The acute and chronic toxicity of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) to three freshwater invertebrates

The acute and chronic toxicities of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) to adaphnid ( Ceriodaphnia dubia ), a hydra ( Hydra littoralis ), and a midge ( Paratanytarsus parthenogeneticus ) were examined. RDX concentrations at the solubility limit of the compound under specific test conditions (17.0 mg RDX/L, Ceriodaphnia dubia at 25°C; 32.3 mg RDX/L, Hydra littoralis at 22°C; and 29.2 mg RDX/L, Paratanytarsus parthenogeneticus at 22°C) were not acutely toxic to any of the three tested invertebrates. In a 7‐d survival and reproduction test with Ceriodaphnia dubia , RDX caused no significant effect on survival, but reduced reproductive success. The no‐observed‐effect concentration, lowest‐observed‐effect concentration, and chronic value for Ceriodaphnia dubia were 3.64, 6.01, and 4.68 mg/L, respectively. In an egg‐to‐egg life cycle test with Paratanytarsus parthenogeneticus , survival, growth, egg production, and hatching success were unaffected by RDX. Although not statistically significant, reductions in emergence success were observed at concentrations as low as 6.78 mg/L.