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Environmental Health Case Studies • Environmental health is the branch of public health that is concerned with all aspects of the natural and built environment that may affect human health. • Environmental Health works make things like this The Frontline • CDC o Center for Disease Control • US Agency • WHO o World Health Organization • International Agency • FDA o Food and Drug Administration • US Agency • EPA o Environmental Protection Agency • US Agency • AZDEQ o Arizona Department of Environmental Quality • State Agency Transmissible vs. Nontransmissible • Transmissible: o A pathogen (bacterium, virus, or parasite) invades the body and multiples in its cells and tisses o These can be passed from one human to another through various pathways • Human to human • Mother to fetus and baby • Pet to human • Livestock and wildlife to human • Mosquitoes, ticks, flies (etc) to human • Food to human • Water to human • Air to huma • Nontransmissible: o NOT caused by a living organism and does not spread from one person to another o Diseases tend to develop slowly and have multiple causes • Heart disease, diabetes, asthma, emphysema, some cancers, and malnutrition Case Study: Growing Germ Resistance To Antibiotics • Rapidly producing infectious bacteria are becoming genetically resistant to widely used antibiotics • Watch the video: A Growing Threat • Other contributors are: o Human Global Travel o Overuse of pesticides Case Study: Tuberculosis • Tuberculosis kills 1.7 million people per year and could kill 25 million MORE people by 2020. • Why? • Watch: TB in Russia • Watch: Fully Resistant TB Case Study: Toxic Mold • A living source of indoor air pollution is toxic airborne spores of molds (fungal growths) and mildew that can cause: o o o o Headaches Allergic reactions Aggravation of asthma and other respiratory diseases Could be the single greatest cause of allergic reactions to indoor air • Watch video: Military Housing • Watch video: Mold Effect Case Study: Infectious Disease • Viral Diseases o Flu, HIV, and hepatitis B infect and kill many more people each year than highly publicized West Nile and SARS viruses. o The biggest potential killer is the influenza or Flu virus • Could lead to a pandemic killing millions of people in only a few months o 2nd biggest killer is HIV (highest current killer) • 4.9 million new people infected each year • 3 million killed annually o 3rd killer is Hepatitis B • Damages the liver and kills 1 million every year • Vaccinations o Watch Bill Gates Video: LD50 • LD stands for lethal dose • LD50 is the amount of any material, given all at once, which causes the death of 50% of a group of test animals. • LD50 is a means of measuring the short-term poisoning potential (acute toxicity) of a material. • Acute toxicity is the ability of a chemical to cause ill effects relatively soon after one oral administration or a 4-hour exposure to a chemical in air. • "Relatively soon" is usually defined as a period of minutes, hours (up to 24) or days (up to about 2 weeks) but rarely longer. • LD100 would indicate the dose at which the entire population would die What is the LD50 of this substance? • A dose of 500 units The Dose is Not The Same From One Species to Another • LD50s for dichlorvos, an insecticide commonly used in household pesticide strips, are listed below: o o o o o o o o o o Oral LD50 (rat): 56 mg/kg Dermal LD50 (rat): 75 mg/kg Intraperitoneal (injection into the body cavity) LD50: (rat) 15 mg/kg Inhalation LC50 (rat): 1.7 ppm (15 mg/m3); 4-hour exposure Oral LD50 (rabbit) 10 mg/kg Oral LD50 (pigeon:): 23.7 mg/kg Oral LD50 (rat): 56 mg/kg Oral (mouse): 61 mg/kg Oral (dog): 100 mg/kg Oral (pig): 157 mg/kg • NOTE: how you are exposed matters too. Risk Assessment • Risk = Hazard x Exposure Risk Assessment • The process that scientists and government officials use to estimate the increased risk of health problems in people who are exposed to different amounts of toxic substances. o Hazard Identification o Probability of risk • How likely is the event? o Consequences of risk • What is the likely damage? Risk Management Is… • Comparative risk analysis o How does it compare with other risks? • Risk Reduction o How much should it be reduced? • Risk Reduction Strategy o How will the risk be reduced? • Financial Commitment o How much money should be spent? Case Study: DDT • Rachel Carson o DDT o Wrote: Silent Springs o Exposed the dangers of DDT to wildlife populations (video) o Began the current “wave of conservation” o Instrumental in the US ban on DDT o "A Review of the Twenty Greatest Unfounded Health Scares of Present Times." • The report lists the ban on DDT as one of these unfounded scares, because - in the opinion of the American Council on Science and Health - the benefits of DDT's power to kill insects who may carry diseases that threaten humans outweigh the chemical's effects on wildlife and humans. In addition, ACSH questions whether DDT effects wildlife and humans adversely at all. o Despite the 1972 DDT ban, the effects of the chemical continue to be evident in wildlife populations • British Columbia orchards have been sprayed with pesticides for 40 years. • DDT levels in the eggs of birds in these orchards are remarkably higher than levels reported 20-25 years ago • which suggests that although DDT is not in use, the residue continues to affect these birds. • Questions remain: What are the real effects of DDT on the robins? Does it cause acute poisoning of adult birds, or does it have longer-term reproductive effects on their offspring? o Died of a heart attack in 1964 while weakened from radiation treatments for breast cancer that had spread to her liver. o The EPA was in part founded as a result of her life’s work Case Study: MTBE • • • • • • • • An additive to gasoline used as an oxygenate (reduced CO) MTBE is often introduced into water-supply aquifers by leaking underground storage tanks (USTs) at gasoline stations or by gasoline containing MTBE spilled onto the ground. The higher water solubility and persistence of MTBE cause it to travel faster and farther than many other components of gasoline when released into an aquifer MTBE gives water an unpleasant taste at very low concentrations, and thus can render large quantities of groundwater non-potable. Use in the US is declining in part because of its occurrence in groundwater and legislation favoring ethanol MTBE is biodegraded by the action of bacteria MTBE is not classified as a human carcinogen. researchers have limited data about the health effects of ingestion of MTBE. The United States Environmental Protection Agency (EPA) has concluded that available data are inadequate to quantify health risks of MTBE at low exposure levels in drinking water, but that the data support the conclusion that MTBE is a potential human carcinogen at high doses