The effect of selenium co-ingestion on mercury bioaccessibility in contaminated fish of the Amazon region

Mercury (Hg) is a toxic element that contaminates humans by consuming fish with high concentrations due to biomagnification in the food chain. This situation primarily impacts the riverside population in the Amazon region, as fish is their staple food. The interaction between selenium (Se) and Hg is well known due to their respective conceptual Pearson (soft-soft) characteristics. However, there needs to be more understanding of the impact of Se co-ingestion on Hg bioaccessibility. This scenario has prompted the investigation into the effects of consuming Se-rich food on the potential bioaccessibility of Hg when simultaneously ingesting contaminated fish. Cold vapor atomic absorption spectrometry (CV-AAS) measured Hg, and a hydride generator (HG-AAS) was used for Se. The results indicated that the piscivorous species Cichla sp. (Tucunaré fish) exhibited a Hg concentration over twice the limit established by the European Commission: 2.94 ± 0.21 μg g−1 for raw fish and 2.64 ± 0.16 μg g−1 for cooked fish. Concomitant ingestion of beans can reduce the potential bioaccessibility of Hg by 42% (68.4 to 25.8), and Brazil nuts co-ingestion can be reduced by 45% (68.4 to 23.1). However, due to the high fish consumption in the riverside population's diet, the Hazard Index (HI) and Target Hazard Quotient (THQ) values, including beans and Brazil nuts, exceeded the safe limit, even though THQ had decreased by 55%, and 66% with adding beans and Brazil nuts, respectively. These findings underscore the significant potential of Se in reducing Hg bioaccessibility through co-ingestion of foods containing this element. Additionally, it highlights the importance of considering regional dietary habits when assessing potential health risks. The results also sound like a warning about the food safety of the local communities.