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Human Health and Environmental Risks. Four categories of human health risks Physical (floods, blizzards, landslides, radon, UV exposure) Biological (viruses,

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Presentation on theme: "Human Health and Environmental Risks. Four categories of human health risks Physical (floods, blizzards, landslides, radon, UV exposure) Biological (viruses,"— Presentation transcript:

1 Human Health and Environmental Risks

2 Four categories of human health risks Physical (floods, blizzards, landslides, radon, UV exposure) Biological (viruses, bacterial infections) Chemical (disinfectants, pesticides) Cultural/Lifestyle (drinking, smoking, bad diet, crime in neighborhood)

3 Biological Risks Infectious diseases- those caused by infectious agents, known as pathogens. Example: pneumonia and Flu Also referred to as: transmissible, contagious or communicable diseases. Where you live and your level of poverty may increase the probability of contracting some infectious diseases.


5 Biological Risks  Epidemic – An outbreak of an infectious disease that is limited to one area or region.  Pandemic – If outbreak of a disease spreads globally.

6 Biological Risks Chronic disease- slowly impairs the functioning of a person’s body. Acute diseases- rapidly impair the functioning of a person’s body.


8 Historical Diseases Plague Malaria Tuberculosis Cholera Dysentery

9 Emergent Diseases HIV/AIDS Ebola Mad Cow Disease Bird Flu West Nile Virus SARS Antibiotic resistant TB

10 Agencies CDC – Center for Disease Control and Prevention (United States) WHO – World Health Organization (global)

11 Solutions for Reducing Infectious Disease  Improving drinking water conditions in developing countries  Decreasing malnutrition to improve immune system  Implementing global education programs to prevent HIV/AIDS  Increasing availability to vaccines/antibiotics  Reducing unnecessary use of antibiotics in humans and livestock

12 Chemical Risks Toxicology – Study of the detrimental effects of chemicals on both humans and wildlife Key characteristics that cause a chemical to be toxic include:  Persistence – not easily degraded/broken down  Solubility – fat soluble chemicals will accumulate in body tissues, water soluble chemicals will be dissolved easily in bodies of water  Biomagnification – Increased concentration of chemical through the food chain.

13 Bioaccumulation bioaccumulation- an increased concentration of a chemical within an organism over time

14 Biomagnification Biomagnification- the increase in a chemical concentration in animal tissues as the chemical moves up the food chain.

15 Dose-Response Studies LD50- lethal dose that kills 50% of the individuals ED50- effective dose that causes 50% of the animals to display the harmful but nonlethal effect (referred to as sublethal effects) Because of the short duration of these experiments, referred to as acute studies

16 Synergistic interactions- when two risks come together and cause more harm that one would. For example, the health impact of a carcinogen such as asbestos can be much higher if an individual also smokes tobacco.


18 Dose-response curve LD 50 = dose lethal to 50% of test animals Threshold = dose at which response begins

19 Do The Math Based on a LD50 pesticide study on a rat, what amount of the pesticide would be considered safe for a mammal? LD50 ÷ 10 (mammal) LD 50 = 2mg/kg of mass ÷ 10 = 0.2 mg/kg of mass LD50 ÷ 1000 (humans) LD 50 = 2mg/kg of mass ÷1000 = mg/kg of mass

20 Problems with Toxicity Testing There are many issues in accurately assessing toxicity of chemicals….  Genetic Variability – individuals can exhibit different response to a given level or type of chemical  Test only one response to one chemical at a time, difficult to determine synergistic effects  Type of exposure may effect response (acute versus chronic)  Regulating agencies may rely on Industry sponsored research

21 Chemical Risks Neurotoxins- chemicals that disrupt the nervous system Carcinogens- chemicals that cause cancer Teratogens- chemicals that interfere with the normal development of embryos or fetuses Allergens- chemicals that cause allergic reactions Endocrine disruptors- chemicals that interfere with the normal functioning of hormones in an animal’s body

22 Routes of Exposure

23 Many health hazards exist indoors Substances in plastics and consumer products Lead in paint and pipes Radon Asbestos PBDE fire retardants

24 ChemicalSourcesTypeEffects ArsenicMining, Groundwater, Treated wood products CarcinogenCancer AsbestosBuilding InsulationCarcinogenLung Cancer RadonSoil, Water, BedrockCarcinogenLung Cancer Vinyl ChlorideIndustry, water from vinyl chloride pipes CarcinogenCancer, especially liver cancer PCBs (Polychlorinated biphenyls) Industry (electrical insulator, fire retardant, pesticides, adhesives) CarcinogenCancer PhthalatesUsed in production of plastics and as solvents CarcinogenReproductive damage and cancers Bisphenol AUsed in production of plastic bottles and food containers CarcinogenReproductive cancers BenzeneEmissions from burning coal, tobacco smoke CarcinogenCancer DioxinsClass of chemical compounds in manufacturing of some herbicides CarcinogenBioaccumulates, causes cancer

25 ChemicalSourceTypeEffects ThalidomideMorning Sickness Medication prescribed in the early 1960s TeratogenBirth Defects AlcoholAlcoholic beveragesTeratogenFetuses with reduced fetal growth, brain damage BenzeneEmissions from burning coal and oil, tobacco smoke TeratogenLong term exposure can cause birth defects Vinyl ChloridePrecursor to making PVC TeratogenBirth Defects The drug thalidomide, used to relieve nausea during pregnancy, turned out to be a potent teratogen, and caused thousands of birth defects before being banned in the 1960s.

