ieh2

• Environment


  Circumstances, objects, or conditions by which one is surrounded
• Environment


  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
• Health


  Flourishing condition or well-being, not just absence of disease
• Health


  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
• Safe


  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
• 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 toxins


  • Agriculture-food, water
• Asbestos-asbestosis, lung cancer


  • Insulation, auto brakes-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
• Epidemiology


  Study the occurrence of diseases in people who have been exposed to a natural or man-made factor in the environment
• Epidemiology


  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?
• Epidemiology


  • Study the distribution and determinants of health, morbidity, injuries, disability, mortality in populations
  • Examine associations between environmental hazards and health outcomes
  • Control of health problems in populations
• Toxicology


  The study of the adverse effects of chemical or physical agents on living organisms
• Paracelsus: '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
• For pollutants to have effect on health, they must be received in doses over long periods of time or on repeated occasions sufficient to trigger detectable symptoms
• Dose


  Quantity of substance in the body
• Absorbed Dose


  Amount of substance entering body as whole
• Target Organ Dose


  Amount reaching specific affected organs
• Toxicology Principles


  • 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 on hazardous nature of agents, degree of human exposure, and 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