Levels of heavy metals in Octopus (Octopus vulgaris) from South Tyrrhenian: Preliminary Results

The common octopus (Octopus vulgaris) is a voracious predator normally distributed on rocky, sandy and muddy bottoms. It is characterized by fast growth rates and a short lifespan and known for its ability to accumulate high levels of elements essential to metabolic functions and nonessential elements. In general, feeding is considered to be the primary pathway for trace element bioaccumulation in cephalopods and second seawater. Although O. vulgaris is benthic, living in direct contact with the substratum, which represents another possible pathway for trace element accumulation. The objectives of the present study were to evaluate Cd, Pb and Hg levels in the muscle of octopus (Octopus vulgaris) collected from the southern Tyrrhenian Sea in Italy and to assess the health risk related to human consumption. Samples (n.12) of Octopus vulgaris were caught along the coast of the southern Tyrrhenian Sea between September and December 2015. Organisms were stored in individual plastic bags and immediately frozen onboard in order to minimize mobilization of metals between organs/tissues. Samples were kept at -25°C for a maximum of 2 weeks before dissection. In the laboratory, arm and mantle was dissected excluding the skin. Weight, mantle length and sex were determined for each individual and was subsequently homogenized by means of a laboratory mixer for metal analysis. Aliquots of each sample were digested in ultrapure 65% HNO3 and H2O2 in a microwave digestion system. Pb, Cd and Hg concentrations were determined by atomic absorption spectrometer (GF-AAS). Cd and Hg concentrations were found very low in all samples of octopus muscles (Cd: 0.011±0.018 mg/kg w.w.; Hg: 0.017±0.040 mg/kg w.w.) and were below the legal limit for human consumption. The concentration of Pb was generally high in samples of muscle (0.851±0.662 mg/kg w.w.) and all tested samples were above the maximum concentration level (Reg CE 1881/2006) excluding this product to human consumption. To establish possible human health implications related to consumption of octopus, the Pb estimate weekly intakes (ISMEA, 2010) were subsequently compared with the provisional tolerable weekly intake (PTWI) of 25 µg/kg of body weight (EFSA, 2010). Considering the level of Pb, the consumption of octopus muscle may increase Pb intake, but it would not contribute significantly to the PTWI. In contrast, may reach high EWI values in the heavy consumer of octopus, when the other main contributors to dietary Pb intake were included in the exposure assessment. The preliminary results obtained in the current study showed the presence of Pb in all samples analyzed, underlying its presence in the environment. Monitoring studies on heavy metals in Octopus vulgaris and other species of the marine food chain in a greater number will provide more detailed information of the human exposure to Pb in this area.