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Human Health and Environmental Risks

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Presentation on theme: "Human Health and Environmental Risks"— 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 Threshold = dose at which response begins
LD50 = 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 Chemical Sources Type Effects Arsenic Mining, Groundwater, Treated wood products Carcinogen Cancer Asbestos Building Insulation Lung Cancer Radon Soil, Water, Bedrock Vinyl Chloride Industry, water from vinyl chloride pipes Cancer, especially liver cancer PCBs (Polychlorinated biphenyls) Industry (electrical insulator, fire retardant, pesticides, adhesives) Phthalates Used in production of plastics and as solvents Reproductive damage and cancers Bisphenol A Used in production of plastic bottles and food containers Reproductive cancers Benzene Emissions from burning coal , tobacco smoke Dioxins Class of chemical compounds in manufacturing of some herbicides Bioaccumulates, causes cancer

25 Chemical Source Type Effects Thalidomide Morning Sickness Medication prescribed in the early 1960s Teratogen Birth Defects Alcohol Alcoholic beverages Fetuses with reduced fetal growth, brain damage Benzene Emissions from burning coal and oil, tobacco smoke Long term exposure can cause birth defects Vinyl Chloride Precursor to making PVC 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 Link – Minamata Disease
Chemical Source Type Effect Lead Paint, gasoline Neurotoxin NS disorders, Death Mercury Coal burning, fish consumption, batteries, fluorescent lights, smelting, incineration of municipal waste Brain damage Heavy Metals (lead, mercury, Arsenic, Cadmium) Neurotoxin/Teratogen Biomagnify through food chain and cause neuological damage especially in fetuses PCB’s Industry, electrical insulators, fire retardants, adhesives, pesticides Brain damage, especially in fetuses Vinyl Chloride Precursor to PVC Bisphenol A Plastic bottles and containers Neurological damage Link – Minamata Disease

27 Chemical Source Type Effect Atrazine Herbicides Endocrine Disruptor Feminization of males, low sperm count, damage to sexual development , reduced penis size, having both male and female sex organs DDT Pesticide Biomagnifies, reproductive damage, thin egg shells, cancers in birds Phthalates Production of plastics, solvent in some cosmetic products 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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