Environmental Health and Safety

• Environment


  • The trees, air, & soil around us
  • All places we live, work & play
  • Our fields, farms & the food we grow
  • Our oceans, lakes, and rivers
• Health


  • Nutritious food help us stay healthy
  • Regular exercise helps us strong and healthy
  • Doctors, hospitals, & medicines helps us get healthy if we're sick
• Environmental Health


  • The study of how environment affects your health
  • Focuses on external factors that cause disease, including elements of the natural, social, cultural, and technological words
  • Addresses all the physical, chemical, and biological factors external to a person, and all the related factors impacting behaviors
  • It compasses the assessment and control of those environmental factors that can potentially affect health
  • It is targeted towards preventing disease and creating health-supportive environments
  • The branch of public health concerned with monitoring or mitigating those factors in the environment that affect human health and disease
  • The condition of the environment in a particular region, especially as regards ecological diversity or pollution
• Three basic disciplines that contribute to the field of Environmental Health

  • Environmental epidemiology
  • Toxicology
  • Exposure science
• Environmental Epidemiology


  Relationship between environmental exposures (exposures to chemicals, radiation, microbial agents, etc.) and human health
• Toxicology


  How environmental exposures lead to specific health outcomes
• Exposure Science


  Human exposure to environmental contaminants; identification and quantification of exposure
• Rachel Carson's "Silent Spring"


  • Environmental science book
  • Detrimental effects of indiscriminate use of pesticides to the environment
  • DDT - Dichlorodiphenyltrichloroethane, Organochloride known for its insecticidal properties
• Seven Core Concepts in Environmental Health

  • Toxicity
  • Exposure
  • Dose/Response
  • Individual Susceptibility
  • Risks & Benefits
  • Environmental Justice
  • Community Resources & Action
• Public Health


  • All organized measures (whether public or private) to prevent disease, promote health, and prolong life among the population as a whole
  • Its activities aim to provide conditions in which people can be healthy and focus on entire populations, not on individual patients or diseases
• Three Main Functions of Public Health

  • The assessment and monitoring of the health of communities and populations at risk to identify health problems and priorities
  • The formulation of public policies designed to solve identified local and national health problems and priorities
  • To assure that all populations have access to appropriate and cost-effective care, including health promotion and disease prevention services
• Examples of Public Health Campaigns

  • Vaccination and control of infectious diseases
  • Motor-vehicle safety
  • Safer workplaces
  • Safer and healthier foods
  • Safe drinking water
  • Healthier mothers and babies and access to family planning
  • Decline in deaths from coronary heart disease and stroke
  • Recognition of tobacco use as a health hazard
• Mortality


  Mortality rate (death rate) is a measure of the number of deaths (in general, or due to a specific cause) in a population, scaled to the size of that population, per unit of time
• Morbidity


  Morbidity rate, which refers to the number of individuals in poor health during a given time period (the prevalence rate) or the number of newly appearing cases of the disease per unit of time (incidence rate)
• Epidemiology


  • The study of the factors that cause or encourage diseases
  • The study of the distribution and causes of disease and injuries in human populations
• Toxicology


  • The study of how toxicants cause adverse effects on living organisms
  • Science dealing with property, action, toxicity, fatal dose, detection, estimation of poisons, and interpretation of the result of toxicological analysis
• Toxin (Poison)


  • A chemical capable of producing a harmful reaction in a living organism
  • Toxins damage or kill living organisms because they react with cellular components to disrupt metabolic functions
• Paracelsus (1493-1541)


  • "All things are poison and nothing is without poison, only the dose permits something not to be poisonous"
  • "The dose makes the poison"
• Examples of Toxicants


  • Prenatal alcohol abuse (fetal alcohol syndrome)
  • Mercury in fish (brain damage)
  • Lead in paint (brain damage)
  • Dioxin poisoning (facial scarring)
• Dose


  The amount, usually per unit body mass, of a toxicant to which an organism is exposed
• Response


  The effect on an organism resulting from exposure to a toxicant
• Median Lethal Dose (LD50)

  The dose which is expected to kill 50% of the population in the particular group
• Median Effective Dose (ED50)

  The dose that produces a desired response in 50% of the test population when pharmacological effects are plotted against dosage
• Thresholds


  An important concept pertinent to the dose–response relationship is that of threshold dose, below which there is no response
• As the dose increases


  The percent of individuals who respond increases
• Absorption, Distribution, Metabolism, and Excretion (ADME)


  Once a living organism has been exposed to a toxin, the compound must get into the body and to its target site in an active form in order to cause an adverse effect
• Absorption


  The ability of a chemical to enter the blood (blood is in equilibrium with tissues)
• Distribution


  The process in which a chemical agent translocates throughout the body
• Target Organs


  Adverse effect is dependent upon the concentration of active compound at the target site for enough time
• Mechanisms of Action


  Adverse effects can occur at the level of the molecule, cell, organ, or organism
• Excretion


  Toxins are eliminated from the body by several routes including urinary excretion, exhalation, biliary excretion via fecal excretion, and others
• Metabolism (Biotransformation)


  The process by which the administered chemical (parent compounds) are modified by the organism by enzymatic reactions
• Key Organs in Biotransformation

  • Liver (high)
  • Lung, Kidney, Intestine (medium)
  • Others (low)
• Biotransformation Pathways


  • Phase I - make the toxicant more water soluble
  • Phase II - Links with a soluble endogenous agent (conjugation)
• Toxicology


  The study of how toxicants cause adverse effects on living organisms
• Harmful or Adverse Effects


  Those that are damaging to either the survival or normal function of the individual
• Toxicity


  Describes the degree to which a substance is poisonous or can cause injury. The toxicity depends on a variety of factors: dose, duration and route of exposure, shape and structure of the substance
• Chemical agents


  More water soluble and easier to excrete
• Decrease lipid solubility


  Decrease amount at target
• Increase ionization


  • Increase excretion rate
  • Decrease toxicity