A study investigating heavy metals in salmonids products marketed in Spain

Spain is the second European country that consumes the most fish, with salmon being the second most consumed. Therefore, the safety of salmonids for human health is a hot topic that requires more research. In this study we measured arsenic, cadmium, mercury and lead (As, Cd, Hg and Pb respectively) in 54 samples of four salmonid species ( Oncorhynchus gorbuscha , O. keta , O. mykiss and S. salar ) acquired in Asturias (North Spain) supermarkets, imported from other regions. O. mykiss samples (N = 30) from local farms located on two nearby rivers in the same region were also analyzed as well as river water. Marketed samples were authenticated through DNA barcoding. No species substitution was found, while five samples from O. keta exhibited contradictory information about the geographical origin in the label. The label indicated that they were from “Northwest Pacific” and “FAO area 67”. The Northwest Pacific catch zone corresponds to FAO 61, while FAO 67 is located in Northeast Pacific. Only one market sample exceeded the legal limit of Pb and none for other metals. Five S. salar samples from Denmark surpassed the safety limits marked for As, and other five samples from different species for Hg, but correcting for the expected proportion of the toxic form of these elements only three exceeded the safety limits for Hg and none for As. The importance of local contamination was emphasized for different metal profiles according to different content in water. Overall, health risk assessment indicate that salmonids sold in Spain can be considered safe for human consumption. • Labels correct for the species, but 16% with ambiguous geographic information. • Samples from the North Sea exhibited higher levels of arsenic. • Cadmium was detected only in North Pacific salmon products. • Low risk of heavy metal ingestion from farmed and wild salmonids. • Farming or catch location affects heavy metal content even at small local scale.