ieh

• Determinants of health


  • Social and economic environment
  • Physical environment
  • Individual's characteristics and behaviors
• The environment is closely connected with human health, illness, and mortality
• 40% toll of world's deaths caused by environmental factors
• Environmental health problems are primarily the result of environmental degradation and exposures to potentially hazardous agents
• 3P's contributing to health


  • Pollution
  • Population
  • Poverty
• Current trend for world population growth


  1. Everyday, we share the world its resources with 250,000 than the day before

  2. Every year, 90 million people added: Philadelphia city every week

  3. Los Angeles every 2 weeks

  4. Mexico every year

  5. United Sates and Canada every 3 years
• Consequences of population growth


  • Urbanization
  • Exploitation of natural resources
  • Production of toxic wastes
  • Food insecurity
  • Loss of biodiversity
• Environmental health problems


  • Outdoor air pollution: respiratory infections, selected cardiopulmonary diseases, lung cancer
  • Indoor air pollution: COPD, lower respiratory infections, lung cancer
  • Lead: mild mental retardation, cardiovascular diseases
  • Water, sanitation, hygiene: diarrheal diseases, trachoma, schistosomiasis, ascariasis, trichiasis, hookworm disease
  • Climate change: diarrheal diseases, malaria, selected unintentional injuries, protein energy malnutrition
  • Selected occupation factors(injuries, noise): hearing loss, cancers, asthma, COPD, low back pain
• Toxicity


  • Toxic means poisonous or dangerous
  • Toxicity is a measure of how dangerous a chemical is
  • Toxicology is the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating exposures to toxins and toxicants
• Exposure


  Having contact with chemical, biological, or physical substances found in air, water, food, or soil that may have a harmful effect on a person's health
• Dose/response


  Describes the magnitude of the response of an organism, as a function of exposure (or doses) to a stimulus or stressor after a certain exposure time(duration, frequency and body size)
• Individual susceptibility


  Pregnant women and their developing babies, sick people who have weak immune system, elderly people whose defense mechanism are less efficient, infants and children who are still developing
• Risks and benefits of pesticides


  • No insects
  • More visually appealing
  • Bigger crops
  • Farmers make more profit
  • Health issues
  • Environmental pollution
• Everyone has the right to live in health env, regardless of their race, culture, income
• Environment


  • Circumstances, objects, or conditions by which one is surrounded
  • All that which is external to the individual host → physical, biological, social, and cultural factors → influence health status in populations
• Health


  • Condition of being sound in body, mind, or spirit
  • Flourishing condition or well-being, not just absence of disease
  • State of complete physical, mental, and social well-being and not merely the absence of disease or infirmity
• Disease


  Trouble or condition of living animal or plant body or one of its parts that impairs the performance of a vital function
• Safe


  • Free from harm or risk
  • Secure from threat of danger, harm, or loss
• Risk


  Possibility of loss, injury, peril
• Environmental health


  • Study of factors present in the environment and that affect human health: Agents present in air, water, soil, or food
  • Routes of human exposure
  • Adverse health effects
• Environmental factors


  • Chemical: toxic wastes, pesticides, food preservatives, chemicals used in residential and industrial operations
  • Biological: disease organisms present in food and water, insect and animal allergens
  • Physical: noise, heat, cold, radiation
  • Socioeconomic: income, adequate nutrition, employment, housing, access to safe and sufficient health care
• Routes of human exposure


  • Food: GI tract
  • Soil: GI tract, skin
  • Water: GI tract, skin
  • Air: lungs, skin
• Environmental exposures and health effects


  • L. pneumophila-legionnaire's disease-soil, cooling towers-air, building ventilation systems
  • Salmonella-acute diarrhea, human/animal feces, water, meat, eggs
  • Dioxin-chloracne, soft tissue tumors-herbicides, paper mills, incinerators-air, water, food
  • Pesticides-nervous system tox-agriculture-food, water
  • Asbestos-asbestosis, lung cancer-insulation, auto braker-air, water
• Adverse health effects


  • Exposure
  • Internal dose
  • Bio effective dose
  • Early biologic effects
  • Altered structure and function
  • Clinical disease
• Solving environmental health problems


  1. Determine source and nature of each environmental contaminant or stress

  2. Assess how and in what form that contaminant or stress comes into contact with people

  3. Measure resulting physical and economic impacts

  4. Apply controls when and where appropriate
• Facets of environmental health


  • Environmental epidemiology
  • Environmental toxicology
  • Risk assessment
• Epidemiology


  • Fundamental discipline used in the study of environmental health
  • Study the occurrence of diseases in people who have been exposed to a natural or man-made factor in the environment
  • Type of research that most health regulations are based on
• Environmental epidemiology questions


  • What environmental exposures might act in combination with genetic factors to cause breast cancer?
  • What are the health effects of consuming seafood contaminated with mercury?
  • Does secondhand cigarette smoke cause lung cancer in nonsmokers?
  • Are death rates higher in geographic regions that have higher air pollution levels in comparison with regions that have lower levels?
• Toxicology


  • The study of the adverse effects of chemical or physical agents on living organisms
  • What is there which is not a poison?
  • All things are poison and nothing without poison
  • Solely dose determines that a thing is not poison
• Toxicology objectives


  • Protect health and environment
  • Understand mechanisms of exposure and action
  • Recognize hazards in workplace and in environment
  • Treat poisoning and discover new drugs
  • Develop criteria and regulations
• Dose


  • Quantity of substance in the body
  • Absorbed dose: amount of substance entering body as whole
  • Target organ dose: amount reaching specific affected organs
• • The dose makes the poison
  • Nontoxic chemical can be toxic at high doses
  • Poisons are not harmful at a sufficiently low dose
  • Highly toxic chemicals can be life saving when given in appropriate doses
• • Within a population, the majority of responses to a toxicant are similar
  • A wide variance of responses may be encountered, some individuals are sensitive and others are resistant → individual susceptibility
• Dose response assessment


  • Determine causality → chemical has induced observed effects
  • Define threshold → lowest dose where an induced effect occurs, when body's ability to detoxify xenobiotic or repair toxic injury has been exceeded
  • Assess rate of injury build up
• Risk assessment


  • Systematic characterization of potential adverse health effects resulting from human exposure to hazardous agents
  • Assessments of risks to human health involves examination and evaluation of information in three areas: Hazardous nature of agents in the environment, Degree of human exposure to such agents, Impact of such exposure on people's health
• Risk assessment steps


  • Hazard identification
  • Hazard characterization
  • Exposure assessment
  • Risk characterization
• Environmental health professions


  • Water quality and protection
  • Food safety and quality
  • Solid and hazardous waste management
  • Air quality and pollution control
  • Soil science and land conservation
  • Occupational health and safety
  • Environmental education
• Access to sufficient, safe and nutritious food is key to sustaining life and promoting good health
• Unsafe food can cause more than 200 different diseases
• 600 million fall ill after eating contaminated food each year resulting in 420,000 deaths