Correlation of Fat Content and Dioxins, Total Mercury and Methyl Mercury Levels in Tuna

Abstract

In this study, we analyzed the concentrations of mercury and dioxins in tuna with various fat contents (akami; the leaner meat, Chutoro; the belly area of the tuna along the side of the fish between the akami and the otoro. Otoro; the fattiest portion of the tuna) in wild and farmed bluefin tuna and farmed southern bluefin tuna. In the three kinds of tuna, average dioxins concentrations in Akami, chutoro and otoro were 1.7, 4.7 and 9.6 pg TEQ/g, respectively. The dioxins concentration in all three regions of tuna was in direct proportion to the fat content. In the farmed bluefin tuna, the dioxins concentration was almost the same as that of the wild tuna, but di#ered from that of the farmed southern bluefin tuna. Average total mercury concentration based on wet weight in akami was 0.42 ῌg/g, being higher than the values of 0.36 ῌg/g of chutoro and 0.31 ῌg/g of otoro, and in inverse proportion to the fat content. In all three regions, the total mercury concentration of the wild bluefin tuna was equal to that of the farmed tuna. The total mercury concentration in the latter was two to three times higher than that of the farmed southern bluefin tuna. If the Japanese intake is one fin of tuna (80 g) a day, the daily intake levels of dioxins and methyl mercury can be estimated as 0.48ῌ37 pg TEQ/kg bw and 0.21ῌ0.90 ῌg/kg bw, respectively.

Monitoring of metal content in the tissues of wild boar (Sus scrofa) and its food safety aspect

“…Kawakami et al ( 2010 ) studied the concentrations of mercury in three kinds of tuna (wild bluefin tuna, farmed bluefin tuna, and farmed southern bluefin tuna) with various fat contents (akami, chutoro, otoro). The concentrations of mercury in the leaner part of the tuna (akami) were 0.42 µg/g and 0.36 µg/g in the “intermediate” part of the tuna (chutoro) and 0.31 µg/g in otoro with the highest fat content.…”

Determination of Hg in Farmed and Wild Atlantic Bluefin Tuna (Thunnus thynnus L.) Muscle

“…Generally, the levels of Hg and Se found in our study are well consistent with the reported data, although the differences in size/weight make the comparisons less precise. Concerning mercury, farmed tuna show similar levels compared with the same species and same area: all farmed reports show Hg values well below the legal limit [20,50,51]. For wild Thunnus thynnus, our study confirms that Mediterranean tuna have Hg levels higher than tuna coming from other areas such as Australia or Japan [20,40], even compared to other tuna species, such as T. albacares, T. alalunga, T. obesus that usually spend their time life principally in the Atlantic, Pacific and Indian oceans, coming rarely into the Mediterranean Sea, known as a Hg-rich basin [52].…”

“…Possible relations with biometric parameter were also considered. Few studies have been carried out on this species to assess the comparison of mercury content between farmed and wild specimens [19,20] and, to the best of our knowledge, this is the first study on Atlantic bluefin tuna (ABFT).…”