Antibiotic residues and heavy metals in blue crabs (<i>Callinectes sapidus</i>) fished in the Mediterranean Sea: a preliminary study

In recent decades, the Mediterranean Sea has experienced the invasion of the blue crab (Callinectes sapidus), which threatens the marine ecosystem and economic activities related to fishing and aquaculture because of its aggressive behavior. Control strategies are being developed to reduce its population. In Italy, a partial solution to the problem is its promotion as a food product. However, to ensure consumer safety, promoting consumption must be accompanied by a careful risk analysis. This study aims to assess heavy metals and antibiotic residues in the appendage muscle of 18 blue crab samples from various Mediterranean sites, selected by sex and size. Heavy metals were quantified using inductively coupled plasma mass spectrometry, and antibiotics were analyzed with the liquid chromatography/triple-quadrupole tandem mass spectrometry multiresidue/multiclass method. In all samples, lead was never detected, while cadmium and mercury concentrations never exceeded the limit of 0.5 mg/kg set by Regulation (EU) 2023/915. Only one sample tested positive for the occurrence of 12 antibiotic residues. The results showed that the blue crab is a species commonly characterized by the accumulation of heavy metals, according to other studies. Therefore, monitoring the concentration of metals in these species is important for food safety and ecosystem management. Data on 12 antibiotic residues detected in a single crab sample require further investigation through extensive sampling in terms of both number and sites, involving a wider area along the Mediterranean Sea coast, to allow for proper risk characterization.