Ecological and Human Health Risk Assessment Guidance

What Is the Purpose of this Document?

This document provides guidance for conducting ecological and human health risk assessments at aquatic

sites potentially impacted by dredged material management activities.

What is Risk Assessment?

Risk assessment is the process of evaluating the impact of a chemical or physical condition upon the

health of individual humans or the environmental well-being of a population or community of animals and

plants. The former is called human health risk assessment, and the latter ecological risk assessment.

Proper Timing for the Risk Assessment Option?

The project manager should decide to apply a risk assessment within the context of the site selection

process and/or the four-tiered evaluation of dredged material, or when there are unresolved issues with

regard to potential human or ecological exposures. It is most applicable to projects which have:

a. Reached Tier IV and concern about specific bioaccumulative compounds or toxic compounds

remains.

b. The potential to affect a local sensitive habitat or species.

c Outstanding exposure issues where a risk assessment will allow realistic use of information about a

species' natural history such as foraging areas, breeding times, migration patterns.

d. Potential human health exposure either directly to sediments or through the food chain.

e. Issues associated with environmental windows (time periods when a species is least vulnerable).

Who Can Conduct a Risk Assessment?

The selection of personnel to conduct a risk assessment depends on the level of complexity

addressed in the risk assessment. For example, a rough estimate of exposure based on a simple

sediment-water partitioning equation may be sufficient to demonstrate little probability of

bioavailability of a chemical, and hence risk. In such a case, operations personnel with expertise in

engineering, chemistry, or marine geology may be the only necessary personnel. In the most

complex assessments (and these are likely to be the least frequently encountered), an

interdisciplinary team of engineers, biologists, chemists, and physical scientists may be necessary.

Chapter 1 Overview of Ecological and Human Health Risk