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Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2008.

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Presentation on theme: "Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2008."— Presentation transcript:

1 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Slides prepared by Jay Withgott and Heidi Marcum Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Ch 14 Environmental Health and Toxicology Part 2: Environmental Issues and the Search for Solutions

2 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings This lecture will help you understand: Environmental health hazards Toxicants in the environment Hazards and their effects Philosophical approaches to risk Policy and regulation in the U.S. and world Alligator hatchling from Lake Apopka Florida (Start, 11/04/2008)

3 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings This lecture will help you understand: Environmental health hazards Toxicants in the environment Hazards and their effects Risk assessment and risk management Philosophical approaches to risk Policy and regulation in the U.S. and world Alligator hatchling from Lake Apopka Florida (Start, 11/04/2008)

4 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Central Case: Lake Apopka alligators, 1985 Alligators in Lake Apopka, Florida, had reproductive problems: unhealthy eggs, abnormal sex hormone level The lake had high levels of agricultural runoff Chemical contaminants were disrupting the endocrine systems of alligators during egg development - Pesticides, fertilizer(Nitrate) runoff to the lake (Guillette, 2003).

5 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings There are many types of environmental hazards (Four Types) Environmental health : assesses environmental factors that influence human health and quality of life -Natural and human-caused factors are both considered 1. Physical hazards : occur naturally in our environment -Earthquakes, volcanoes, fires, floods, droughts we can prepare for some of them -We increase our vulnerability by deforesting slopes (landslides), channelizing rivers (flooding), etc. -We can reduce risk by better environmental choices

6 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Chemical & biological environmental hazards 2. Chemical: synthetic chemicals such as pesticides, disinfectants, pharmaceuticals -Harmful natural chemicals also exist Urushiol (an oil in poison ivy, etc.) 3. Biological : result from ecological interactions -Viruses, bacteria, and other pathogens -Infectious (communicable, or transmissible) disease other species parasitize humans, fulfilling their ecological roles -We can’t avoid risk, but we can reduce the likelihood of infection

7 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Cultural environmental hazards 4. Cultural: result from the place we live, our socioeconomic status, our occupation, our behavioral choices -Smoking, drug use, diet and nutrition, crime, mode of transportation

8 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Four types of environmental hazards

9 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Disease is a major focus of environmental health Despite our technology, disease kills most of us Disease has a genetic and environmental basis -Cancer, heart disease, respiratory disorders -Poverty and poor hygiene can foster illnesses

10 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Infectious diseases kill millions Infectious diseases kill 15 million people per year -Half of all deaths in developing countries -Developed countries have better hygiene, access to medicine, and money Vector : an organism that transfers pathogens to a host Mosquito, Malaria Plasmodium apicomplexan Lice, Typhus, Rickettsia prowazekii Ticks, Lime Disease, Borrelia

11 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Many diseases are increasing Tuberculosis (TB) - mycobacteria Acquired immunodeficiency syndrome (AIDS), & the West Nile virus - virus (ss-RNA) Our mobility spreads diseases - Globalization Diseases are evolving resistance to antibiotics To predict and prevent diseases, experts deal with complicated interrelationships

12 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: bacteria, viruses, viroids, prions Bacteria: Mycobacteria(Tuberculosis) Single Stranded-RNA: Tobacco Mosaic Virus Human ImmunoDeficiency Virus (HIV ): Acquired ImmunoDeficiency Syndrome (AIDS) West Nile Virus : Meningitis, Encephalitis Viroids (circilar RNA): Cadang cadang ( coconut palm disease) Prions (Proteins): mad cow disease, kuru - long incubation period Diseases are evolving resistance to antibiotics

13 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: bacteria, viruses, viroids, prions Bacteria: Mycobacteria(Tuberculosis) Virus: Single Stranded-RNA: Tobacco Mosaic Virus Human ImmunoDeficiency Virus (HIV ): Acquired ImmunoDeficiency Syndrome (AIDS) West Nile Virus : Meningitis, Encephalitis Viroids (circilar RNA): Cadang cadang ( coconut palm disease) Prion (Protein + Infection): Mis-folded Protein, neuro-degerative Mad Cow Disease (bovine spongiform encephalopathy, BSE), 1986, UK, ~ 4.5 M cows slaughtered/burned Kuru (Fore Tribe in Papua) Diseases are evolving resistance to antibiotics

