Unique physicochemical properties of perfluorinated compounds and their bioconcentration in common carp Cyprinus carpio L.

Carp (Cyprinus carpio L.) was exposed to perfluorinated compounds (PFCs)-perfluoroalkyl carboxylic acids (number of carbon atoms, C = 8, 11, 12, 14, 16, and 18) and perfluorooctane sulfonate (PFOS)-in bioconcentration tests to compare the bioconcentration factors (BCFs) and physicochemical properties of each specific compound. Despite having the same number of carbon atoms (C = 8), the BCFs of perfulorooctanoic acid (PFOA) and PFOS differed by more than two orders of magnitude (PFOA BCF = < 5.1 to 9.4; PFOS BCF = 720 to 1300). The highest BCFs were obtained from perfluorododecanoic acid (BCF = 10,000 to 16,000) and perfluorotetradecanoic acid (BCF = 16,000 to 17,000). The longest observed depuration half-lives were for perfluorohexadecanoic acid (48 to 54 days) and PFOS (45 to 52 days). The concentrations of PFCs were highest in the viscera, followed by the head, integument, and remaining parts of the test fish. PFCs concentrations in the integument, which was in direct contact with the test substances, were relatively greater than that of other lipophilic substance (hexachlorobenzene). It is likely that Clog P would be a better parameter than log K (ow) for the prediction of BCFs for PFCs. Threshold values for PFCs bioaccumulation potential (molecular weight = 700, maximum diameter = 2 nm) seemed to deviate from those generally reported because of the specific steric bulk effect of molecule size.