Dietary Bioaccumulation
of Perfluorophosphonates and
Perfluorophosphinates in Juvenile Rainbow Trout: Evidence of Metabolism
of Perfluorophosphinates
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Abstract
The perfluorophosphonates (PFPAs) and perfluorophosphinates
(PFPiAs)
are high production volume chemicals that have been observed in Canadian
surface waters and wastewater environments. To examine whether their
occurrence would result in contamination of organisms in aquatic ecosystems,
juvenile rainbow trout (<i>Oncorhynchus mykiss)</i> were
separately exposed to a mixture of C6, C8, and C10 monoalkylated PFPAs
and a mixture of C6/C6, C6/C8, and C8/C8 dialkylated PFPiAs in the
diet for 31 days, followed by 32 days of depuration. Tissue distribution
indicated preferential partitioning to blood and liver. Depuration
half-lives ranged from 3 to 43 days and increased with the number
of perfluorinated carbons present in the chemical. The assimilation
efficiencies (α, 7–34%) and biomagnification factors
(BMFs, 0.007–0.189) calculated here for PFPAs and PFPiAs were
lower than those previously observed for the perfluorocarboxylates
(PFCAs) and perfluorosulfonates (PFSAs) in the same test organism.
Bioaccumulation was observed to decreased in the order of PFSAs >
PFCAs > PFPAs of equal perfluorocarbon chain length and was dependent
on the charge of the polar headgroup. Bioaccumulation of the PFPiAs
was observed to be low due to their rapid elimination via metabolism
to the corresponding PFPAs. Here, we report the first observation
of an <i>in vivo</i> cleavage of the carbon–phosphorus
bond in fish, as well as, the first <i>in vivo</i> biotransformation
of a perfluoroalkyl acid (PFAA). As was previously observed for PFCAs
and PFSAs, none of the BMFs determined here for the PFPAs and PFPiAs
were greater than one, which suggests PFAAs do not biomagnify from
dietary exposure in juvenile rainbow trout