14 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Many old diseases are gone (w/ antibiotics), but new ones emerging Pathogens: Bacteria, Viruses, Viroids, Prions Bacteria: Mycobacteria(Tuberculosis) Virus: RNS/DNA + Protein Coat (+ Lipid Envelope) Tobacco Mosaic Virus: Single Stranded-RNA: Human ImmunoDeficiency Virus (HIV ): Acquired ImmunoDeficiency Syndrome (AIDS) West Nile Virus : Meningitis, Encephalitis Viroids (circilar RNA): Plant pathogen Cadang cadang ( coconut palm disease) Prion (Protein + Infection): Mis-folded Protein, neuro-degerative Bovine Spongiform Encephalopathy(BSE, Mad Cow Disease), 1986, UK, ~ 4.5 M cows slaughtered/burned Creutzfeldt–Jakob Disease (CJD), Kuru (Fore Tribe in Papua) claimed ~200 people in late 2000s in UK Diseases are evolving resistance to antibiotics

15 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings AIDS Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS or Aids) is a set of symptoms and infections resulting from the damage to the human immune system caused by the human immunodeficiency virus (HIV). [1] This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk. [2][3] This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, or breastfeeding, or other exposure to one of the above bodily fluids.set of symptoms and infectionsimmune systemhuman immunodeficiency virus [1] opportunistic infectionstumorstransmittedmucous membranebodily fluidbloodsemen vaginal fluidpreseminal fluidbreast milk [2][3]anal vaginaloralsexblood transfusionhypodermic needlespregnancychildbirthbreastfeeding AIDS is now a pandemic. [4] In 2007, an estimated 33.2 million people lived with the disease worldwide, and it killed an estimated 2.1 million people, including 330,000 children. [5] Over three-quarters of these deaths occurred in sub-Saharan Africa, [5] retarding economic growth and destroying human capital. [6] Most researchers believe that HIV originated in sub-Saharan Africa during the twentieth century. [7] AIDS was first recognized by the U.S. Centers for Disease Control and Prevention in 1981 and its cause, HIV, identified by American and French scientists in the early 1980s. [8]pandemic [4] [5] economic growthhuman capital [6]sub-Saharan Africa [7]Centers for Disease Control and Prevention [8] Although treatments for AIDS and HIV can slow the course of the disease, there is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries. [9] Due to the difficulty in treating HIV infection, preventing infection is a key aim in controlling the AIDS epidemic, with health organizations promoting safe sex and needle-exchange programmes in attempts to slow the spread of the virus.Antiretroviralmortalitymedication [9] safe sexneedle-exchange programmes

16 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Immune System An immune system is a collection of mechanisms within an organism that protects against disease by identifying and killing pathogens and tumor cells. It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly. Detection is complicated as pathogens can evolve rapidly, producing adaptations that avoid the immune system and allow the pathogens to successfully infect their hosts.organism diseasepathogenstumorvirusesparasitic wormscellstissuesevolveadaptationshosts To survive this challenge, multiple mechanisms evolved that recognize and neutralize pathogens. Even simple unicellular organisms such as bacteria possess enzyme systems that protect against viral infections. Other basic immune mechanisms evolved in ancient eukaryotes and remain in their modern descendants, such as plants, fish, reptiles, and insects. These mechanisms include antimicrobial peptides called defensins, phagocytosis, and the complement system. Vertebrates such as humans have even more sophisticated defense mechanisms. [1] The immune systems of vertebrates consist of many types of proteins, cells, organs, and tissues, which interact in an elaborate and dynamic network. As part of this more complex immune response, the human immune system adapts over time to recognise specific pathogens more efficiently. This adaptation process is referred to as "adaptive immunity" or "acquired immunity" and creates immunological memory. Immunological memory created from a primary response to a specific pathogen, provides an enhanced response to secondary encounters with that same, specific pathogen. This process of acquired immunity is the basis of vaccination.evolvedunicellularbacteriaenzymeviral eukaryotesplantsfishreptilesinsectsantimicrobial peptidesdefensinsphagocytosis complement systemVertebrates [1]proteins organsacquired immunityimmunological memoryvaccination Disorders in the immune system can result in disease. Immunodeficiency diseases occur when the immune system is less active than normal, resulting in recurring and life-threatening infections. Immunodeficiency can either be the result of a genetic disease, such as severe combined immunodeficiency, or be produced by pharmaceuticals or an infection, such as the acquired immune deficiency syndrome (AIDS) that is caused by the retrovirus HIV. In contrast, autoimmune diseases result from a hyperactive immune system attacking normal tissues as if they were foreign organisms. Common autoimmune diseases include rheumatoid arthritis, diabetes mellitus type 1 and lupus erythematosus. Immunology covers the study of all aspects of the immune system which has significant relevance to human health and diseases. Further investigation in this field is expected to play a serious role in promotion of health and treatment of diseases.Immunodeficiencygenetic diseasesevere combined immunodeficiency acquired immune deficiency syndromeretrovirusHIVautoimmunerheumatoid arthritisdiabetes mellitus type 1lupus erythematosusImmunology

