Environmental Hazards, Risk, & Human Health

Leading Causes of Mortality

Public Health – Some Definitions Morbidity: incidence of disease in a population Mortality: incidence of death in a population Environment: combination of physical, chemical, and biological factors Hazard: anything that can cause injury, death, disease, damage to personal/public property, or deterioration or destruction of environmental components Risk: probability of suffering a loss as a result of exposure to a hazard

What Are Environmental Hazards? They Can Be: –Cultural (food choices, smoking, alcohol) –Biological (bacteria, fungi, viruses, etc.) –Physical (tornadoes, hurricanes, earthquakes) –Chemical (cleaning products, pesticides, fuels, etc.)

Biological Hazards Not generally a consequence of choice Causes: –Pathogenic bacteria –Fungi –Viruses –Protozoans –Worms Is drinking untreated water from a mountain stream a cultural or biological hazard?

TB 2001 Does the pattern on this map look anything like the patterns we saw elsewhere?

Malaria, 1996

Physical Hazards Weather-related: hurricane, tornado, flood, fire, etc. Non-weather-related: earthquake, tsunami, volcano Cannot be avoided, can be mitigated: –Building sites –Building design –Preparedness

Chemical Hazards Industrialization Increased Exposure Industrialization also Increased Awareness What’s Important? –Exposure: Inhalation, ingestion, skin absorption –Dose –Examples?

Potential Chemical Hazards in the Environment Urban Air: –lead –VOCs –NOx, sulfur oxides –Particulates –Ozone –CO Food and Water: –Pesticides –Heavy metals –Lead Indoors: –Particulates –CO –Asbestos (maybe) –Household product residues/fumes Land: –Heavy metals –Dioxins, PCBs, etc

What are the Concerns? Acute Exposure: immediate health consequences –Serious, but often easily treatable Chronic Exposure: health consequences over time –Serious, less easy to treat Carcinogenic: initiates changes in cells –Read about Carcinogenesis in the text

Example: Tobacco Use 442,300 deaths associated with smoking per year from

Toxic Risk Pathways Indoor Air Pollution: –Both developed and developing countries –Sources are furniture, equipment, paint, etc –Building are sealed (saves energy) –Population spends more time indoors Added Concern in Developing Countries: heat/cook with biofuels –Respiratory infections, lung disease, lung cancer, birth related problems Asthma and worms…

Risk Assessment What is it? –The process of evaluating risks associated with a particular hazard before taking some action where the hazard is present. –Any examples in your life?

Chemical Hazard Risk Assessment Historical Data – takes time Animal Testing –Is the animal a good model? –Cost –Ethical issues Chemical Structure –Chemical groups associated with hazards

Dose-Response Dose: concentration exposed to Response: effect LD50 –Lethal dose that causes 50% of organisms to be affected/die Another Problem: is the chemical hazard chemically distinct or mixture? –Benzene vs. gasoline –Nicotine vs. cigarette smoke

Exposure Who is exposed? How often? Route of entry? Dose? Duration? Food for thought: if you were exposed to the quantity of radiation received in your 3.75 HS years of television viewing in one minute, you would likely have negative consequences

Risk Characterization Using previous data (LD50, risk assessment, exposures) to determine risk and uncertainties Expressed as a probability of fatal outcome (risk factors for causes of disease, 14.9% underweight in LDC) EPA and cancer risk: – Clean Air Act (1990) requires regulation of chemicals with > 1/1,000,000 cancer risk

Risk Management Cost-Benefit Analysis: –Example: emission controls (cars-yes, lawnmower-no) Risk-Benefit Analysis: –Examples: medical X-rays, mountain biking Public Preference (risk perception) – tolerance for risks that they can control

Risk Perception Familiarity – bees vs. sharks Voluntary – driving car vs. contaminated drinking water Public Impression – coal vs. nuclear Morality – wrong to destroy a coral reef Control – driving car vs. airplane flight Fairness - coal mine neighbor vs. coal mine owner