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. 2020 Jan 21:13:1428.
doi: 10.3389/fnins.2019.01428. eCollection 2019.

Comparison of Visual Functions of Two Amazonian Populations: Possible Consequences of Different Mercury Exposure

Eliza Maria da Costa Brito Lacerda  1 , Givago da Silva Souza  2   3 , Maria Izabel Tentes Cortes  4 , Anderson Raiol Rodrigues  2 , Maria Conceição Nascimento Pinheiro  2 , Luiz Carlos de Lima Silveira  2   3 , Dora Fix Ventura  5
Affiliations

Comparison of Visual Functions of Two Amazonian Populations: Possible Consequences of Different Mercury Exposure

Eliza Maria da Costa Brito Lacerda et al. Front Neurosci. .

Abstract

The present study investigated the visual perimetry and color vision of two Amazonian populations differently exposed to mercury. Ten riverines environmentally exposed to mercury by fish eating and 34 gold-miners occupationally exposed to mercury vapor. The visual perimetry was estimated using the Förster perimeter and the color vision was evaluated using a computerized version of Farnsworth-Munsell test. Riverine and gold-miners' hair mercury concentrations were quantified. Mercury hair concentration of the riverines was significantly higher than that from gold-miners. Riverines had lower perimetric area than the gold-miners. The errors in the hue ordering test of both Amazonian populations were larger than the controls (non-exposed subjects), but there was no difference between themselves. Riverines had significant multiple association between the visual function and hair mercury concentration, while the gold-miners has no significant association with the exposure. We concluded that the different ways of mercury exposure led to similar visual outcomes, with greater impairment in riverines (organic mercury exposed subjects).

Keywords: Amazon region; color vision; mercury vapor; neurotoxicology; organic mercury; psychophysics; visual field.

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Figures

FIGURE 1
FIGURE 1
Location of the mercury-exposed communities studied in the present investigation. Both communities shared similar geographical, economical, environmental conditions, but differed in mercury exposure.
FIGURE 2
FIGURE 2
Hair mercury concentration comparison between riverines and gold-miners. Riverines has significant higher hair mercury concentration than the gold-miners. ∗Significant difference, p < 0.05. Box-plots are composed by first (Q1), second (Q2), and third (Q3) quartiles, and whiskers represent the maximum (Max) and minimum (Min) values.
FIGURE 3
FIGURE 3
Visual perimetric results. (A) Visual perimetry of a standard observer (blue line) and of a mercury exposed observer (red line). (B) Visual perimetric area distribution of the riverine (green box-plot) and gold-miner (yellow box-plot) group. ∗Significant difference, p < 0.05. Box-plots are composed by first (Q1), second (Q2), and third (Q3) quartiles, and whiskers represent the maximum (Max) and minimum (Min) values.
FIGURE 4
FIGURE 4
Hue ordering results. Distribution of control (white box-plot), riverine (green box-plot), and gold-miner (yellow box-plot) groups. Both mercury exposed groups had higher error scores than the controls (∗p < 0.05). Box-plots are composed by first (Q1), second (Q2), and third (Q3) quartiles, and whiskers represent the maximum (Max) and minimum (Min) values.
FIGURE 5
FIGURE 5
Multiple regression between the visual outcomes (A, hue ordering test performance; B, visual perimetric area) and the independent variables (age and hair mercury concentration). Green circles represent the riverines data points (n = 5) and yellow circles represent gold-miners data points (n = 34). The grid represents the best three-dimensional model that fitted the visual outcomes to the independent variables.
See this image and copyright information in PMC

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