17 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Environmental health hazards exist indoors Radon: Can build up in basements 86 Rn-222 → 84 Pb α-ray ( 2 4 He) a highly toxic, radioactive gas colorless & undetectable. Carbon Monoxide (CO): Lead (Pb 2+ ) poisoning: from lead pipes by mimicking Ca 2+, Fe 2+, & Zn 2+ ions Damages organs (Brain, Liver, Kidney, etc); causes learning problems, behavior abnormalities, & death Asbestos: Mg 3 [Si 2 O 5 ](OH) 4 (white) insulates heats, muffles sounds, & resists fire (retardant): - does not degrade Asbestosis: scarred lungs may cease to function, & Lung Cancer Removing Asbestos

18 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Natural Disintegrations of Radiosotpopes The major source of geothermal energy (γ-ray) Occurs in Earth Crust, Mantle, &Core 40 K → 40 Ar(g) (1.28 Gy) Source of atmospheric Ar 238 U → → → 226 Ra → 222 Rn(g) → → → 206 Pb (4.47G y) 235 U → → → 223 Ra → 219 Rn(g) → → → 207 Pb (0.704 Gy) 232 Th → → → 224 Ra → 220 Rn(g) → → → 208 Pb (14 Gy) Artificial Disintegrations (“forced”) -Atomic Bomb & Nuclear Power Plant : 235 U + n → 91 Kr Kr +3n Add(9/12/2013) 7th Mtg starts (9/9/08)

19 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings A recently recognized hazard Polybrominated diphenyl ethers (PBDEs): has fire-retardant properties -Used in computers, televisions, plastics, and furniture -Persist and accumulate in living tissue -Endocrine disruptors: compounds that mimic hormones and interfere with the functioning of animals’ endocrine (hormone) systems -Affect brain and nervous system development, and may cause cancer

20 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxicology is the study of poisonous substances Toxicology: the study of the effects of poisonous substances on humans and other organisms Toxicity : the degree of harm a toxicant can cause -“The dose makes the poison” : Paracelsus( ) toxicity depends on the combined effect of the chemical and its quantity -Analogous to pathogenicity or virulence : the degree of harm of biological hazards that spread disease Toxicant : any toxic agent

21 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxicology is the study of poisonous substances Toxicology: the study of the effects of poisonous substances on humans and other organisms Toxicity : the degree of harm a toxicant can cause -“The dose makes the poison” : toxicity depends on the combined effect of the chemical and its quantity Toxicant : any toxic agent

22 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Environmental toxicology Deals with toxic substances that come from or are discharged into the environment Studies the health effects on humans, other animals, and ecosystems -Focus mainly on humans, using other animals as test subjects -Can serve as indicators of health threats Don’t forget, chemicals have given us our high standard of living

23 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxic agents in the environment The environment contains countless natural chemicals that may pose health risks But, synthetic chemicals are also in our environment -Every human carries traces of industrial chemicals 80% of U.S. streams contain at least trace amounts of 83 wastewater contaminants

24 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Very few chemicals have been thoroughly tested 10 M chemical substances (Natural & Artificial) Known Table ,000 chemicals (1 % of the 10 M) are on the market today -72,000 Industrial - 8,700 Food additives - 2,000 New chemicals introduced per year Pesticides - 7,500 Cosmetic ingredients - 3,300 Pharmaceuticals We don’t know the effects, if any, they have

25 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Silent Spring began public debate over chemicals Dichloro-Diphenyl-Trichloroethane (DDT): a neurotoxin inhibit normal function of neuron → spasm, death Rachel Carson published Silent Spring in Brought together studies to show DDT risks to people, wildlife, and ecosystems (banned in US in 1972) -In the 1960s, pesticides were mostly untested and were sprayed over public areas, assuming they would do no harm The book generated significant social change: (cf. p 68) triggering enactment of Many Environmental Protection Laws since 1963 (→ saved bald eagles)

