Color vision impairment with low-level methylmercury exposure of an Amazonian population - Brazil

Author(s)

Feitosa-Santana, Claudia ^{[1, 2, 3, 4]} ; Souza, Givago da Silva ^[5] ; Pupo Sirius, Esaii Ventura ^[1] ; Rodrigues, Anderson Raiol ^[4] ; Tentes Cortes, Maria Izabel ^[6] ; de Lima Silveira, Luiz Carlos ^[5] ; Ventura, Dora Fix ^{[3, 4]}

Affiliation

^[1] Univ Fed ABC, Sao Paulo - Brazil

^[2] Hosp Israelita Albert Einstein, Sao Paulo - Brazil

^[3] Univ Sao Paulo, Inst Psicol, Dept Psicol Expt, Sao Paulo - Brazil

^[4] Univ Sao Paulo, Nucleo Neurociencias & Comportamento, Scio Paulo - Brazil

^[5] Univ Fed Para, Nucleo Med Trop, Belem, Para - Brazil

^[6] Univ Fed Amapa, Macapa - Brazil

• Document type: Journal article
• Source: NeuroToxicology; v. 66, p. 179-184, MAY 2018.
• Web of Science Citations: 2

Abstract

Land exploitation that follows deforestation and mining can result in soil erosion and the release of mercury to the waters of rivers in the Amazon Basin. Inorganic mercury is methylated by bacteria that are present in the environment and it serves as a source of human contamination through fish consumption in the form of methylmercury. Long-term exposure to low-level methylmercury in the riverside populations can lead to nervous system alterations, some of which are visual impairments such as loss of luminance contrast sensitivity, restricted visual fields and color vision defects. The present study sought to examine color vision in a group of adults living in the central Brazilian Amazon who were exposed to low-levels of methylmercury. Total Hg concentrations were measured from hair collected at the time of the testing. The D15d and FM100 color vision arrangement tests were applied in a population of 36 (22 males) and 42 (25 males), respectively. Controls were healthy volunteers from the cities of Sao Paulo for the D15d and Belem for the FM100. There was a statistically significant difference in performance between those who were exposed and controls for both tests (p < 0.01 and p < 0.0001, respectively, Mann-Whitney U test), meaning that adults living in this region of the Amazon made more mistakes on both tests when compared to controls. A linear regression was performed using Hg concentrations and test scores. Hg concentrations accounted for 7% and 2% of color D15d and FM100 arrangement test errors, respectively. Although other studies have previously found color vision impairment in the Amazon, they tested inhabitants on the east side of the Amazon, while this study was conducted in the central Amazon region and it is the first study in a population with no direct contact with the Hg source of contamination. These results suggest that long-term exposure to low-level methylmercury in riverside populations is more widely spread in the Amazon Basin than previously reported. This information is needed to implement public health policies that will ensure a safer environment for the Amazonian population. (C) 2018 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 08/58731-2 - Vision as a sensitive indicator of conditions threatening retinal and central nervous system function
• Grantee: Dora Selma Fix Ventura
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/26818-2 - Development and implementation of visual evaluation methods: clinical applications and animal models
• Grantee: Dora Selma Fix Ventura
• Support Opportunities: Research Projects - Thematic Grants