1. Introduction

In contaminated environments, risk assessment and exposure to metals by fish consumption are concern issues, because it can become the main route of contaminants to humans. In general, studies focusing on the diagnosis of contaminant levels in fish are focused in the muscle tissue, the main edible part and the major target for metal storage [1–3]. However, little attention, especially in subtropical to tropical environments, has been paid to other tissues, which may provide other information of ecological interest. For instance, analysis of other organs can guarantee the safety of other predators, as bigger fishes and aquatic birds, which feed on the whole specimens.

Tissues as the liver, with highest lipid contents, can warn about recent metal accumulation, since metals can reach it very fast by bloodstream after absorption [4–6]. The literature has considered this organ as responsible for biological detoxification process, where part of the metal might be transferred to less sensitive tissues as the muscle [4, 7].

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it and with a free connection to the open sea [8]. Estuaries and mangrove ecosystems provide habitats for a large number of organisms and support very high productivity. They are also very densely populated and together with the coast represent about 60% of the world population [9]. It has been increasingly difficult to ignore the consequences of this occupation by industrial and urban activities on aquatic organisms, especially when it comes to disposal of potentially hazardous metals in sediments and water [10]. These dynamic ecosystems have some of the highest biotic diversities and biological production in the world, providing food and shelter to commercially important fish and shellfish species, including shelf species that spend some of their juvenile stages in estuaries [8].

The goal of this study is to characterize the levels of metal in muscle and liver tissues of four estuarine fish species (human-consumable protein) and associate it with different diet habits. Influences of these habits and the physical contaminated compartments on the uptake of metals and their distribution among the tissues are evaluated. The human health risk assessment of metals from fish food intake is also estimated.
