Environmental Health Topic 2

• The Environmental Protection Agency  an independent agency of the United States government tasked with environmental protection matters.  It was created to protect people and the environment from significant health risks, sponsors and conducts research, and develops and enforces environmental regulations.
• EPA uses risk assessment protect people and the environment from significant health risks, sponsors and conducts research, and develops and enforces environmental regulations, for example residents, recreational visitors, both children and adults. EPA also estimates risks to ecological receptors, including plants, birds, other wildlife, and aquatic life.
• At EPA, environmental risk assessments typically fall into one of two areas:

  • Human Health
  • Ecological
• Three Factors of Risk:

  1. How much of a stressor is present
  2. How much contact or exposure
  3. How it affects
• Planning and Scoping Question:

  Who/What/Where is at risk?

  • Individual
  • General population
  • Lifestages such as children, teenagers, pregnant/nursing women
  • Population subgroups - highly susceptible (for example, due to asthma, genetics, etc.) and/or highly exposed (for example, based on geographic area, gender, racial or ethnic group, or economic status)
• Planning and Scoping Question

  What is the environmental hazard of concern?

  • Chemicals (single or multiple/cumulative risk)
  • Radiation
  • Physical (dust, heat)
  • Microbiological or biological
  • Nutritional (for example, diet, fitness, or metabolic state)
  • Socio-Economic ( for example, access to health care)
• Planning and Scoping Question

  How does exposure occur?

  • Pathways (recognizing that one or more may be involved)
  • Air
  • Surface Water
  • Groundwater
  • Soil
  • Solid Waste
  • Food
  • Non-food consumer products, pharmaceuticals
  • Routes (and related human activities that lead to exposure)
  • Ingestion (both food and water)
  • Contact with skin
  • Inhalation
  • Non-dietary ingestion (for example, "hand-to-mouth" behavior)
• Planning and Scoping Question

  What does the body do with the environmental hazard and how is this impacted by factors such as age, race, sex, genetics, etc.?)

  • Absorption - does the body take up the environmental hazard
  • Distribution - does the environmental hazard travel throughout the body or does it stay in one place?
  • Metabolism - does the body break down the environmental hazard?
  • Excretion - how does the body get rid of it?
• Planning and Scoping Question

  What are the health effects?

  • Example of some health effects include cancer, heart disease, liver disease and nerve disease.​
• Planning and Scoping Question

  How long does it take for an environmental hazard to cause a toxic effect? Does it matter when in a lifetime exposure occurs?

  • How long?
  • Acute - right away or within a few hours to a day
  • Subchronic - weeks or months (for humans generally less than 10% of their lifespan)
  • Chronic - a significant part of a lifetime or a lifetime (for humans at least seven years)
  • Intermittent
  • Timing → is there a critical time during a lifetime when a chemical is most toxic (e.g., fetal development, childhood, during aging)?
• The 4 Step Risk Assessment Process:

  1. Hazard Identification
  2. Does-response assessment
  3. Exposure Assessment
  4. Risk Characterization
• Hazard Identification

  •  identify the types of adverse health effects that can be caused by exposure to some agent in question, and to characterize the quality and weight of evidence supporting this identification
  • process of determining whether exposure to a stressor can cause an increase in the incidence of specific adverse health effects
• Dose-Response Assessment

  • document the relationship between dose and toxic effect
• Dose-response relationship


  Describes how the likelihood and severity of adverse health effects (the responses) are related to the amount and condition of exposure to an agent (the dose provided)
• The same principles generally apply for studies where the exposure is to a concentration of the agent (e.g., airborne concentrations applied in inhalation exposure studies), and the resulting information is referred to as the "concentration-response" relationship
• Exposure-response relationship


  May be used to describe either a dose-response or a concentration-response, or other specific exposure conditions
• Typically, as the dose increases, the measured response also increases.
• Exposure Assessment

  • calculate a numerical estimate of exposure or dose
  • process of measuring or estimating the magnitude, frequency, and duration of human exposure to an agent in the environment, or estimating future exposures for an agent that has not yet been released
• EPA defines exposure as 'contact between an agent and the visible exterior of a person (e.g. skin and openings into the body)'.
• Two common scenarios for possible exposure are "Central Tendency" and "High End".
• Common Scenarios for Possible Exposure:

