Among the radioactive pollutants Po-210 is the most substantial one in terms of seafood safety due to its efficient accumulation in marine animals and high irradiation of its alpha emission. Mercury is a highly toxic metal for both marine organisms and human beings. Biomagnification of MeHg (methylmercury) through marine food chains has made Hg concern of ecotoxicology and seafood safety. In the current study, the bioaccumulation of Po-210 and THg (total mercury) were determined in 20 mollusc species, including 8 bivalves, 7 gastropods and 5 cephalopods collected from the island of Gokceada in the northeastern Aegean Sea. The highest accumulation of Po-210 and Hg was seen in bivalves and cephalopods, respectively. Elevated Hg concentrations in all body parts (arms, mantle and viscera) were observed in octopus' species. The results of this study suggests that filter feeder bivalves and gastropods have a capacity to concentrate Po-210 in their bodies, whereas predator gastropods and cephalopods have a capacity to concentrate Hg in their bodies. 7.0 kg (3.2-14.2) bivalve flesh intake is adequate due to Po-210 ingestion in the studied region to reach 1 mSv which is the annual committed effective dose. Octopus consumption of 705 g in a week alone is needed to reach Provisional Tolerable Weekly Intake (PTWI) of mercury, 5 mu g kg(-1) body weight. Due to very low non-fish seafood consumption in Turkey there is no risk of Hg intake and alpha radiation of Po-210 above the limit values through mollusc consumption. (C) 2019 Elsevier Ltd. All rights reserved.