26 ChemicalSourceTypeEffect LeadPaint, gasolineNeurotoxinNS disorders, Death MercuryCoal burning, fish consumption, batteries, fluorescent lights, smelting, incineration of municipal waste NeurotoxinBrain damage Heavy Metals (lead, mercury, Arsenic, Cadmium) Neurotoxin/TeratogenBiomagnify through food chain and cause neuological damage especially in fetuses PCB’sIndustry, electrical insulators, fire retardants, adhesives, pesticides Neurotoxin/TeratogenBrain damage, especially in fetuses Vinyl ChloridePrecursor to PVCNeurotoxinBrain damage Bisphenol APlastic bottles and containers NeurotoxinNeurological damage Link – Minamata Disease

27 ChemicalSourceTypeEffect AtrazineHerbicidesEndocrine DisruptorFeminization of males, low sperm count, damage to sexual development, reduced penis size, having both male and female sex organs DDTPesticideEndocrine DisruptorBiomagnifies, reproductive damage, thin egg shells, cancers in birds PhthalatesProduction of plastics, solvent in some cosmetic products Endocrine DisruptorFeminization of males, low sperm count, damage to sexual development, reduced penis size, having both male and female sex organs Frogs show reproductive abnormalities in response to small doses of the herbicide atrazine, researcher Tyrone Hayes has found. Others suggest that atrazine may have effects on humans as well, lowered sperm count, may also be linked to increasing incidence of breast and testicular cancers.

28 Endocrine Disruptor

29 Well Known Case Studies Love Canal Housing Development in Niagara Falls, New York – Hazardous waste chemicals buried in old canal leaked into homes, school yard, soil, and ground water. Led to the passage of Comprehensive Environment Response Compensation and Liability Act (CERCLA) aka “Superfund Act”

30 Well Known Case Studies Minamata, Japan – mental impairments, birth defects, and deaths caused by mercury dumped in Minamata Bay by a factory. The mercury was converted to methylmercury, bioaccumulated in fish, and biomagnified through food chains. Mercury entered humans who ate a traditional fish based diet.

31 Know Well Known Case Studies Bhopal, India – On December 2, 1984, poisonous methyl isocyanate gas was released accidentally by a Union Carbide pesticide plant killing about 5,000 people and causing serious health effects for 50, ,000.

32 Risk Risk = the mathematical probability that some harmful outcome will result from a given action, event, or substance Probability = a quantitative description of the likelihood of a certain outcome Harmful outcome could be defined as injury, death, environmental damage, economic loss, etc.

33 Perception different from reality Our perception of risks tends not to match statistical reality. smoking plane crash

34 Risk assessment Analyzes risks quantitatively Measures and compares risks involved in different activities or substances Helps identify and prioritize serious risks Helps determine threats posed to humans, wildlife, ecosystems

35 Risk assessment Involves: Dose-response analysis or other tests of toxicity Assessing likely exposure to the hazard (concentration, time, frequency)

36 Risk management Consider risk assessments in light of social, economic, and political needs and values. Weigh costs and benefits, given both scientific and nonscientific concerns. Decide whether or not to reduce or eliminate risk.

37 Risk assessment and risk management inform policy Following risk management, policy decisions are made.

38 Philosophical approaches “Innocent until proven guilty”: Assume harmless until shown to be harmful Precautionary principle: Assume harmful until shown to be harmless

39 Implications for product testing “Innocent until proven guilty”: Industry can introduce any products it wants. Government bears the burden of proof to show if products are dangerous. Precautionary principle: Industry cannot introduce a product until it is very thoroughly tested and shown convincingly to be harmless.

40 Implications for product testing Industry has pressured government to take an “innocent- until-proven-guilty” approach. Environmental advocates have pressured government to follow the precautionary principle.

41 Stockholm Convention In 2001, a group of 127 nations gathered in Stockholm, Sweden, to reach an agreement on restricting the global use of some chemicals 12 chemicals were to be banned, phased out, or reduced (aka “dirty dozen”) These include DDT, PCBs, and certain chemicals that are by-products of manufacturing processes. International Treaty – Persistent Organic Pollutants Treaty (POPs) Signed but not ratified by United States

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