  • Central Tendency exposure is an estimate of the average experienced by the affected population, based on the amount of agent present in the environment and the frequency and duration of exposure.
  • High End exposure is the highest dose estimated to be experienced by some individuals, commonly stated as approximately equal to the 90th percentile exposure category for individuals.
• Three basic approaches for quantifying exposure:

  • Point of Contact Measurement - The exposure can be measured at the point of contact while it is taking place, measuring both exposure concentration and time of contact, then integrating them;
  • Scenario Evaluation - The exposure can be estimated by separately evaluating the exposure concentration and the time of contact, then combining this information;
  • Reconstruction - the exposure can be estimated from dose, which in turn can be reconstructed through internal indicators after the exposure has taken place.
• Risk Characterization

  • summarize and integrate information from the proceeding steps of the risk assessment to synthesize an overall conclusion about risk
  • conveys the risk assessor's judgment as to the nature and presence or absence of risks, along with information about how the risk was assessed, where assumptions and uncertainties still exist, and where policy choices will need to be made
• Principles of Conducting Risk Characterizations

  • Transparency 
  • Clarity
  • Consistency 
  • Reasonableness
• WHY RISK ASSESSMENT IS IMPORTANT?

  They help to:

  a. create awareness of hazard and risks

  b. identify who may be at risk

  c. determine whether a control program is required for a particular hazard

  d. determine if existing control measures are adequate or if more should be done

  e. prevent injuries or illness, especially when done at the design or planning stage

  f. prioritize hazards and control measures

  g. meet legal requirements where applicable
• WHEN SHOULD A RISK ASSESSMENT BE DONE?

  • Before new processes or activities are introduced.
  • Before changes are introduced to existing processes or activities, including when products, machinery, tools, equipment change or new information concerning harm becomes available.
  • When hazards are identified.
• The Levels of Prevention:

  1. Primordial Prevention
  2. Primary Prevention
  3. Secondary Prevention
  4. Tertiary Prevention
• PRIMORDIAL Prevention

  • This aims to avoid the emergence and establishment of the social, economic and cultural patterns of living that are known to contribute to an elevated risk of the disease.
  • It inhibits people from becoming high risk to prevent from developing themselves to high risk factor.
  • e.g: legislations, guidelines, and healthy policy formulations
• PRIMARY Prevention

  • It is the protection of health by personal and communal efforts to prevent involvement of the stage of susceptibility.
  • It aims to prevent disease occurrence by changing the susceptibility or reducing exposure for susceptible individuals.
  • e.g. (1) General Health Education and Promotion (2) Utilization of Health Services (3) Media Campaign (4) Provision of Warning and Labels (5) Specific Protective Measures like Immunization
• SECONDARY Prevention

  • This aims to reduce/slow the disease progression (early stages of the disease, i.e. pre-clinical and clinical stages), to prevent complications or to reverse communicability.
  • This involves curing the disease at the earliest possible stage and having assumptions that pathologic conditions brought about by the agent can be reversed.
  • e.g. (1) Early Detection through Screening either Clinical or Diagnostic and; (2) Prompt Treatment.
• TERTIARY Prevention

  • This aims at reducing long time dysfunction and impairment or to prolong life.
  • This prevention assumes that pathologic conditions are irreversible especially in the stage of disability of the disease (usually brought about from disease complications).
  • e.g. (1) Disability limitation through Physiotherapy; (2) Rehabilitating patients to have Self-sufficient role in the society or; (3) Periodic follow-ups to prevent relapses of the infection.
• An ecological risk assessment is the process for evaluating how likely it is that the environment might be impacted as a result of exposure to one or more environmental stressors, such as chemicals, land-use change, disease, and invasive species. Provides information to risk managers about potential adverse effects of different risk management decisions
• Who will be involved in planning?

  • decision makers or risk managers - staff in EPA or other federal agencies or state environmental offices who have legal authority to protect a resource
  • risk assessors and scientific experts - must be familiar with multiple fields of expertise including ecology, population biology, ecotoxicology, statistics, or chemistry and other specialties
  • interested parties or stakeholders - may include federal, state, tribal and municipal governments, industrial leaders, environmental interest groups, small-business owners, landowners, and other segments of society
• Planning

  
• Problem Formulation

  
• Analysis of Exposure and Effects

  
• Risk Characterization

  
• Communicate Results Risk Management

  
• Gather Data, Iterate, and Monitor

  
• Problem/Context Risks Options Decisions Actions Evaluation