Total mercury and arsenic concentrations in edible and non-edible tissues of Iranian tuna fish

Abstract

The concentration of total mercury (Hg) and arsenic (As) has been measured in edible and non-edible tissues (flesh, viscera, gill, skin, fin and tail) of two species of tuna fish including 15 yellowfin (Thunnus albacares) and 15 skipjack (Katsuwonus pelamis). They were fished from Chabahar port, the Oman Sea, Iran, in April-May 2011. Atomic absorption spectrometer equipped with cold vapour and hydride generation system was used to determine total concentrations of Hg and As after microwave digestion. Based on the results, the highest and the lowest Hg contents (wet weight basis) in yellowfin and skipjack were observed in viscera (1.29±0.06 and 1.15±0.04 μg/g), and fin and tail (0.48±0.04 and 0.30±0.08 μg/g), respectively. Furthermore, the highest level of As accumulation in yellowfin and skipjack was found in skin (1.99±0.35 and 2.17±0.20 μg/g, respectively), while the lowest was measured in fin and tail (0.19±0.04 and 0.23±0.03 μg/g, respectively). Most yellowfin samples had significantly more heavy metals than skipjack samples (P<0.05). Total Hg and As levels of the flesh of fish were found to be lower than the maximum permissible limit set by the European commission and the United States Environmental Protection Agency. Therefore, the complete separation of edible and non-edible tissues during the process of canning tuna fish is critical.