Step 2: Summarize toxicological data

Step 2: Summarize toxicological data

This section summarizes currently available toxicological data and provides

toxicity factors as appropriate for the expressions of exposure. That is, the toxicity

factors must be expressed in the same manner as the exposures. For example,

exposures which are expressed as doses must have corresponding toxicity factors

also expressed as a dose.

The summary should identify the toxic end points (i.e., the effect associated with

each toxicity factor). The end points may include: lethality, reproductive

impairment, behavioral modifications, or various sublethal toxic effects. End points

may also include secondary effects such as loss of habitat. (As of this writing, the

most commonly observed end points for aquatic receptors are lethality and

reproductive impairment).

The types of toxicity factors often used include:

a. Lethal effects: Lowest reported or estimated nonlethal dose.

b. Reproductive or developmental effects: Lowest reported or estimated No

Observed Adverse Effect Level (NOAEL - the concentration, dose, or body

burden at which studies report no observed adverse effects) for reproductive

or developmental effects. Effects can include: reduction in eggshell

thickness, malformations of young, decrease in number of larvae or young

produced, embryotoxicity, and reduction in number of eggs.

c. Systemic effects: Lowest reported or estimated NOAEL. Examples include:

reduction in growth, hepatic enlargement, and other anatomical alterations

considered adverse.

Appendix D provides detailed toxicological profiles for the likely contaminants

of concern at dredged material management sites. The risk assessment should

include a toxicological profile for each COC. These should be updated based on a

query of information sources described in the text detailing Step 1.

Toxicological information may be derived from literature studies, Tier III and

Tier IV bioassays, in situ bioassays, and field studies. Each method has inherent

strengths and limitations. Information provided by various methods may include:

a. Concentrations or levels at which a COC elicits an adverse response in an

individual organism or, where possible, a population.

b. A description of how the response of a test organism varies with the dose of

a contaminant of concern (i.e., dose/response relationships).

c The type and magnitude of the response.

d. The identification of toxic end points.

Chapter 3 Ecological Exposure Assessment