Banca de DEFESA: FÁBIO XIMENES DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : FÁBIO XIMENES DA SILVA
DATE: 31/03/2026
TIME: 08:30
LOCAL: Auditório PGDRA, Campus UNIR
TITLE:

DIETARY DETERMINANTS OF EXPOSURE TO METHYLMERCURY IN RIVERSIDE COMMUNITIES OF LOWER MADEIRA, RONDÔNIA

KEY WORDS:

mercury, human contamination, MeHg, human hair, Braszilian Amazon

PAGES: 73
BIG AREA: Ciências da Saúde
AREA: Saúde Coletiva
SUBÁREA: Saúde Pública
SUMMARY:

The issue of mercury (Hg) is globally recognized, but gaps persist that hinder effective mitigation strategies, especially in regions where fish is the main source of protein. In the Amazon, Indigenous and riverine populations are particularly vulnerable to methylmercury (MeHg) due to frequent fish consumption in contexts marked by a history of gold mining and recent socioenvironmental changes. This study aimed to assess adult exposure to Hg through fish consumption in four riverine communities of the Lower Madeira River (Demarcação, Calama, Nazaré, and São Carlos), and to estimate the dietary risk associated with consumption of different fish species. Between August and November 2022, hair samples were collected from 683 individuals (269 men, 414 women). Samples were processed in the laboratory by acid digestion and analyzed by cold vapor atomic absorption spectrophotometry, with strict analytical quality control. Sociodemographic information, eating habits, and fish consumption were obtained through structured surveys, and generalized linear mixed models were applied to identify predictors of total Hg concentration in hair (THg). The overall mean THg was 7.823 ± 8.175 mg kg⁻¹, with maximum values exceeding 70 mg kg⁻¹ and differences among communities, with Nazaré and Demarcação showing the highest mean levels. Men presented significantly higher concentrations than women in three of the four communities, and schooling showed an inverse relationship with THg. Exclusive fish consumption and preference for predatory, higher‑trophic‑level species were the main determinants of exposure. Age and length of residence also contributed to increased THg in some localities, indicating a cumulative long‑term effect. Based on Hg data in fish from the Madeira basin and the estimated mean weekly consumption (2.541 kg week⁻¹), the Estimated Weekly Intake (EWI), Hazard Quotient (HQ), and Maximum Safe Consuming Quantity (MSCQ) were calculated for 12 species. For almost all species, the EWI exceeded the Provisional Tolerable Weekly Intake (PTWI = 1.6 µg kg⁻¹ week⁻¹), and the HQ was greater than 1, indicating potential health risk. The MSCQ was extremely low for predatory species such as tucunaré, suggesting that the quantities currently ingested exceed by several orders of magnitude the levels considered safe. Comparison with historical data shows reduced exposure in some localities, but without a uniform trend among communities. In summary, Hg exposure in riverine communities of the Lower Madeira River remains high, with THg levels in hair above international safety reference values. The findings reinforce the need for integrated environmental health surveillance, risk communication, and promotion of dietary alternatives that reconcile the cultural and nutritional importance of fish with reduced mercury exposure.

 

 

COMMITTEE MEMBERS:
Presidente - 359961 - WANDERLEY RODRIGUES BASTOS
Interna - 1348799 - MARIANGELA SOARES DE AZEVEDO
Interno - 1905088 - RONALDO DE ALMEIDA
Interno - 1632974 - ANGELO GILBERTO MANZATTO
Interna - 2440330 - MONICA PEREIRA LIMA CUNHA
Externa ao Programa - 2388266 - NAYRA CARLA DE MELO - UNIRExterno à Instituição - MARCUCE ANTONIO MIRANDA DOS SANTOS - SMS