3._Enivironmental_Hazards_to_Human_Health

Environmental Hazards and Human Health

Major Health Hazards

• Risk: The probability of suffering harm from a hazard including injury, disease, death, or economic loss.

  • Possibility vs Probability:

    • Possibility: The event could happen.

    • Probability: The chances or odds of the event happening.

Role of Media in Risk

• The media influences the public perception of risk through information dissemination.

  • Example: Avian Bird Flu has resulted in no deaths in the U.S. while the common flu causes about 35,000 deaths annually.

Types of Hazards Humans Face

1. Biological Hazards

   • Over 1,400 known pathogens can infect humans (e.g., bacteria, viruses, parasites).

2. Chemical Hazards

   • Chemicals present in air, water, soil, and food (e.g., mercury in fish).

3. Physical Hazards

   • Natural disasters including fire, earthquakes, floods, hurricanes.

4. Cultural Hazards

   • Unsafe working conditions, unsafe highways, and poverty.

5. Lifestyle Choices

   • Choices like smoking, drinking, drug use, and inactivity.

Comparative Risk Analysis

High-Risk Health Problems

• Indoor air pollution

• Outdoor air pollution

• Worker exposure to industrial chemicals

• Toxins in drinking water

• Pesticides residues on food

Medium-Risk Problems

• Acid deposition, airborne toxic chemicals, ecological disturbances.

Low-Risk Problems

• Oil spills, groundwater pollution, thermal pollution.

Risk Perception and Management

• Risk analysis involves evaluating hazards, ranking risks, and determining mitigation strategies.

  • Factors affecting perception:

    • Greatest risk is poverty; lifestyle choices significantly impact health.

    • Recommendations: Avoid smoking, maintain healthy weight, limit alcohol, practice safe sex.

    • 2005 study suggests 1/3 cancer deaths could be avoided through these guidelines.

Technological Risk Estimation

• Estimating risk is complex; higher system complexity increases hazard prediction difficulty.

  • Example: Reliability = Technological Reliability x Human Reliability.

  • Historical examples: Chernobyl, Three Mile Island.

Challenges in Risk Evaluation

• Many ignore risks from enjoyable activities (e.g., motorcycle riding, smoking).

  • Factors influencing risk evaluation:

    1. Fear: Overestimates risk from rare events.

    2. Control: Higher fear over uncontrollable risks (e.g., flying vs driving).

    3. Type of Risk: Catastrophic vs chronic.

    4. Optimism Bias: Belief risks apply to others, not oneself.

    5. Instant Gratification: Choosing pleasurable actions despite known risks.

Biological Hazards Overview

Types of Diseases

• Non-transmissible Diseases: Caused by non-pathogens, develop slowly (e.g., heart disease, cancer).

• Transmissible Diseases: Can spread between humans (e.g., flu, HIV, malaria).

  • Pathways: Air, food, water, and unsanitary habits.

• Epidemic vs Pandemic: Epidemics are localized outbreaks; pandemics involve global spread.

Measuring Disease Impact

• Disability Adjusted Life Years (DALYs): New metrics for evaluating the burden of diseases.

Tuberculosis Threat

• Infects ~10 million globally yearly, with ~1.5 million deaths.

  • Treatment challenges due to patient non-compliance result in resistance.

• Control measures needed include improved screening and treatment in developing countries.

Viral Diseases

Common Viruses

1. Influenza (Flu)

   • Causes ~500,000 deaths yearly; pandemics can be lethal (1918 Spanish Flu example).

2. Hepatitis B (HBV)

   • Affects the liver, causing ~1.1 million deaths annually.

3. HIV

   • Infects ~1.7 million annually; major challenge in developing regions.

Chemical Hazards Overview

Types of Toxic Chemicals

1. Carcinogens: Cause/promote cancer, often with delayed effects.

2. Mutagens: Damage DNA, potentially hereditary mutations.

3. Teratogens: Cause birth defects in developing embryos.

Effects of Exposure to Chemicals

• Affected Systems: Immune, nervous, and endocrine systems—with specific examples of neurotoxins and endocrine disruptors.

Evaluating Chemical Risks

• Toxicology: Study of harmful chemical effects.

  • Dose impacts: Variable response based on age, size, and genetics.

  • Solubility and persistence: Impacts on environment and human health.

Mitigation Strategies for Chemical Hazards

• Encourage regulatory measures for toxic chemical releases and promote alternatives.

• Implementation of the Precautionary Principle—act to reduce risks even amid scientific uncertainty.

Smoking and Public Health

• Major preventable cause of death, contributing to ~400,000 deaths annually in the U.S.

  • Quitting at younger ages dramatically improves health outcomes.

  • Public health interventions can reduce smoking prevalence.