Bioaccumulation of hexachlorobenzene in the terrestrial isopod Porcellio scaber

A test system to investigate the biomagnifcation of organic chemicals in the terrestrial isopod Porcellio scaber was developed and validated. Adult isopods were fed on alder leaf powder (Alnus glutinosa) spiked with [14C]hexachlorobenzene (HCB). Test animals, sampled regularly during the uptake (16 d) and depuration phases (16 d), were analysed and the kinetic of tissue concentrations determined. Uptake (k1) and depuration rates (k2) were calculated to estimate kinetic biomagnification factors (BMFs). Additionally, the effect of coprophagy on the uptake and accumulation of HCB as well as the tissue distribution of HCB in P. scaber was investigated. The test system showed to be suitable for investigations on the terrestrial bioaccumulation of chemicals. Coprophagy had no effect on the bioaccumulation of HCB in P. scaber. The hepatopancreas was identified as the main target tissue for HCB accumulation. The low biomagnification factor of 0.057 resulted from a low assimilation efficiency (a) of 31.42%, a low uptake rate k1 (0.009 d-1) as well as a high depuration rate k2 (0.164 d-1). The results indicate that the terrestrial bioaccumulation of organic chemicals in P. scaber might not represent a worst case scenario for biomagnification limiting the value of the test system for the regulatory assessment of organic chemicals.