Bioaccumulation of cadmium in muscle and liver tissues of juvenile Yellowfin tuna (Thunnus albacares) from the Indian Ocean.

Abstract The present study evaluated the cadmium (Cd) levels and temporal variation of Cd in dark muscle, white muscle, and liver of juvenile Thunnus albacares. 72 individuals (Standard length: 50 -67cm; weight: 0.8 kg - 2.5 kg) were collected from the selected landing sites in Sri Lanka during the period between April 2021 to May 2022. Total Cd levels were analyzed using an inductivity-coupled Coupled Plasma Mass Spectrophotometer. The mean Cd levels (mean ± SD mg/kg dry weight) in different tissues varied with significantly higher levels in the liver (13.62 ± 0.98, p < 0.05), compared to dark muscle (0.52 ± 0.05), and white muscle (0.42 ± 0.04). Cd levels in liver tissues were positively correlated (p < 0.05) with the fish weight. The highest Cd levels in liver tissue and dark muscle were reported in October 2021 (26.35 ± 3.46, 0.93 ± 0.10 mg/kg d.w. respectively) while in white muscle, the highest Cd level was found in November (0.60 ± 0.07 mg/kg d.w.). The Cd levels reported in dark muscles, white muscles, and liver tissues were significantly higher (p < 0.05) during 2nd inter-monsoon than in the other monsoonal regimes. The measured Cd levels (mg/kg wet weight) in white and dark muscles, were well below the maximum permissible level (0.2 mg/kg wet weight) set by WHO/FAO, but in the liver tissues of all samples were above the level. Accordingly, the edible flesh (white and dark muscles) of T. albacares from the Indian Ocean can be considered safe for human consumption whereas the liver tissues are unsafe. A human with a body weight of 60 kg can consume white muscles up to 4.667 kg per week without exceeding the Provisional Tolerable Weekly Intake defined by WHO/FAO.