Bioaccumulation of explosive compounds in the marine mussel, Mytilus galloprovincialis

The bioaccumulative potential of the explosive compounds, 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) were assessed in water only exposures with the Mediterranean mussel (Mytilus galloprovincialis). Toxicokinetics experiments provided uptake rates, elimination rates, biological half-lives, and bioconcentration factors (BCFs). Kinetic BCFs were 1.61, 0.87, and 0.44, for TNT, RDX, and HMX, respectively, and confirmed the expected low bioaccumulative potential of these weakly hydrophobic compounds based on log Kow. Because apparent steady-state conditions were observed within the 4 h uptake period, steady-state BCFs were also calculated, and were within 20% of kinetic BCFs. TNT was rapidly biotransformed to aminodinitrotoluenes within minutes, while no transformation products were measured for RDX or HMX. Uptake clearance rates varied among the compounds, while elimination rates and associated half-lives were extremely fast (0.15–0.49 h). It is unlikely, based on these data, that exposure conditions for these explosive compounds in the marine environment pose unacceptable risks to mussels, and it appears that potential for trophic transfer is quite low.