Select and Evaluate Assessment and Measurement End Points

Sometimes the assessment end point cannot be directly measured. In such cases,

the risk assessment uses a measurement end point which is a measurable biological

response to a contaminant that can be used to make inferences about the assessment

end point. For example, an assessment end point might be sustaining fishery

diversity and abundance while its related measurement end point is a measure of the

community structure of the fish populations near a dredged material management

site.

How Are Assessment and Measurement End Points Used in Ecological Risk

Assessment?

The ecological risk assessment uses the assessment end points and measurement

end points to decide whether there is risk due to a specific dredged material

management activity based on whether the activity will alter the assessment or

measurement end point beyond some acceptable limit.

What Are Some Common Assessment and Measurement End Points?

Some commonly used assessment end points include: Sustained aquatic

community structure, including species composition and relative abundance and

trophic structure; sufficient rates of survival, growth, and reproduction to sustain

populations of carnivores typical for an area; sustained fishery diversity and

abundance.

Some common measurement end points include: Community analyses of benthic

invertebrates; body burdens of contaminants associated with a particular effect;

sediment concentrations with a known effect; and the results of a toxicity test.

Select and Evaluate Assessment and Measurement

End Points

An assessment end point is an explicit expression of the actual environmental

value to be protected (USEPA 1992a) during the management of the dredged

materials. The term applies only to ecological risk assessment. The environmental

values most commonly refer to valuable ecological resources that:

a. Are critical to the normal functioning of an ecosystem such as a diverse

benthic community structure.

b. Provide critical resources such as a fishery or sensitive habitat.

c. Are perceived as valuable by humans such as endangered species.

Sometimes the assessment end point cannot be directly measured. In such cases,

the risk assessment uses a measurement end point which is a measurable biological

response to a contaminant that can be used to make inferences about the assessment

end point. For example an assessment end point might be sustaining fishery

diversity and abundance while its related measurement end point is a measure of the

Chapter 2 Problem Formulation