Ecological Evaluation Technical Guidance - State of New Jersey

Sample SelectionAfter completing the toxicity test phase of the bioaccumulation study,investigators should determine whether the tissue samples should besubmitted for COPEC analysis. When choosing test tissue samples to submitfor analysis, it is important to select only tissue from those soil or sedimentsamples that showed no significant reduction in organism survival, ascompared to the laboratory control or reference sample. If survival issignificantly reduced, bioaccumulation is not the primary concern. If asignificant percentage of the organisms exposed to a soil or sediment sampledid not survive the test period, it is highly likely that the tissue COPEC burdenaccumulated by the surviving organisms would not be representative andcould be misleading. It is also important to include only those test organismsthat survived the entire test period for tissue analysis. All dead organismsshould be recorded and discarded. Inclusion of dead organisms in tissueanalysis would not be representative and could bias the study.Tissue Mass RequirementsDepending on the list of COPECs, the analytical tissue mass requirement maybe quite high (50 to 70 grams per sample for a full suite of organic andinorganic analytes).Marine/estuarine bioaccumulation studies with oligochaete worms (e.g.,Nereis virens or Neanthes arenacoedentata) or bivalves (e.g., clams, musselsor oysters) can easily be designed to yield sufficient tissue mass because thetest organisms are relatively large. This allows analysis of tissue samplesfrom individual test replicates, allowing robust statistical comparison of eachsediment sample. However, freshwater bioaccumulation studies are typicallyperformed with much smaller polychaete worms (e.g., Lumbriculusvariegatus) or bivalves (e.g., fingernail clams, Corbicula fluminea).Individual L. variegatus weigh approximately 0.015 grams, requiringthousands of worms to make up a 50-gram tissue mass requirement. Becauseit is not feasible to set up multiple replicate samples with thousands of worms,it is best to limit use of L. variegatus to sediment samples with COPEC listswith a small analytical tissue mass requirement.Some bioaccumulation studies with soil organisms (e.g., earthworms orplants) can easily be designed to yield sufficient tissue mass because the testorganisms can be relatively large. Testing can be initiated with worm speciesthat are large enough to yield sufficient tissue at test termination. Plantbioaccumulation studies can be performed using species that will growsufficiently by test termination to yield the desired tissue mass. This allowsanalysis of tissue samples from individual test replicates, allowing robuststatistical comparison of each soil sample. The portion of plant to be assayedneeds to be determined on a case by case basis. For example, if data are to beused for dietary exposure modeling, Arrow arum fruit is a preferred food ofwood ducks, and all portions of aquatic plants (e.g., roots, basal portions,stems, leaves) and basal portions of Phragmites can be consumed byEcological Evaluation Technical Guidance Document 44Version 1.2 8/29/12