Bioaccumulation of As in tilapia (Oreochromis niloticus): fractionation of inorganic arsenic species

Author(s)

Nathalia dos Santos Ferreira

• Document type: Master's Dissertation
• Press: São José do Rio Preto. 2018-07-31.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências Letras e Ciências Exatas. São José do Rio Preto
• Defense date: 2018-06-26
• Advisor: Mario Henrique Gonzalez; Andrea Pinto Oliveira

Abstract

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. (AU)

• FAPESP's process: 16/05079-2 - Bioacumulation of As in tilápia (Oreochromis nilóticus): fractionation of as inorganic species
• Grantee: Nathalia dos Santos Ferreira
• Support Opportunities: Scholarships in Brazil - Master