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Risk Assessment

Planning an Ecological Risk Assessment

Planning - There is a need to make judgments early when planning risk assessments regarding the purpose, scope, and technical approaches that will be used. To simplify our discussion of planning the following structure focuses on ecological risk assessment. This website also presents more detailed information on human health and ecological risk assessment.

Risk assessors will typically ask the following questions when planning a human health risk assessment:

Who/What/Where is at risk?

  • Individual
  • General population
  • Lifestages such as juveniles or adults
  • Population subgroups — highly susceptible (for example, due to genetics) and/or highly exposed (for example, based on geographic area)
  • Different species — mink, for example, are highly susceptible to PCBs

What are the environmental hazards of concern?

  • Chemicals (single or multiple/cumulative risk)
  • Physical (changes to a habitat)
  • Microbiological or biological (disease or invasive species)
  • Nutritional (for example, fitness or metabolic state)

Where do these environmental hazards come from?

  • Point sources (for example, smoke or water discharge from a factory; contamination from a Superfund site)
  • Non-point sources (for example, automobile exhaust; agricultural runoff)
  • Natural sources

How does exposure occur?

  • Pathways (recognizing that one or more may be involved)
    • Air
    • Surface Water
    • Groundwater
    • Soil
    • Solid Waste
    • Food

  • Routes (and related human activities that lead to exposure)
    • Ingestion (both food and water)
    • Contact with skin
    • Inhalation
    • Non-dietary ingestion (for example, preening/grooming behavior)

What does the body do with the environmental hazard and how is this impacted by factors such as life-stage, genetics, species differences, 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?

What are the ecological effects?

Example of some ecological effects include, but are not limited to, changes in reproductive rates, tumors, effects on the nervous system, and mortality.

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 or embryonic development, juvenile stages, adulthood)?

Next Step is Phase 1

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