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Water: Microbial

Thesaurus of Terms Used in Microbial Risk Assessment: 5.13 Ecological Risk Assessment Terms

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critical effect

The first adverse effect, or its known precursor, that occurs to the most sensitive species as the dose rate of an agent increases.  (EPA 2003, EPA 2005b)

ecological risk

In the context of risk assessment, the expected frequency or probability of undesirable (or “unacceptable adverse”) ecological effects resulting from exposure to known or expected stressors.  (Navy 2003)

ecological risk assessment
  1. The process that evaluates the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors.  (EPA 2004)
  2. The application of a formal framework, analytical process, or model to estimate the effects of human action(s) on a natural resource and to interpret the significance of those effects in light of the uncertainties identified in each component of the assessment process. Such analysis includes initial hazard identification, exposure and dose response assessments, and risk characterization.  (EPA 2005b, RAIS 2004)
effective concentration          (ACRONYM: EC50)

A concentration expected to cause an effect in 50% of a group of test organisms.  (EPA 1998a)

effective dose          (ACRONYM: ED10)

The dose corresponding to a 10% increase in an adverse effect, relative to the control response.  (EPA 2003)

exposure frequency
  1. The number of occurrences in a given time frame (e.g., a lifetime) of contact or co-occurrence of a stressor with a receptor.  (EPA 2004)
  2. The number of exposure events in an exposure duration.  (IPCS 2004)
exposure indicator

A characteristic of the environment measured to provide evidence of the occurrence or magnitude of a response indicator’s exposure to a chemical or biological stress.  (EPA 2005b, RAIS 2004)

indicator organisms

A species, whose presence or absence may be characteristic of environmental conditions in a particular area of habitat; however, species composition and relative abundance of individual components of the population or community are usually considered to be a more reliable index of water quality.  (SRA 2004)
RELATED TERMS: indicator, exposure-response

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measure of ecosystem and receptor characteristics

Measures that influence the behavior and location of organisms of interest, stressor distribution, and organismal life-history characteristics that may affect exposure or response to the stressor. (EPA 1998a)

measure of effect
  1. Describes change assessment endpoint (or surrogate) attributes in response to a stressor to which it is exposed.  Dose-response data are an example.  (EPA 1998a)
  2. A measurable characteristic of ecological entity that can be related to an assessment endpoint; e.g. a laboratory test for eight species meeting certain requirements may serve as a measure of effect for an assessment endpoint, such as survival of fish, aquatic, invertebrate, or algal species under acute exposure.  (EPA 2005b)
measurement endpoint
  1. A measurable ecological characteristic that is related to the valued characteristic chosen as the assessment endpoint.  Also known as “measure of effect.”  (EPA 2004)
  2. A measurable characteristic of ecological entity that can be related to an assessment endpoint; e.g. a laboratory test for eight species meeting certain requirements may serve as a measure of effect for an assessment endpoint, such as survival of fish, aquatic, invertebrate or algal species under acute exposure.  (EPA 2005b)
  3. Measurable (ecological) characteristic that is related to the valued characteristic chosen as an assessment point.  (IPCS/OECD 2004)
    RELATED TERMS: measure of effect
microenvironment method
  1. A method used in predictive exposure assessments to estimate exposures by sequentially assessing exposure for a series of areas (microenvironments) that can be approximated by constant or well-characterized concentrations of a chemical or other agent.  (EPA 1992)
  2. A method for sequentially assessing exposure for a series of microenvironments that can be approximated by constant concentrations of a stressor.  (EPA 2005b)
primary effect

An effect where the stressor acts on the ecological component of interest itself, not through effects on other components of the ecosystem (synonymous with direct effect; compare with definition for secondary effect).  (EPA 1998, 2005b)

prospective risk assessment

An evaluation of the future risks of a stressor not yet released into the environment or of future conditions resulting from an existing stressor.  (EPA 1998a)

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receptor
  1. Ecology:
    1. The ecological entity exposed to the stressor.  (EPA 1998, EPA 2005b)
    2. In fate/transport modeling, the location where impacts are predicted.  (EPA 2004)
    3. In a non-modeling context, the entity which is exposed to an environmental stressor.  (EPA 2004)
  2. Molecular biology: A molecule on the surface of a cell that serves as a recognition or binding site for antigens, antibodies or other cellular or immunologic components.  (NIAID 2000)
receptor population
  1. The exposed individual relative to the exposure pathway considered.  (EPA 1999B)
  2. People who could come into contact with hazardous substances.  (ATSDR 2004)
    RELATED TERMS: exposure pathway
retrospective risk assessment

An evaluation of the causal linkages between observed ecological effects and a stressor in the environment.  (EPA 1998a)

secondary effect

An effect where the stressor acts on one component of the ecosystem, which in turn has an effect on the component of interest (synonymous with indirect effects).  (EPA 1998a)
RELATED TERMS: contrast with primary effect

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stressor
  1. Any physical, chemical, or biological entity that can induce an adverse response.  (EPA 1998a)
  2. Physical, chemical, or biological entities that can induce adverse effects on ecosystems or human health.  (EPA 2005b)
  3. The term “stressor” includes the connotation that the adverse response can be the result of a lack of something – such as a habitat – which would also be called a “stressor.” The term “agent” does not have this connotation, and is only used to denote a causative entity that actually physically exists as part of the environment.  (IPCS 2001)
  4. Any entity, stimulus, or condition that can modulate normal functions of the organism or induce an adverse response (e.g., agent, lack of food, drought).  (IPCS 2004)
stressor-response profile

A summary of data on the effects of a stressor and the relationship of the data to the assessment endpoint.  (EPA 1998a)

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