In March 2019 researchers from Spain published the results of their study to assess the content of toxic metals in edible seaweed samples marketed in Spain. A total of 73 European and Asian edible seaweed samples marketed in Tenerife were analysed to determine their content of aluminium, cadmium, lead and mercury. Results showed that the major toxic metal was aluminium, the highest level being recorded in seaweed salad. It was noted that the highest concentrations of aluminium, cadmium and lead were found in samples from Asia, which may be due to the high levels of industry in these countries, whilst the highest concentration of mercury was found in European seaweed. The consumption of 5g of dehydrated seaweed per day represented 22.7% of the tolerable weekly intake of cadmium which may pose a risk when considering total cadmium intake. However, despite this the researchers concluded that currently the consumption of 5g a day of dehydrated seaweed would not pose a risk to the health of adults.
Paz S et al. Toxic metals (Al, Cd, Pb and Hg) in the most consumed edible seaweeds in Europe. Chemosphere. 2019 Mar;218:879-884