title: Mercury toxicity in the Amazon: contrast sensitivity and color discrimination of subjects exposed to mercury.
abstract: 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.
authors.affiliation: Departamento de Fisiologia, Universidade Federal do Pará, 66055 Belém, Pará (PA), Brazil.
authors.forename: A R
authors.initials: AR
authors.lastname: Rodrigues
authors.forename: C R B
authors.initials: CR
authors.lastname: Souza
authors.forename: A M
authors.initials: AM
authors.lastname: Braga
authors.forename: P S S
authors.initials: PS
authors.lastname: Rodrigues
authors.forename: A T
authors.initials: AT
authors.lastname: Silveira
authors.forename: E T B
authors.initials: ET
authors.lastname: Damin
authors.forename: M I T
authors.initials: MI
authors.lastname: Côrtes
authors.forename: A J O
authors.initials: AJ
authors.lastname: Castro
authors.forename: G A
authors.initials: GA
authors.lastname: Mello
authors.forename: J L F
authors.initials: JL
authors.lastname: Vieira
authors.forename: M C N
authors.initials: MC
authors.lastname: Pinheiro
authors.forename: D F
authors.initials: DF
authors.lastname: Ventura
authors.forename: L C L
authors.initials: LC
authors.lastname: Silveira
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001938:Brazil; D016022:Case-Control Studies; D003118:Color Perception / Q000187:drug effects*; D003117:Color Vision Defects / Q000139:chemically induced* / Q000175:diagnosis; D015350:Contrast Sensitivity / Q000187:drug effects*; D004781:Environmental Exposure / Q000009:adverse effects; D004785:Environmental Pollutants; D006801:Humans; D008297:Male; D017056:Medical Laboratory Personnel; D008628:Mercury / Q000633:toxicity* / Q000652:urine; D008875:Middle Aged; D008906:Mining; D009784:Occupational Diseases / Q000139:chemically induced* / Q000175:diagnosis; D016273:Occupational Exposure / Q000009:adverse effects*; D013054:Spectrophotometry, Atomic; D013997:Time Factors
chemical_list: D004785:Environmental Pollutants; D008628:Mercury