Bioacumulação de As em tilápias (Oreochromis niloticus): fracionamento das espécies de arsênio inorgânico
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Data
2018-06-26
Autores
Ferreira, Nathalia dos Santos
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Universidade Estadual Paulista (Unesp)
Resumo
Um mercado que está em expansão é o de pescados, devido à busca por alimentos mais saudáveis e por conta do aumento do poder de compra da população. Entretanto, apesar dos inúmeros benefícios à saúde, os pescados podem estar expostos a diversos contaminantes inorgânicos, como é o caso do arsênio (As) que pode desencadear processos de bioacumulação nas espécies aquáticas por meio da cadeia alimentar. A determinação de As em amostras de pescado é de grande interesse analítico devido principalmente ao seu potencial de toxicidade, uma vez que seus efeitos estão intimamente relacionados às suas formas químicas e seus estados de oxidação, sendo que as formas inorgânicas de As (III) e (V) são mais tóxicas que as suas formas orgânicas. O presente trabalho teve como objetivo desenvolver e realizar ensaios de bioacumulação com As (III) e (V) em tilápias do Nilo (Oreochromis niloticus) sob condições controladas em laboratório, a fim de verificar a distribuição de As nos tecidos (fígado, estômago, brânquias e filé) e assim determinar parâmetros toxicocinéticos para avaliar a capacidade de absorção e depuração deste elemento nas tilápias. As determinações de As foram realizadas pela técnica de espectrometria de massas com plasma acoplado indutivamente (ICP-MS) no modo padrão, e a exatidão do método foi confirmada pelas análises dos materiais de referência certificados (NIST 1640a, SRM 1566a, DORM-3 e DOLT-4), com recuperações na faixa de 80 a 110%. As concentrações de arsênio total determinadas nas tilápias expostas ao As (III) e (V) pelos ensaios de bioacumulação variaram entre 0,06 – 8,79 µg g-1 nos fígados, 0,05 – 0,78 µg g-1 nos estômagos, 0,10 – 0,41 µg g-1 nas brânquias e 0,11 – 0,36 µg g-1 nos filés, evidenciando que o fígado e o estômago apresentaram maiores capacidades em absorver e acumular o contaminante. Também foi realizado um estudo de fracionamento de arsênio em tecidos de peixes e frutos do mar para avaliar a distribuição do arsênio nas fases lipídicas e proteicas, uma vez que existe uma correlação positiva entre o acúmulo de contaminantes e o conteúdo lipídico dos tecidos. No entanto, estudos adicionais precisam ser realizados para a otimização das metodologias de extrações lipídicas e proteicas, visto que os tecidos dos ensaios de bioacumulação apresentavam baixa concentração de arsênio, não apresentando as recuperações esperadas.
The fish market is expanding due to the search for healthier foods and because of the increase in the purchasing power of the population. However, despite the numerous health benefits, fish may be exposed to several inorganic contaminants, such as arsenic (As), which can trigger bioaccumulation processes in the aquatic species through the food chain. Thus, the determination of As in fish samples is of great analytical interest mainly due to its toxicity potential, since its effects are closely related to its chemical forms and their oxidation states, whereas the inorganic forms of As (III) and (V) are more toxic than organic forms. The aim of the present work was to develop and perform bioaccumulation assays with As (III) and (V) in Nile tilapia (Oreochromis niloticus) under laboratory conditions, in order to verify the distribution of As in tissues (liver, stomach, gills and fillet) and thus determine toxicokinetic parameters to evaluate the absorption and depuration capacity of this element in tilapia. The analyzes were performed using the inductively coupled plasma mass spectrometry technique (ICP-MS) in standard mode, and the accuracy of the method was confirmed by analyzes of the certified reference materials (NIST 1640a, SRM 1566a, DORM-3 and DOLT-4) which presented recoveries in the range of 80 to 110%. The concentrations of total arsenic determined in the tilapia exposed to As (III) and (V) by the bioaccumulation assays ranged from 0.06 - 8.79 μg g-1 in the livers, 0.05 - 0.78 μg g- 1 in the stomachs, 0.10 - 0.41 μg g-1 on the gills and 0.11 - 0.36 μg g-1 in the fillets, evidencing that the liver and stomach present the greatest capacities to absorb and accumulate the contaminant. A study of arsenic fractionation in fish and seafood tissues was also carried out to evaluate the distribution of arsenic in the lipid and protein phases, since there is a positive correlation between the accumulation of contaminants and the lipid content of the tissues. However, additional studies must be carried out to optimize the methodologies for lipid and protein extractions, since the tissues of the bioaccumulation assays presented low arsenic concentration and did not present the expected recoveries.
The fish market is expanding due to the search for healthier foods and because of the increase in the purchasing power of the population. However, despite the numerous health benefits, fish may be exposed to several inorganic contaminants, such as arsenic (As), which can trigger bioaccumulation processes in the aquatic species through the food chain. Thus, the determination of As in fish samples is of great analytical interest mainly due to its toxicity potential, since its effects are closely related to its chemical forms and their oxidation states, whereas the inorganic forms of As (III) and (V) are more toxic than organic forms. The aim of the present work was to develop and perform bioaccumulation assays with As (III) and (V) in Nile tilapia (Oreochromis niloticus) under laboratory conditions, in order to verify the distribution of As in tissues (liver, stomach, gills and fillet) and thus determine toxicokinetic parameters to evaluate the absorption and depuration capacity of this element in tilapia. The analyzes were performed using the inductively coupled plasma mass spectrometry technique (ICP-MS) in standard mode, and the accuracy of the method was confirmed by analyzes of the certified reference materials (NIST 1640a, SRM 1566a, DORM-3 and DOLT-4) which presented recoveries in the range of 80 to 110%. The concentrations of total arsenic determined in the tilapia exposed to As (III) and (V) by the bioaccumulation assays ranged from 0.06 - 8.79 μg g-1 in the livers, 0.05 - 0.78 μg g- 1 in the stomachs, 0.10 - 0.41 μg g-1 on the gills and 0.11 - 0.36 μg g-1 in the fillets, evidencing that the liver and stomach present the greatest capacities to absorb and accumulate the contaminant. A study of arsenic fractionation in fish and seafood tissues was also carried out to evaluate the distribution of arsenic in the lipid and protein phases, since there is a positive correlation between the accumulation of contaminants and the lipid content of the tissues. However, additional studies must be carried out to optimize the methodologies for lipid and protein extractions, since the tissues of the bioaccumulation assays presented low arsenic concentration and did not present the expected recoveries.
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Palavras-chave
Bioacumulação, Arsênio, Tilápia, Fracionamento, ICP-MS, Bioaccumulation, Arsenic, Fractionation