Human Exposure to Toxic Metals (Cd, Pb, Hg) and Nitrates (NO3−) from Seaweed Consumption

Abstract

Seaweed is now considered a functional food with a high nutritional value in Western countries, and the consumption of different species of edible algae has grown exponentially in recent decades. However, anthropogenic pressure on the seas has increased the presence of pollutants such as toxic metals and nitrates that can accumulate in algae. It is necessary to know the levels of these contaminants and the dietary exposure from the consumption of edible algae. The content of toxic metals (Cd, Pb, Hg) and nitrates (NO3−) was determined in 72 samples of edible algae marketed in the Canary Islands (Spain). Cd stands out in the Asian algae hijiki (1.196 mg/kg) and nori (1.005 mg/kg). Pb stands out in the Asian wakame seaweed (0.119 mg/kg). The highest mean concentration of Hg was in European arame algae (0.055 mg/kg). Some samples of the nori seaweed had NO3− concentrations of >8000 mg/kg. Considering the consumption recommended by the manufacturer of 4 g/day, the maximum admissible intake values are not exceeded, and, consequently, this does not pose a risk to health. However, in the case of Cd, Pb, Hg, and NO3−, legislation is necessary to regulate their content in edible algae.

Macroalgae in biomonitoring of metal pollution in the Bay of Bengal coastal waters of Cox’s Bazar and surrounding areas

“…This may be attributed to the high hygiene standards through the food supply chain and also during seaweed culture intended for human consumption. In markets from the Canary Islands (of Spain) reported Pb concentrations in seaweeds of Asian and European origin have ranged from 0.12 to 0.004 mg kg −1 and from < LOQ to 0.05 mg kg −1 , respectively 57 . The importation of potentially contaminated edibles as a source of heavy metal exposure has been discussed by others, including in regard to the consumption of seaweed.…”