26 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Types of toxicants: Carcinogens: cause cancer Mutagens: cause DNA mutations -Can lead to severe problems, including cancer Teratogens: cause birth defects Allergens: induce unnecessary immune responses Neurotoxins: assault the nervous system Endocrine disruptors: interfere with the normal hormonal function Thalidomide, sedative,sedative late 50s, 60s

27 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Endocrine disruption may be widespread Theo Colburn, et al. (World Wildlife Fund) wrote Our Stolen Future in Synthetic industrial chemicals may be altering the hormones of animals -This book integrated scientific work from various fields -Shocked many readers and brought criticism from the chemical industry

28 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Evidence for hormone disruption Frogs also have gonadal abnormalities -Male frogs became feminized from atrazine (herbicide) concentrations well below EPA → inhibit photosynthesis PCB (PolyChlorinated Biphenyls): Coolants, Insulating fluids in transformer, additives in plastics contaminated human babies were born weighing less, with smaller heads. → Banned in 1970 Research Scientist (Academia) vs. Industry-backed Scientist

29 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Male sperm counts are dropping Drop in men’s sperm counts may be caused by endocrine disruptors -The number and motility of sperm has dropped 50% since 1938, in more industrialized country in particular Testicular cancer, undescended testicles, and genital birth defects are also increasing

30 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Endocrine disruption research is controversial Research results are uncertain, which is inherent in any young field Negative findings pose economic threats to chemical manufacturers -Banning a top-selling chemical could cost a company millions of dollars -Bisphenol-A, found in plastics, can cause birth defects, but the plastics industry protests that the chemical is safe epoxy resins & other plastics (bottles, CD/DVD, etc.) Studies reporting harm are publicly funded, but those reporting no harm are industry funded

31 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxins may concentrate in water Runoff carries toxins from large land areas to small volumes of surface water Chemicals can leach into the soil Chemicals enter organisms through drinking or absorption -Aquatic organisms are effective pollution indicators → Oyster

32 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Routes of chemical transport

33 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Airborne toxicants travel widely, globally Chemicals can travel by air, their effects can occur far from the site of chemical use Pesticide drift = airborne transport of pesticides Synthetic chemical contaminants are found globally -They appear in arctic polar bears, Antarctic penguins, and people living in Greenland

34 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Some toxicants persist for a long time Toxins can degrade quickly and become harmless -Or, they may remain unaltered and persist for decades -Rates of degradation depends on temperature, moisture, and sun exposure Persistent chemicals have the greatest potential for harm Breakdown products = toxicants degrade into simpler products -May be more or less harmful than the original substance -DDT degrades into DDE, which is also highly persistent

35 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Toxicants can accumulate and biomagnify DDT (from Zooplankton to Fish to Falcon) Some toxicants can be excreted or metabolized However, many Fat-soluble toxicants are stored in fatty tissues Bioaccumulation = toxicants build up in animal tissues Biomagnification = toxicants concentrate in top predators -Near extinction of peregrine falcons and brown pelicans Note: ppm = 10,000 x %

36 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Not all toxicants are synthetic Chemical toxicants also exist naturally and in our food -Don’t assume natural chemicals are all healthy and synthetic ones are all harmful -Snake venom (mixture of various proteins) urushiol(poison ivy), tetrodotoxin (puff fish) Some scientists feel that natural toxicants dwarf our intake of synthetic chemicals -Natural defenses against toxins are effective against synthetic ones, too -Critics say natural toxins are more readily metabolized and excreted, and synthetic chemicals persist and accumulate

37 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Wildlife studies Museum collections provide data from times before synthetic chemicals were used Measurements from animals in the wild can be compared to controlled experiments in the lab Scientists can first measure effects in the lab, then look for correlations in the wild Conspicuous mortality events can trigger research -Many sea otters died and washed ashore -Research showed they died from parasites carried in sewage runoff containing cat litter

38 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Human studies Case histories = studying sickened individuals directly -Autopsies -Don’t tell about future risks Epidemiology = large-scale comparisons between groups of people -Studies between exposed and unexposed people last for years -Yield accurate predictions about risk Animals are used as test subjects -Some people object to animal research -New techniques (human cell cultures, bacteria, etc.) may replace some live-animal testing

