Pharmaceuticals in the environment: from molecular interactions to alterations of physiological processes in the mussels, Mytilus galloprovincialis

Pharmaceuticals are present in the environment, particularly in aquatic ecosystems, and have been identified as contaminant of emerging concern considering their recent discovery or their long-term presence in the environment without identification or consideration as non-dangerous contaminants. This study was mainly focused on examining the effects of two types of pharmaceuticals on marine mussels, Mytilus galloprovincialis, i.e., antidepressant and antidiabetic drugs. Eight different concentrations (0.5-500 ng/L) were evaluated for their effects on early life stage endpoints i.e., fertilization success and embryonic development at 48h post-fertilization (hpf). Adult mussels were in vivo exposed to 0.5, 5, and 10 ng/L of each drug, and a battery of biomarkers was assessed namely lysosomal parameters and activity of enzymes. Further, this research also examined the in vitro intrinsic clearance of seven pharmaceuticals in liver S9 fractions from Atlantic salmon (Salmo salar) and common carp (Cyprinus carpio) according to OECD 319B guidelines. The results highlighted that SSRIs and SNRIs affected fertilization rates, while only SSRIs were found to cause embryotoxicity. Conversely, antidiabetic drugs did not affect early life stages. In adult mussels, all tested pharmaceuticals significantly affected lysosomal parameters. In contrast to the control group, SSRIs and SNRIs significantly altered lysosomal membrane stability by up to 70%, while antidiabetic drugs significantly altered this parameter by up to 36%. Furthermore, it was concluded that metabolites have negative effects similar to or greater than those of parent compounds. The Mussel Expert System determined that all compounds impaired mussel health status as indicated by the low to high-stress levels. According to the intrinsic clearance in fish species, it was assumed to be a species-specific process since there was difference for metabolism of the tested pharmaceuticals between two species. This will provide insight into these compounds' mechanisms of action, leading to a better understanding of physiology and endocrine disruption.