Cuantificación de los niveles de arsénico y mercurio en sushi de restaurantes y grandes superficies de la Comunidad Autónoma de Madrid

Abstract

Background: Environmental contamination, due to anthropogenic activities, is one of the most important issues affecting our 21st century society. Arsenic and mercury figure prominently in this context. These are heavy metals with a high capacity for bioaccumulation in various animal and plant species and can reach humans from their incorporation into the trophic chain. Cereals such as rice can absorb the arsenic present in the soil and some species of predatory fish concentrate the mercury from surface waters. These facts match with the boom of sushi consumption experienced in the last five years among Spanish population. If amounts of arsenic and mercury present in this Asian dish are high, their consumption on a regular basis can contribute to increase exposure to both heavy metals. Objetives: Quantify arsenic and mercury in sushi samples acquired in Asian restaurants and large supermarkets in the Comunidad de Madrid using atomic absorption spectrometry. Establish if there are significant differences between the analyzed samples based on their composition and determine if the arsenic and mercury contents are correlated. Methodology: A descriptive cross-sectional observational study has been carried out on sushi samples acquired in 2020 and 2021, in Asian restaurants with at least three franchises and online sales, and in large supermarkets, located in the Comunidad de Madrid. A total of 190 samples of the three types of most consumed sushi by Spanish population processed: maki, nigiri and sashimi. They all included in their composition one of the following fish species: salmon, tuna and butterfish. Samples subjected to microwave pressure digestion have been analyzed by atomic absorption spectrometry. Arsenic has been quantified by graphite furnace and mercury by cold vapour. Conclusions: An arsenic concentration of 0.3715mg/kg and a mercury concentration of 0.0295mg/kg have been obtained on the analyzed samples. Although there are no maximum limits regulated in the EU for sushi as a food, none of its three components exceeded the values that apply to them individually.Products with nori seaweed contained more arsenic than products without it. Tuna sushi presented the highest concentrations of arsenic and mercury, so that in our study there is a relationship between the species of fish in the sample and the amount of both heavy metals. The presence of rice is not relevant to the levels of heavy metals studied in the analyzed samples. The sushi rice samples were the least contaminated with arsenic and mercury. Sushis served in restaurants reached a higher mercury level that the ones acquired in large supermarkets. We did not find any correlation between arsenic and mercury concentrations in the analyzed samples.