Biochemical Responses of Mytilus galloprovincialis to Individual and Binary Exposures to PFDoA, Bisphenol A and Tricresyl Phosphate: Exposure and Post-exposure Dynamics.

This study investigated the biochemical responses of the mussel Mytilus galloprovincialis both immediately after exposure (14 days) and following a subsequent recovery period (14 days) in uncontaminated conditions. Mussels were exposed to bisphenol A (BPA), perfluorododecanoic acid (PFDoA), and tricresyl phosphate (TCP), either individually at a nominal concentration of 20 ng/L or in binary mixtures containing 20 ng/L of each compound (40 ng/L total nominal concentration). Biomarkers of aerobic metabolism, energy reserves, antioxidant defences, esterase-mediated biotransformation, oxidative damage, and cholinergic function were assessed at the end of both periods. At the end of exposure, BPA was associated mainly with reduced electron transport system activity, PFDoA with modulation of antioxidant responses, and TCP with increased lipid peroxidation and altered acetylcholinesterase activity. After transfer to clean seawater, some responses approached period-specific control values, whereas others persisted or became more evident. BPA-exposed mussels retained lower aerobic metabolic capacity; PFDoA-exposed mussels showed continued modulation of glutathione peroxidase and total antioxidant capacity; TCP-exposed mussels retained elevated lipid peroxidation and incomplete restoration of acetylcholinesterase activity; and the TCP/PFDoA treatment showed increased metabolic, carboxylesterase and antioxidant responses. Binary exposures modified the biochemical profiles in an endpoint-dependent manner, but the design does not permit formal classification as additive, synergistic, or antagonistic. Because exposure concentrations and tissue burdens were not analytically verified, the mechanistic interpretation of persistence and recovery is limited. Overall, post-exposure responses were only partially reversible and differed among endpoints, supporting the inclusion of post-exposure periods and period-specific controls in ecotoxicological assessments.