Toxicity of explosive compounds to the marine mussel, Mytilus galloprovincialis, in aqueous exposures

Lethal and sublethal effects 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 separate water only exposures to the Mediterranean mussel (Mytilus galloprovincialis). Toxicity endpoints included survival and byssal thread formation in adults, and larval development success of embryos, in 96- and 48-h exposures, respectively. The larval development endpoint was over an order of magnitude more sensitive to TNT compared to adult survival, with median effective concentration (EC50) values of 0.75 and 19.5 mg L−1 (3.30 and 74.1 μmol L−1), respectively. Byssal thread formation (48 h EC50=6.57 mg L−1; 29.3 μmol L−1) was also impaired at sublethal concentrations. The highest RDX and HMX concentrations tested (28.4 and 1.9 mg L−1 [124 and 6.43 μmol L−1], respectively) failed to promote any significant toxicological effect in exposed mussels. Median lethal residues (LR50) of 14.0 μg g−1 (51.0 nmol g−1) ww for TNT in the adults were similar to those measured for other marine invertebrates in previous studies, while body residues as high as 19.6 and 0.92 μg g−1 (86 and 3.1 nmol g−1) ww were not associated with any toxicity for RDX and HMX, respectively.