Environmental Health Midterm: Key Topics and Concepts

Posted on Feb 20, 2025 in Biology

Environmental Health

Midterm Study Guide Topics

Week 1: Introduction to Environmental Health

Healthy People Environmental Health Objectives:

  • Outdoor air quality
  • Water quality
  • Toxics and waste
  • Healthy homes and healthy communities
  • Infrastructure and surveillance
  • Global environmental health

Environmental Health Threats:

  • Trash that fouls our beaches
  • Hazardous wastes (including radioactive wastes) leaching from disposal sites
  • Continuing episodes of air pollution
  • Exposures to toxic chemicals
  • Destruction of the land through deforestation
  • Global warming

The P’s of Environmental Health:

  • Pollution
  • Population
  • Poverty

Different types of pollutants: 3 main types of air pollutants:

  • Gases
  • Liquid Aerosols
  • Particles

Stages of Demographic Transition:

  • Stage 1: Mostly young population, High fertility and mortality rates, Small population
  • Stage 2: Decreasing mortality rates, High fertility rates, Rapid increase in population
  • Stage 3: Decreasing fertility rates, More even distribution of population according to sex and age, Impact of urbanization

Week 2: Environmental Epidemiology

4 study designs most frequently used in Environmental Epi:

  • Descriptive: Generate Hypotheses, Ask what, who, where, and when
  • Analytic: Test hypotheses (determine cause-effect), Answer why and how
  • Cross Sectional Study Design
  • Ecologic Study Design
  • Case Control Study Design
  • Cohort Study Design

Hill’s criteria:

  • Strength: According to Hill, the stronger the association between a risk factor and outcome, the more likely the relationship is to be causal.
  • Consistency: Have the same findings must be observed among different populations, in different study designs and different times?
  • Specificity: There must be a one to one relationship between cause and outcome.
  • Temporality: Exposure must precede outcome.
  • Biological gradient: Change in disease rates should follow from corresponding changes in exposure (dose-response).
  • Plausibility: Presence of a potential biological mechanism.
  • Coherence: Does the relationship agree with the current knowledge of the natural history/biology of the disease?

Week 3: Environmental Toxicology

Define toxicology: “study of the adverse effects of chemicals on living organisms”

Toxicity: degree to which something is poisonous”, Related to a material’s physical and chemical properties

Toxicant: Toxic substances that are human-made or result from human (anthropogenic) activity

Dose-response relationships: Lethal dose: Is “the dosage (mg/kg body weight) causing death in 50 percent of exposed animals” Used to compare the toxicities of different chemicals

Factors That Affect the Concentration and Toxicity of a Chemical:

  • Route of entry into the body
  • Received dose of the chemical
  • Duration of exposure
  • Interactions that transpire among multiple chemicals
  • Individual sensitivity

Process of Risk Assessment:

  • Hazard identification
  • Dose–response assessment
  • Exposure assessment
  • Risk characterization

What is Neurotoxicty?

Anatomically:

  • Central (Brain and Spinal Cord)
  • Peripheral (all other nerves)

Functionality:

  • Voluntary (to skeletal muscles)
  • Involuntary (to smooth muscles, glands, etc.)

What is Reproductive Toxicity?

Reproductive Hazard vs. Developmental hazard: alters ability to conceive a child

Developmental Hazard: Teratogenicity- alters the structure or function of the fetus/baby

Differing Affects in first trimester vs. 2nd and 3rd trimester:

First Trimester:

  • Greatest risk at 4-9 weeks gestation
  • Most susceptible to what causes physical defects
  • Delay in normal growth and development

Fourth month to birth:

  • Defects in brain development
  • Low birth weight
  • Urinary and reproductive system development