Low mercury, cadmium and lead concentrations in tuna products from the eastern Pacific

Abstract

Tuna species: Skipjack ( Katsuwonus pelamis ), yellowfin ( Thunnus albacares ) and bigeye ( Thunnus obesus ) are mainly processed into canned products (loins, solid pack, flakes) either in water or oil, and pre-cooked frozen loins. The National Institute of Fisheries of Ecuador (ISO/IEC 17025 certified), which is the official control laboratory, samples and analyses production batches of companies exporting to the European Union in order to ensure the quality control of Ecuadorean tuna product. From 2009 to 2016, 2572 samples have been analysed (by standard methods) for mercury, cadmium, and lead. The averages were 0.24 ± 0.14; 0.03 ± 0.03 and 0.05 ± 0.05 mg kg −1 (wet weight) respectively; which are well below the norms; i.e., total mercury: 1 mg kg −1 ; Lead: 0.3 mg kg −1 and Cadmium: 0.1 mg kg −1 according to the EU maximum limits. Over time mercury levels in the sample seemed to decrease but for cadmium and lead no clear pattern was observed. Additionally; samples of tuna can products taken at random from local vendor stores gave concentrations of: Mercury: 0.043 ± 0.004 mg kg −1 ; Cadmium: 0.012 ± 0.002 mg kg −1 ; Lead: below detection limit (0.01 mg kg −1 ). There were a few cases (15 out of 2572: 0.58%) of samples with readings near or just over-limit concentrations; of these, 12 corresponded to Cd, two to Pb and one to Hg. Some of them can be considered statistical outliers as well as cross contamination during analytical procedures. Raw tuna samples have given similar or lower concentrations. No significant statistical correlation was found between Hg, Cd and Pb values, this would suggest that the bioaccumulation of each metal is independent of each other. Literature reports that surface dissolved Hg, Cd, and Pb in the eastern Pacific are in the range of 2–18 ng kg −1 . Assuming suggested bioaccumulation of 2–6 times, the end concentration in the tuna would be 0.012–0.042; 0.036–0.108 and 0.010–0.027 μg kg −1 of Hg, Cd, and Pb respectively, that would be one order (or more) below the safe consumption limit. Most, if not all the tuna processed in Ecuador is captured in the eastern Pacific and within its EEZ. Ecuadorian canned tuna complies with stringent standards for presence of these metals; therefore, it can be considered safe to be consumed from the point of view of these metal concentrations. However, further studies should assess metal concentrations exclusively from Ecuadorian tuna captured close to coastal and insular areas.

How brand attitude, brand quality, and brand value affect Thai canned tuna consumer brand loyalty

“…These included concerns about the product's susceptibility to mercury poisoning, killing of dolphins from tuna nets, overconsumption, and higher prices ( Ferdman, 2014 ). However, in an eight year study from 2009 – 2016, Ormaza-González et al. (2020) determined that although there were low levels of cadmium, lead, and mercury discovered in tuna canned in Ecuadorian canneries, all levels were well below the maximum concentrations allowed by the reported literature.…”

Heavy metals content in fresh tuna and swordfish caught from Hindian and Pacific Oceans: Health risk assessment of dietary exposure

“…Ormaza-González et al . [ 63 ] reported that the highest accumulation of heavy metals, including Cd, occurred in the liver of tuna fish. However, this part was rarely consumed, indicating that its adverse effect was negligible.…”

“…Furthermore, the daily tolerable Cd intake per kg body weight, specified by this agent, was 0.83 g. This indicated that yellowfin tuna and swordfish caught from Pacific and Hindian Oceans were safe for consumption, as they contained a low level of Cd. Ormaza-González et al [63] reported that the highest accumulation of heavy metals, including Cd, occurred in the liver of tuna fish. However, this part was rarely consumed, indicating that its adverse effect was negligible.…”

Baseline study for the total mercury determination in Yemeni fish

“…As a result, mercury concentrations vary across the environment, including air, water, soil, and living organisms [ 4 ]. The relative toxicity of mercury is determined by its chemical form, and for methylmercury being one of the most poisonous compounds causing irreversible damage to the nervous system [ 5 , 6 ].…”

“…Human exposure to mono methylmercury (MMHg), the predominant form of mercury in fish due to biomagnification in the marine food chain, is primarily through fish intake [ 6 , 7 ]. The presence of mercury in fish can be especially dangerous for pregnant women, nursing mothers, and small children [ 4 ].…”