Use of tissue and sediment‐based threshold concentrations of polychlorinated biphenyls (PCBs) to protect juvenile salmonids listed under the US Endangered Species Act

Abstract

Under the Endangered Species Act, the National Marine Fisheries Service has authority to protect listed species from any adverse actions that may jeopardize the population's ability to recover and increase to sustainable levels. Listed salmon species in the northwest United States are known to travel through urban areas in their migration from river to ocean. Species such as the chinook salmon (Oncorhynchus tshawytscha) often spend several weeks in these urban estuaries where they can be highly exposed to urban‐related contaminants that reside in the sediments and accumulate in their prey species. The concern is that these contaminants are bioaccumulated to levels that may impact the ability of individual salmon to grow and mature normally. This paper provides a framework for determining the tissue and sediment concentrations of polychlorinated biphenyls (PCBs) that are likely protective against adverse effects in listed salmonid species. The relevant ecotoxicological literature was examined and 15 studies were selected that met the pre‐established criteria outlined here. For each study, the lowest tissue concentration (residue) of total PCBs associated with a biological response was selected. The tissue concentration associated with the 10th percentile of these 15 studies was chosen to represent the residue effect threshold (RET) above which wild juvenile salmonids would be expected to exhibit adverse sublethal effects from accumulated PCBs. This value (2.4 μg PCBs g−1 lipid) is expressed in terms of the lipid‐normalized concentration because of the large effect lipid can have on the expressed toxicity and the substantial variability in lipid content observed in salmonids over their life cycle. A sediment concentration that is expected to produce the RET was then determined using the biota‐sediment accumulation factor approach. The sediment effect threshold, which varies with the total organic carbon content in sediment, is the level above which adverse effects may be expected in juvenile salmonids due to accumulation of PCBs from environmental exposure. Bioaccumulation of PCBs was examined in one river system as a model for determining an appropriate bioaccumulation factor for wild juvenile chinook salmon. Evaluation of exposure to potentially deleterious concentrations of PCBs based on tissue residues is the preferred approach; however, the sediment effect threshold may also be used in cases where bioaccumulation has been characterized in an estuary. The threshold values presented here are intended as interim guidelines that should be modified as more data become available. Additionally, because of the uncertainty around many of the factors and assumptions that comprise the single threshold effect values, it is recommended that future studies be employed to help determine a range of acceptable values that would afford protection under various environmental and biological conditions. Published in 2002 by John Wiley & Sons, Ltd.

Bioaccumulation of polychlorinated biphenyls in juvenile chinook salmon (Oncorhynchus tshawytscha) outmigrating through a contaminated urban estuary: dynamics and application

“…For example, Meador et al (2002) proposed that a tissue concentration of 2.4 lg tPCBs/g lipid was a protective tissue quality guideline (TQG) for salmonids. This TQG describes the 10th percentile of a variety of adverse biological responses for nonembryonic salmonids (fry to adult) that was compiled from several research studies.…”

“…Even though organismal lipid likely had little effect on the magnitude of bioaccumulation of PCBs for these fish (e.g., Stow et al 1996), we believe that tissue lipids will be a factor in determining the toxic response. As proposed elsewhere (Lassiter and Hallam 1990), the lipid content of tissue controls the proportional availability of accumulated hydrophobic toxicants and therefore the magnitude of the toxic response, which is a factor we considered when developing the tPCB TQG for salmonids (Meador et al 2002).…”

“…All fish for a given region over years (except 2000) were combined (years 2001-2004). Equation 2 used to determine sed oc guideline values using BSAF and tissue guideline (2.4 lg/g lipid) for salmonids from Meador et al (2002). Mean whole-body juvenile chinook lipid was 1% wet weight and 50th percentile for organic carbon (OC) for each side was 1.6% dry wt mass, which resulted in very high percentage increases in total PCB burden.…”

“…For these calculations we used a mean whole-body lipid content of 1% wet weight (Table 2) and the 50th percentile for organic carbon (OC), which was 1.6% dry wt for each side of the waterway. We selected the PCB tissue toxicity guideline of 2.4 lg/g lipid for salmonids from Meador et al (2002) for conversion to sediment values.…”

Presence and distribution of PAHs, PCBs and DDE in feed and sediments under salmon aquaculture cages in the Bay of Fundy, New Brunswick, Canada

“…The absorption efficiency of PCBs by salmon has been estimated at 50-75% by Meador et al (2002) and confirmed in a field study (Jacobs et al, 2002). The absorption of PAHs by trout exposed through the diet to fluorene and three heteroaromatic compounds of similar physical-chemical properties to aNAs was shown to increase over time and can reach levels higher than 100% of daily dose, after 4 months exposure (Hellou et al, 2002b).…”