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Dietary Uptake of Highly Hydrophobic Chemicals by Rainbow Trout (Oncorhynchus Mykiss)
Citation:
Burkhard, L., T. Lahren, K. Hanson, A. Kasparek, AND D. Mount. Dietary Uptake of Highly Hydrophobic Chemicals by Rainbow Trout (Oncorhynchus Mykiss). ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY. Springer, New York, NY, 85(4):390-403, (2023). https://doi.org/10.1007/s00244-023-01038-6
Impact/Purpose:
Purpose Models for bioaccumulation of organic chemicals by fish are well developed for chemicals of low to moderate hydrophobicity, but the uptake, accumulation, and elimination of highly hydrophobic chemicals is not well studied or understood, and is a major uncertainty in bioaccumulation modeling and environmental risk assessments relying on those models. This paper describes a dietary exposure of rainbow trout to several highly hydrophobic chemicals. Bioaccumulation of these chemicals is described, and contrasted with literature data for chemicals with a range of hydrophobicities. Audience The accuracy of tools used for bioaccumulation assessments of organic chemicals by OW, OPPT, OPP, and other partners need improvement for perfluorinated chemicals. Bioaccumulation of highly hydrophobic chemicals is a particularly difficult uncertainty that will be informed by this research. Impact The measurements from this study will aid in the improvement of models for predicting bioaccumulation of highly hydrophobic chemicals. These chemicals are of intense interest to EPA and regulatory agencies across the globe due to their persistence, bioaccumulative, and toxicity properties.
Description:
Rainbow trout (Oncorhynchus mykiss) was exposed through the diet to a mixture of non-ionic organic chemicals for 28 d, followed by a depuration phase, in accordance with OECD method 305. The mixture included hexachlorobenzene (HCB), 2,2',5,5'-tetrachlorobiphenyl (PCB-52), 2,2',5,5'-hexachlorobiphenyl (PCB-153), decachlorobiphenyl (PCB-209), decabromodiphenyl ether (BDE209), decabromodiphenyl ethane (DBDPE), bis-(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (TBPH), perchloro-p-terphenyl (p-TCP), perchloro-m-terphenyl (m-TCP), and perchloro-p-quaterphenyl (p-QTCP), the latter six of which are considered highly hydrophobic based on n-octanol/water partition coefficients (KOW) greater than 108. All chemicals had first-order uptake and elimination kinetics except p-QTCP, whose kinetics could not be verified due to limitations of analytical detection in the elimination phase. For HCB and PCBs, the growth-corrected elimination rates (k2g), assimilation efficiencies (α), and biomagnification factors (BMFL) corrected for lipid content compared well with literature values. For the highly hydrophobic chemicals, elimination rates were faster than the rates for HCB and PCBs, and α's and BMFLs were much lower than those of HCB and PCBs, i.e., ranging from 0.019 to 2.8%, and from 0.000051 to 0.023 (g-lipid/g-lipid), respectively. As a result, the highly hydrophobic organic chemicals were found be much less bioavailable and bioaccumulative than HCB and PCBs. Based on the current laboratory dietary exposures, none of the highly hydrophobic substances would be expected to biomagnify, but Trophic Magnification Factors (TMFs) > 1 have been reported from field studies for TBPH and DBDPE. Additional research is needed to understand and reconcile the apparent inconsistencies in these two lines of evidence for bioaccumulation assessment.
URLs/Downloads:
DOI: Dietary Uptake of Highly Hydrophobic Chemicals by Rainbow Trout (Oncorhynchus Mykiss)
https://pubmed.ncbi.nlm.nih.gov/37910193/