39 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Dose-response analysis Dose-response analysis: measuring how much effect a toxicant produces at different doses -Animal testing -Dose: the amount of toxicant the test animal receives -Response: the type or magnitude of negative effects of the animal -Dose-response curve: the plot of dose given against response

40 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Dose response curves LD 50 : the amount of toxicant required to kill 50% of the subjects The smaller this value, the more toxic Threshold: the dose level where certain responses occur Scientists extrapolate downward from animal studies to estimate the effect on humans -Regulatory agencies set allowable limits well below toxicity levels in lab studies

41 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings LD 50 for some chemicals (mostly, for rats, oral route) mg/kg Table Sugar 29,700 Vitamin C 11,900 EtOH 7,060 NaCl 3,000 FeSO 4 1,500 Caffeine 190 NaNO Heroin 150 mg/kg Pb 20 Cocaine 17.5 NaCN 6.4 Nicotine 1 Tetrodotoxin 0.1 Snake Venom ~0.025 Dioxin Polonium

42 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Individuals vary in their responses to hazards Different people respond differently to hazards -Affected by genetics, surroundings, etc. -People in poor health are more sensitive -Sensitivity also varies with sex, age, and weight -Fetuses, infants, and young children are more sensitive Standards for responses are set by the Environmental Protection Agency (EPA) -Often, standards are not low enough to protect babies

43 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The type of exposure affects the response Acute exposure: high exposure for short periods of time to a hazard -Easy to recognize -Stem from discrete events: ingestion, oil spills, nuclear accident Chronic exposure: low exposure for long periods of time to a hazard -Hard to detect and diagnose -Affects organs gradually: lung cancer, liver damage -Cause and effect may not be easily apparent

44 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Mixes may be more than the sum of their parts We can’t determine the impact of mixed hazards -They may act in ways that cannot be predicted from the effects of each in isolation Synergistic effects = interactive impacts that are more than or different from the simple sum of their constituent effects -Mixed toxicants can sum, cancel out, or multiply each other’s effects -New impacts may arise from mixing toxicants

45 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Risk assessment Risk: the probability that some harmful outcome will result from a given action -Exposure to environmental health threats doesn’t automatically produce an effect -Rather, it causes some probability (likelihood) of harm Probability entails -Identity and strength of threat -Chance & frequency that an organism will encounter it -Amount of exposure to the threat -An organism’s sensitivity to the threat

46 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Risk assessment Risk: the probability that some harmful outcome will result from a given action -Exposure to environmental health threats doesn’t automatically produce an effect -Rather, it causes some probability (likelihood) of harm Probability involves -Identity and strength of threat -Chance/frequency that an organism will encounter it -Amount of exposure to the threat -An organism’s sensitivity to the threat

47 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Perception of Risk vs. Reality of Risk Everything we do involves some risk We try to minimize risk, but we often misperceive it - Flying poses 50 x less risk than Driving We feel more at risk when we cannot control a situation -We fear nuclear power and toxic waste, but not smoking or overeating

48 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Analyzing risk quantitatively Risk assessment: the quantitative measurement of risk and the comparison of risks involved in different activities or substances -It is a way of identifying and outlining problems Several steps: -Scientific study of toxicity -Assessing an individual or population’s likely extent of exposure to the substance, including frequency, concentrations, and length of exposure Studies are often performed by industry-associated scientists, which may undermine the study’s objectivity

49 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Risk management Combines decisions and strategies to minimize risk Scientific assessments are considered with economic, social, and political needs and values Developed nations have federal agencies to manage risk -The U.S. has the Centers for Disease Control (CDC), the EPA, and the Food and Drug Administration (FDA) Comparing costs and benefits is hard -Benefits are economic and easy to calculate -Health risks (costs) are hard-to-measure probabilities of a few people being affected

50 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The process of risk management

51 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings One approach to determining safety Innocent until proven guilty approach: product manufacturers must prove a product is safe -Benefits: now slowing down technological innovation and economic advancement -Disadvantage: putting into wide use some substances that may later on turn out to be dangerous

52 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Another approach to determining safety Precautionary principle approach: (~ Guilty until proven innocent approach) the government, scientists, and the public are required to prove a product is dangerous -Assume substances are harmful until they are proven harmless -Identifies troublesome toxicants before they are released -But, this may impede the pace of technology and economic advance

53 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Two approaches to determining safety Innocent until proven guilty approach: Guilty until proven innocent approach: (Precautionary principle approach) the government, scientists, and the public are required to prove a product is dangerous -Assume substances are harmful until they are proven harmless -Identifies troublesome toxicants before they are released -But, this may impede the pace of technology and economic advance

