Long-term loss of color vision after exposure to mercury vapor

Abstract

We evaluated the color vision of 24 subjects (41.6 +/- 6.5 years; 6 females) who worked in fluorescent lamp industries. They had been occupationally exposed to mercury vapor (10.6 +/- 5.2 years) and had been away from the source of exposure for 6.4 +/- 4.04 years. Mean urinary concentration of mercury was 40.6 +/- 36.4 microg/g creatinine during or up to 1 year after exposure and 2.71 +/- 1.19 microg/g creatinine at the time of color vision testing or up to 1 year thereafter. All patients were diagnosed with chronic mercury intoxication, characterized by clinical symptoms and neuropsychological alterations. A control group (N = 36, 48.6 +/- 11.9 years, 10 females, 1.5 +/- 0.47 microg mercury/g creatinine) was subjected to the same tests. Inclusion criteria for both groups were Snellen VA 20/30 or better and absence of known ophthalmologic pathologies. Color discrimination was assessed with the Farnsworth D-15 test (D-15) and with the Lanthony D-15d test (D-15d). Significant differences were found between the two eyes of the patients (P < 0.001) in both tests. Results for the worst eye were also different from controls for both tests: P = 0.014 for D-15 and P < 0.001 for D-15d. As shown in previous studies, the D-15d proved to be more sensitive than the D-15 for the screening and diagnosis of the color discrimination losses. Since color discrimination losses were still present many years after the end of exposure, they may be considered to be irreversible, at least under the conditions of the present study.

Preliminary Findings on the Effects of Occupational Exposure to Mercury Vapor Below Safety Levels on Visual and Neuropsychological Functions

“…46,47 These findings agree with a previous study that showed subclinical losses of which the workers were unaware, 7 suggesting the D-15 d test would be useful for screening color vision deficiencies in cases of early neurotoxicity in exposed workers. In contrast with previous results in which the CCT was shown to be sensitive to evaluate a group several years after a long period of exposure to Hg vapor, 6 in the present group, differences between Hg-exposed subjects and controls were found for only two parameters in the Ellipse test.…”

“…[5][6][7][8][9][10] Nevertheless, there is no clear knowledge of the level of exposure at which Hg vapor causes adverse effects. Visual impairment has been found in subjects with very low urinary Hg concentration, such as children exposed to inorganic Hg in their living environment 11 and dentists exposed to inorganic Hg because of the manipulation of dental amalgam in their work environment.…”

Espaço de cores

“…No procedimento tradicional, as perdas dos grupos experimentais foram predominantes no eixo BY e, na reconstrução dos espaços de cores, as perdas se apresentaram em ambos os eixos, RG e BY, classifi cadas como difusas. Os resultados confi rmam os achados de perdas difusas na visão de cores de pacientes diabéticos tipo 2 sem retinopatia (Gualtieri, 2004;Santana et al, 2005;Ventura et al, 2003) e intoxicados por vapor de mercúrio (Feitosa-Santana, Costa, Lago, & Ventura, 2007;Silveira et al 2003;Silveira, Ventura, & Pinheiro, 2004;Ventura et al 2004;Ventura et al, 2005). Esse trabalho concluiu que os espaços de cores dos grupos de pacientes com diabetes mellitus tipo 2 sem retinopatia O estudo ainda sugere que a análise quantitativa da reconstrução dos espaços de cores, por ser uma medida objetiva da percepção do sujeito, pode ser efi ciente na distinção entre sujeitos com defi ciência e sujeitos normais.…”

Estudo eletrofisiológico e psicofísico em indivíduos intoxicados por vapor de mercúrio

“…Em indivíduos que vieram a óbito mais de dez anos depois de cessada a exposição ao vapor de mercúrio, foram encontrados depósitos de mercúrio no tecido cerebral em altas concentrações Kosta, Byrne, & Zelenko, 1975 Igata, 1993;Iwata & Abe, 1986 Barboni, Costa, Moura, Feitosa-Santana, Gualtieri, Lago, MedradoFaria, Silveira, & Ventura, 2007a;Costa, Tomaz, de Souza, Silveira, & Ventura, 2007b;Feitosa-Santana et al, 2007a;, assim como os sintomas patológicos gerais decorrentes da exposição ocupacional ao vapor de mercúrio group, 1993;Langworth, Almkvist, Soderman, & Wikstrom, 1992).…”

“…A capacidade de discriminação cromática também encontra-se reduzida na intoxicação por vapor de mercúrio Feitosa-Santana, 2005;Feitosa-Santana et al, 2007a;;…”