Toxicity assessment of organophosphorus in Ruditapes decussatus via physiological, chemical and biochemical determination: A case study with the compounds γ-oximo- and γ-amino-phosphonates and phosphine oxides.

Organophosphorus derivatives are widely used in human health care and have been detected in aquatic ecosystems. These compounds may pose significant risks to non-target exposed organisms and only limited studies are available on bioconcentration and the effects of organophosphorus derivatives on marine organisms. The aim of this work was to evaluate the possible toxic effects of two concentrations (20 and 40 µg/L) of γ-oximo- and γ-amino-phosphonates and phosphine oxides in mediterranean clams Ruditapes decussatus exposed for 14 days using different biomarkers and the changes of filtration and respiration rate. The use of clams in ecotoxicity evaluation is thus mandatory to assess the feasibility of assessing oxidative stress on R. decussatus after being exposed to γ-oximo- and γ-amino-phosphonates and phosphine oxides. The oxidative status was analyzed by measuring oxidative stress biomarkers RNS and ROS production in mitochondria, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferases (GSTs), lipid peroxidation (LPO) and acetylcholinesterase (AChE), whose alteration was indicative of organophosphorus exposure, in both gills and digestive gland of the clams. No significant alterations in RNS, ROS production, SOD, CAT and AChE activities and MDA content were observed in both organs of clams treated with γ-oximophosphine oxides. It was possible then to hypothesize that γ-oximophosphine oxides may have probably exerted an incomplete alteration of antioxidant defenses and damage, which was changed by the activation of defense mechanisms. On the contrary, oxidative stress parameters were changed after exposure to γ-amino-phosphonates and phosphine oxides. In addition, metals accumulation, filtration and respiration rates were altered following exposure to all the studied organophosphorus compounds.