Metals bioaccumulation in fish captured from Araguari River upper section (Amazon biome), and risk assessment to human health resulting from their consumption

Background

The Araguari River is one of the most important rivers from Amapá State and its waters are essential as source of drinking water and food, especially for the traditional Amazonian populations. These populations have fish as their main protein source; however, studies have shown the metals bioaccumulation in fish caught in the Araguari River and the risks to human health resulting from fish consumption. Our objective was to investigate the bioaccumulation of Cd, Pb, Cr, Ni, Fe, Mn, Cu, Zn, and Hg in muscle tissue from the fish species Ageneiosus inermis and Hoplias aimara, and to evaluate the risks to human health resulting from their consumption.

Methods

Fish sampling was carried out between September and October 2018 at two sampling sites located in the Araguari River upper section. The metal concentrations quantification was performed by Atomic Absorption Spectrometry, except for Hg whose concentrations were determined using a hydride generator coupled to Inductively Coupled Plasma Optical Emission Spectrometry. For risk assessment of each metal individually we use the risk quotient (RQ) approach. To assess the risk of metal mixtures, present in fish muscle samples, we used the risk index (RI) approach. We also calculate the estimated daily intake (EDI).

Results

There was no statistical difference in the bioaccumulation of metals between both fish species. Only Cd and Pb presented average concentrations higher than the maximum limits established by Brazilian legislation aimed at protecting human health. The RI values obtained for both fish species were > 25, which indicates high risks to human health. The EDI values obtained for Hg in both fish species exceeded their reference dose (RfD). Taken together, our results show that these fish species are unfit for consumption.

Conclusions

Based on our results we recommend that the population does not consume the species A. inermis and H. aimara. When suspending consumption of both species is not possible, reducing their consumption is mandatory to reduce the exposure of human populations to toxic metals bioaccumulated in fish muscle tissue and thus reduce health risks.