54 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Two approaches for determining safety

55 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Philosophy affects policy Different nations use different policies; most use a mix between the “innocent until proven guilty” principle and the precautionary principle -Europe is shifting more towards the precautionary principle -Industries like the “innocent until proven guilty” approach because it allows them to produce more and make more money

56 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The EPA regulates many substances Federal agencies apportion responsibility for tracking and regulating synthetic chemicals -FDA: food, food additives, cosmetics, drugs, and medical devices -EPA: pesticides -Occupational Safety and Health Administration (OSHA): workplace hazards Many public health and environmental advocates fear it isn’t enough -Many synthetic chemicals are not actually tested -Only 10% have been tested for toxicity -Fewer than 1% are government regulated

57 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings International regulation Nations address chemical pollution with international treaties Stockholm Convention on Persistent Organic Pollutants (POPs) was ratified by 140 nations in Ends the release of the 12 most dangerous POPs “ The Dirty Dozen” (Table 14.3, p407) 8 pesticides and others EU’s Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) Program -Aims to evaluate and restrict dangerous chemicals while giving industries a streamlined regulatory system -It will cost the chemical industry 2.8 – 5.2 billion euros (U.S. $3.8 – 7.0 billion), but will save more than 10 times that in health benefits (End, 11/04/2008)

58 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Conclusion International agreements represent a hopeful sign that governments are working to protect society, wildlife, and ecosystems from toxic chemicals and environmental hazards Once all the scientific results are in, society’s philosophical approach to risk management will determine what policies are enacted A safe and happy future depends on knowing the risks that some hazards pose and on replacing those substances with safer ones

59 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Which of the following is a biological hazard? a)Earthquake b)Smoking c)Virus d)A pesticide e)All are biological hazards

60 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review A “vector” is defined as … a)A highly toxic, radioactive compound b)An organism that transfers pathogens to a host c)A compound with fire-retardant properties d)A compound that mimics natural substances

61 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Toxicity is … a)The study of the effects of poisonous substances b)Any toxic agent c)Any substance that causes environmental degradation d)The degree of harm a substance can cause

62 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review A “teratogen” causes…? a)Cancer b)Mutations c)Birth defects d)Problems in the hormonal system

63 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review Why is research into endocrine disrupters controversial? a)Negative findings threaten the industry’s economics b)Research is still only beginning c)Much research is funded by industry d)All of these are reasons why research is controversial

64 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Review A human-based study that compares a group of smokers to non-smokers to determine the effects of smoking is … a)An epidemiological study b)A case study c)Not likely to be funded d)Not going to tell about future risks

65 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Interpreting Graphs and Data Our perception, and the reality, of risk often do not match. Given this graph (reality), and your knowledge of sources of anxiety (perception), which statement is correct? a)Smoking is very dangerous and we are very anxious about it b)Smoking is not dangerous, but we are very anxious about it c)Airplane accidents are dangerous, and we are very anxious about it d)Airplane accidents are not dangerous, but we are very anxious about it

66 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Our perception, and the reality, of risk often do not match. Given this graph (reality), and your knowledge of sources of anxiety (perception), which statement is correct? a)Smoking is very dangerous and we are very anxious about it b)Smoking is not dangerous, but we are very anxious about it c)Airplane accidents are dangerous, and we are very anxious about it d)Airplane accidents are not dangerous, but we are very anxious about it

67 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Interpreting Graphs and Data If the “low” dose = 5 units of a chemical, the “medium” dose = 10 units, and the “high” dose = 15 units, how much of the chemical is required to kill 50% of the study population? From The Science behind the Stories a)About 5 units b)About 10 units c)About 15 units d)You can’t tell from the graph

68 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Viewpoints Is it unethical for a country that has banned a chemical to manufacture and export it to other countries? a)Yes; if we won’t have it in the U.S., we shouldn’t make it b)Yes, but the money we get from selling it will help our economy c)No; let people decide what they want to do d)No; in fact, chemicals should not be banned in the U.S. either

69 Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings QUESTION: Viewpoints Should the government follow the precautionary principle and force industries to prove their products are safe? a)Absolutely; it is up to industry to prove its chemicals are safe b)Maybe, if it is not too expensive c)No; let the government and scientists prove a chemical is dangerous before it is taken off the market d)No, as long as the product makes money and jobs for the industry, it should be allowed


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