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.)

• http://www.youtube.com/watch?v=NWm6PUGpfVU

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 1995-1999

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