8.1.2 Regulatory Considerations

regulatory protocols are not designed to address the unique characteristics that

occur as sediments dry and colonize with wetland or terrestrial plants and animals.

Also, the plant and animal routes of exposure are different and are treated

differently in this manual. It is USACE policy that the procedures used in this

manual provide a basis for determining if bioaccumulation poses a risk of effects

on populations of receptors of concern outside the CDF.

The UTM is concerned only with effects outside the CDF. Therefore, in the

UTM animal bioaccumulation is of concern only if it is part of a complete

exposure pathway from the dredged material to predators that live outside the site

and feed on organisms that bioaccumulate COC from the dredged material in the

site. To illustrate the concept, in the context of the UTM there is typically not a

concern about COC

Bioaccumulation by:

Unless:

Earthworms in terrestrial

A bird flies in from offsite and eats the

habitats within a CDF

worms

Fish in aquatic habitats within

A person catches and eats the fish, or a

a CDF

bird flies in from offsite and eats the fish

Mussels in wetland habitats

A raccoon comes onto the site and eats

within a CDF

the mussels

Because the concern in the UTM is for potential effects outside the site,

bioaccumulation is considered a component of exposure for off-site ROC, and is

not evaluated as an indicator of potential effects on the on-site organisms that may

accumulate the COC directly from the dredged material. This emphasis on effects

of bioaccumulation on predators is in contrast to the OTM and ITM, in which

bioaccumulation data have frequently been evaluated in relation to potential

effects on the organism whose tissues contain the COC rather than on the

predators of that organism.

Unlike the other contaminant mobility pathways addressed in the UTM, there

are presently no standards or criteria that can be directly applied in a technically

sound manner to animal (or plant) bioaccumulation. Therefore, bioaccumulation

is evaluated on the basis of its potential to cause effects on ROC populations

outside the CDF (Section 2.2.4). The exception to evaluation on the basis of

effects on ROC populations outside the CDF is when the ROC are humans or

endangered species, in which case there is concern about effects on individuals

within or outside the CDF.

The first step in determination of the potential for effects is to compare

bioaccumulation from the dredged material to bioaccumulation from a properly

selected reference material. If bioaccumulation from the dredged material is not

statistically greater than bioaccumulation from the reference material,

bioaccumulation is not considered to pose a potential for effects. If

bioaccumulation from the dredged material is statistically greater than from the

reference material, further evaluation in subsequent tiers is necessary to determine

the potential for effects. Because the reference material is carefully selected to

represent acceptable conditions, whatever bioaccumulation it may cause is an

8-2

Chapter 8

Animal Bioaccumulation