Mercury toxicity in the Amazon: contrast sensitivity and color discrimination of subjects exposed to mercury

AUTOR(ES)

Rodrigues, A.R., Souza, C.R.B., Braga, A.M., Rodrigues, P.S.S., Silveira, A.T., Damin, E.T.B., Côrtes, M.I.T., Castro, A.J.O., Mello, G.A., Vieira, J.L.F., Pinheiro, M.C.N., Ventura, D.F., Silveira, L.C.L.

FONTE

Brazilian Journal of Medical and Biological Research

DATA DE PUBLICAÇÃO

2007-03

RESUMO

We measured visual performance in achromatic and chromatic spatial tasks of mercury-exposed subjects and compared the results with norms obtained from healthy individuals of similar age. Data were obtained for a group of 28 mercury-exposed subjects, comprising 20 Amazonian gold miners, 2 inhabitants of Amazonian riverside communities, and 6 laboratory technicians, who asked for medical care. Statistical norms were generated by testing healthy control subjects divided into three age groups. The performance of a substantial proportion of the mercury-exposed subjects was below the norms in all of these tasks. Eleven of 20 subjects (55%) performed below the norms in the achromatic contrast sensitivity task. The mercury-exposed subjects also had lower red-green contrast sensitivity deficits at all tested spatial frequencies (9/11 subjects; 81%). Three gold miners and 1 riverine (4/19 subjects, 21%) performed worse than normal subjects making more mistakes in the color arrangement test. Five of 10 subjects tested (50%), comprising 2 gold miners, 2 technicians, and 1 riverine, performed worse than normal in the color discrimination test, having areas of one or more MacAdam ellipse larger than normal subjects and high color discrimination thresholds at least in one color locus. These data indicate that psychophysical assessment can be used to quantify the degree of visual impairment of mercury-exposed subjects. They also suggest that some spatial tests such as the measurement of red-green chromatic contrast are sufficiently sensitive to detect visual dysfunction caused by mercury toxicity.

Documentos Relacionados

• Color, contrast sensitivity, and the cone mosaic.
• Lateral sensitivity modulation explains the flanker effect in contrast discrimination.
• Contrast sensitivity in diabetic subjects with and without retinopathy.
• Brightness discrimination and contrast sensitivity in chronic glaucoma--a clinical study.
• Normal pituitary hormone response to thyrotrophin and gonadotrophin releasing hormones in subjects exposed to elemental mercury vapour.