Researchers recognize the silent, negative and deleterious effects caused by mercury pollution in gold mining areas. Freshwater turtles are culturally part of the diet of riverside populations in the Amazon region and this area presents mercury (Hg) pollution issues mainly due to gold mining activities. Thus, this research aimed to evaluate the total mercury (THg) content in the different organs of Amazonian giant river turtle (Podocnemis expansa) and carry out a human health risk assessment associated with the consumption of these animals. This study was conducted in the Vila Balbina, municipality of Presidente Figueiredo, state of Amazonas, Brazil. Skin (n = 28), muscle (n = 19) and brain (n = 2) samples were analyzed by Atomic Absorption Spectrometry (TDA-AAS) and a DMA-80™ mercury analyzer was used for the total mercury determinations. The average values found for THg in the skin, muscle and brain samples were, respectively, 0.1045 mg·kg⁻¹, 0.1092 mg·kg⁻¹ and 0.0601 mg·kg⁻¹. Thus, THg was observed even though the P. expansa were kept in captivity, possibly due to previous contamination by air, water and food. The Hazard Quotient (HQ) was calculated considering a 9.07 g·day⁻¹ intake dose of P. expansa and the consumption of turtles once a week showed an HQ = 2.45, which may cause long-term injuries to human health. Although the muscle concentrations were below the maximum limit established by the World Health Organization (WHO) and Brazilian regulatory agencies, it is important to evaluate consumption factors such as amount ingested, frequency and animal gender, which may cause a potential risk to regular consumers due to mercury bioaccumulation. The WHO may consider various aspects in order to warn the Amazon population about the severity and silent hazard of this metal, especially due to the importance of this matrix in the region. This region urgently needs government actions to inhibit clandestine mining and to prevent future serious, chronic health problems of the entire population.

Birds of prey at higher trophic levels are particularly vulnerable to mercury pollution and can serve as indicators of trace elements in different ecosystems. Thus, the aim of this study was to evaluate the presence of mercury in feathers and livers in some birds of prey that occur in the State of Rio de Janeiro, Brazil. Eleven livers were collected from birds of pray during routine necropsies performed at the Rio de Janeiro Zoological Garden, and the feathers from animals in rehabilitation/release process. The results showed mercury concentrations ranged from 0.5 mg / kg to 1.3074 mg / kg in livers and from 0.3376 mg / kg to 3.000 mg / kg in feathers. Liver samples can be collected through invasive methods like biopsies, which involve anesthesia and handling of the bird, or during routine necropsies in zoological collections, breeding grounds, and from deceased birds found in the field, especially those affected by trampling or firearm injuries. Alternatively, analyzing feathers for mercury provides a practical, cost-effective, and non-invasive method that avoids risking harm to the bird's physical well-being.

Researchers are highly aware of the silent, negative effects caused by mercury pollution in gold mining areas. Freshwater turtles are culturally part of the diet of riverside populations in the Amazon region and this area presents mercury (Hg) pollution issues mainly due to gold mining activities. Thus, this research aimed to evaluate the total mercury (THg) content in the different organs of river turtles (P. expansa) and carry out a human health risk assessment associated with the consumption of these animals. Skin (n=28), muscle (n=19) and brain (n=2) samples were analyzed by Atomic Absorption Spectrometry (TDA-AAS) and a DMA-80™ mercury analyzer used for the total mercury determinations. The average values found for THg in the skin, muscle and brain samples were, respectively, 0.1045 mg.kg-1, 0.1092 mg.kg-1 and 0.0601mg.kg-1. Thus, THg was observed even though the P. expansa were kept in captivity, possibly due to previous contamination by air, water and food. The Hazard Quotient (HQ) was calculated considering a 9.07g.day-1 intake dose of P. expansa and the consumption of turtles once a week showed a HQ=2.45, which may cause long-term injuries to human health. Although the muscle concentrations were below the maximum limit established by the World Health Organization (WHO) and Brazilian regulatory agencies, it is important to evaluate consumption factors such as amount ingested, frequency and animal gender, which may cause a potential risk to regular consumers due to mercury bioaccumulation. The WHO may consider various aspects in order to warn the amazon population about the severity and silent hazard of this metal, especially due to the importance of this matrix in the region. This region urgently needs government actions to inhibit clandestine mining and to prevent future serious, chronic health problems of the entire population.

Guanabara Bay is Brazil’s second-largest bay and has a long history of intense industrial and domestic pollution. Some local communities rely on fish as a primary protein source, justifying an assessment of mercury (Hg) contamination. This study determined total mercury (THg) concentrations in nine fish species and evaluated the toxicological risks associated with human consumption. One hundred specimens were analyzed, and samples of muscle, liver, and gills were collected. THg analyses were performed using atomic absorption spectrometry following thermal decomposition, employing a DMA80 ^® analyzer. The liver showed the highest mean THg concentrations, followed by muscle and gills, reflecting its role in metal biotransformation. Predatory species exhibited higher levels, particularly Centropomus parallelus and Alosa fallax . One A. fallax individual exceeded the maximum permissible limit established by the Brazilian Health Regulatory Agency (ANVISA) (1.0 mg·kg⁻¹). Correlation analysis showed a significant positive association between liver and gill THg concentrations (ρ = 0.531; p < 0.0001), suggesting shared physiological mechanisms in Hg accumulation. A weak negative correlation was observed between body weight and muscle THg concentrations (ρ = − 0.242; *p* = 0.0153), whereas no significant association was found with fish length. These results suggest that body size alone did not explain the variability in muscle THg concentrations. Dietary habits and other ecological and physiological factors can also influence this. Risk assessment based on fish consumption data from 126 residents showed HQ < 1 across all scenarios, indicating low risk. However, the occurrence of a specimen exceeding the legal limit demonstrates the need for continued Hg monitoring in Guanabara Bay.