consumers, the ring-billed gull, and the toxin is concentrated to 75.5 ppm.
Some Chemicals May Affect Our Immune and Nervous Systems Some natural and synthetic chemicals in the environment can weaken and harm: Immune system Nervous system Neurotoxins: PCBs, arsenic, lead, some pesticides Endocrine system Hormones
Some Chemicals Affect the Human Endocrine System Glands that release hormones that regulate bodily systems and control sexual reproduction, growth, development, learning, behavior Hormonally active agents have similar shapes and bind to hormone receptors “Gender benders” Thyroid disruptors BPA? Phthalates in plastics
Science Focus: Mercury’s Toxic Effects (1) 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? 1.Inhalation: vaporized Hg or particulates 2.Eating fish with high levels of methylmercury Under certain conditions in aquatic environments, bacteria can convert inorganic mercury compounds to highly toxic methylmercury, which can be biomagnified in food chains/ webs. 3. Eating high-fructose corn syrup??
Science Focus: Mercury’s Toxic Effects (2) Effects of Hg on humans Damage nervous system, kidneys, lungs Harm fetuses and cause birth defects Who is most at risk? Pregnant women 75% of exposure comes from eating fish
Solutions: Mercury Pollution Fig , p. 449
Superfund Act Comprehensive Environmental Response, Compensation & Liability Act (CERCLA): Otherwise known as the Superfund Act- calls for a rapid cleanup of abandoned dumpsites containing toxic waste.
Video: Hazardous Chemicals in Urban Environments Habitable Planet
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.
Many Factors Determine the Harmful Health Effects of a Chemical (1) Toxicology Toxicity dependent on Dose Age Genetic makeup Multiple chemical sensitivity (MCS) Solubility Persistence Biomagnification
Many Factors Determine the Harmful Health Effects of a Chemical (2) Response Acute effect: immediate or rapid Chronic effect: permanent or long-lasting
Science: Estimating Human Exposure to Chemicals and Measuring Their Effects Fig , p. 452
Case Study: Protecting Children from Toxic Chemicals Analysis of umbilical cord blood: significance Infants and children more susceptible 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 Fetal exposure may increase risk of autism, asthma, learning disorders
Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity (1) Mice and rats Systems are similar to humans Small, and reproduce rapidly Is extrapolation to humans valid? Dose-response curve: median lethal dose (LD50) Nonthreshold dose-response model Threshold dose-response model
Scientists Use Live Lab Animals and Nonanimal Tests to Estimate Toxicity (2) More humane methods using animals Replace animals with other models Computer simulations Tissue culture and individual animal cells Chicken egg membranes What are the effects of mixtures of potentially toxic chemicals?
Hypothetical Dose-Response Curve Showing Determination of the LD50 (median lethal dose) Fig , p. 453 * LD50 is the dose required to be lethal for 50% of the test population.
Toxicity Ratings and Average Lethal Doses for Humans Table 17-1, p. 453
Science: Two Types of Dose-Response Curves Fig , p. 454
There Are Other Ways to Estimate the Harmful Effects of Chemicals Case reports and epidemiological studies Limitations of epidemiological studies Too few people tested Length of time Can you link the result with the chemical? Cannot be used for new hazards
Are Trace Levels of Toxic Chemicals Harmful? Insufficient data for most chemicals We are all exposed to toxic chemicals Are the dangers increasing or are the tests just more sensitive?
Some Potentially Harmful Chemicals Found in Most Homes Fig , p. 455
Why Do We Know So Little about the Harmful Effects of Chemicals? Severe limitations estimating toxicity levels and risks Only 2% of 100,000 chemicals have been adequately tested 99.5% of chemicals used in the United States are not supervised by government
Pollution Prevention and the Precautionary Principle Those introducing a new chemical or new technology would have to follow new strategies A new product is considered harmful until it can be proved to be safe Existing chemicals and technologies that appear to cause significant harm must be removed 2000: global treaty to ban or phase out the dirty dozen persistent organic pollutants (POPs) 2007 REACH program in the European Union
Individuals Matter: Ray Turner and His Refrigerator 1974: Ozone layer being depleted by chlorofluorocarbons (CFCs) 1992: International agreement to phase out CFCs and other ozone-destroying chemicals Ray Turner: citrus-based solvents to clean circuit boards
17-5 How Do We Perceive Risks and How Can We Avoid the Worst of Them? Concept 17-5 We can reduce the major risks we face by becoming informed, thinking critically about risks, and making careful choices.
The Greatest Health Risks Come from Poverty, Gender, and Lifestyle Choices Risk analysis Risk assessment Risk management Risk communication Greatest health risks Poverty Gender Lifestyle choices
Global Outlook: Number of Deaths per Year in the World from Various Causes Fig , p. 458
Comparison of Risks People Face in Terms of Shorter Average Life Span Fig , p. 459
Case Study: Death from Smoking (1) Most preventable major cause of suffering and premature death Premature death of 5.4 million per year globally and 442,000 in the United States Could be linked to increased dementia and Alzheimer’s disease Nicotine: additive Effects of passive smoking (secondhand smoke)
Case Study: Death from Smoking (2) How to reduce smoking Taxes Classify and regulate nicotine Bans on smoking in public places Education
Normal Lung and Emphysema Lung Fig , p. 459
Annual Deaths in the U.S. from Tobacco Use and Other Causes Fig , p. 460
Most People Do a Poor Job of Evaluating Risks 1.Fear 2.Degree of control 3.Whether a risk is catastrophic or chronic 4.Optimism bias 5.Want instant gratification without thinking of future harm
Several Principles Can Help Us to Evaluate and Reduce Risk 1.Compare risks 2.Determine how much you are willing to accept 3.Determine the actual risk involved 4.Concentrate on evaluating and carefully making important lifestyle choices
Three Big Ideas 1.We face significant hazards from infectious diseases, malaria, and tuberculosis, and from exposure to chemicals that can cause cancers and birth defects, and disrupt the human immune, nervous, and endocrine systems. 2.Because of the difficulty in evaluating the harm caused by exposure to chemicals, many health scientists call for much greater emphasis on pollution prevention.
Three Big Ideas 3.Becoming informed, thinking critically about risks, and making careful choices can reduce the major risks we face.