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 µg/g creatinine during or up to 1 year after exposure and 2.71 ± 1.19 µg/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 µg 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 (D15d). 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.

Color‐space distortions following long‐term occupational exposure to mercury vapor

“…Considering the long-term of exposure to Hg in the present study, it is likely that the color vision losses reflect a cumulative exposure: the product of the duration and intensity of exposure. The hypothesis of a cumulative effect finds support in the fact that in all studies reporting an injurious effect of Hg on color vision, regardless of whether exposure was low-or highlevel, it was extended over years: 15.6 ± 3.3 years, range 5-18 ; 8.3 ± 5.5 years (Cavalleri et al, 1995); 9.6 ± 5.9 years (Cavalleri and Gobba, 1998); about 10 ± 5 years, range 4-25 (Feitosa-Santana et al, 2007; 14.7 ± 9.7 years, range 3-33 (Urban et al, 2003); 9.0 ± 4.7 years, range 3-22.5 ; 4.3 ± 2.8 years, range 1.5-9 (Barboni et al, 2009).…”

“…Mercury (Hg) is a potent neurotoxic agent, which can cause a range of nervous system impairments both in its elemental form (e.g. Cavalleri et al, 1995;Feitosa-Santana et al, 2007Urban et al, 2003;Ventura et al, 2004Ventura et al, , 2005 and as organic compounds such as methylmercury (e.g. Hunter and Russell, 1954;Lebel et al, 1996Lebel et al, , 1998Rodrigues et al, 2007;Silveira et al, 2003).…”

“…Barboni et al, 2009;da Costa et al, 2008;Gobba, 2000;Iregren et al, 2002;Lebel et al, 1996;Silveira et al, 2003). Color vision impairments due to Hg vapor exposure have been explored using color arrangement tests such as the D-15d test, indicating that error scores were significantly higher for the exposed groups and losses were predominantly along the tritan axis, showing impairment of the blue-yellow (BY) system (Cavalleri et al, 1995;Feitosa-Santana et al, 2007;Urban et al, 2003). However, recent findings showed that, along with the BY system, the red-green (RG) system is also affected, when color discrimination is assessed using the Cambridge Colour Test (CCT) Feitosa-Santana et al, 2008;Rodrigues et al, 2007;Silveira et al, 2003;Ventura et al, 2005).…”

Color Perception and Environmentally Based Impairments

“…Using the D-15d test, the degree and pattern of color vision loss were intensively investigated with regard to exposure to organic solvents, in particular toluene and styrene [2,[7][8][9][10], and to mercury [11]. The main finding across these studies is significant increase of the CCI in the occupationally exposed observers (compared to agematched controls).…”

Avaliação dos efeitos tóxicos do metilmercúrio na retina de duas espécies de teleósteos: Hoplias malabaricus e Danio rerio, utilizando um conjunto de biomarcadores biológicos

“…Em seus estudos demonstraram uma redução na sensibilidade espectral, sugerindo que ambos os mecanismos, escotópico e fotópico, são afetados pela exposição ao MeHg. Além disso, dados psicofísicos de humanos revelaram que a retina central deve ser afetada por intoxicações mercuriais, uma vez que várias funções mediadas por esta região mostraram perdas Feitosa-Santana et al, 2007;Zachi et al, 2007;Barboni et al, 2008).…”