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

Abstract

Color vision was examined in subjects with long-term occupational exposure to mercury (Hg) vapor. The color vision impairment was assessed by employing a quantitative measure of distortion of individual and group perceptual color spaces. Hg subjects (n = 18; 42.1 ± 6.5 years old; exposure time = 10.4 ± 5.0 years; time away from the exposure source = 6.8 ± 4.6 years) and controls (n = 18; 46.1 ± 8.4 years old) were examined using two arrangement tests, D-15 and D-15d, in the traditional way, and also in a triadic procedure. From each subject's 'odd-one-out' choices, matrices of inter-cap subjective dissimilarities were derived and processed by non-metric multidimensional scaling (MDS). D-15d results differed significantly between the Hg-group and the control group (p < 0.05), with the impairment predominantly along the tritan axis. 2D perceptual color spaces, individual and group, were reconstructed, with the dimensions interpreted as the red-green (RG) and the blue-yellow (BY) systems. When color configurations from the Hg-group were compared to those of the controls, they presented more fluctuations along both chromatic dimensions, indicating a statistically significant difference along the BY axis. In conclusion, the present findings confirm that color vision impairments persist in subjects that have received long-term occupational exposure to Hg-vapor although, at the time of testing, they were presenting mean urinary concentration within the normal range for non-exposed individuals. Considering the advantages of the triadic procedure in clinical evaluation of acquired color vision deficiencies, further studies should attempt to verify and/or improve its efficacy.

Saturation‐specific pattern of acquired colour vision deficiency in two clinical populations revealed by the method of triads

“…The MDS solutions for both clinical groups 14,15 revealed distributions significantly different from those in the respective control groups. The clinical groups' colour spaces tended to show a greater level of distortion and higher variability in the locations of stimuli along the B/ Y axis, that is possible tritan-type polar deficiency with a B/Y confusion axis.…”

“…10 This analysis of similarity data from the combined colour samples has revealed subtle differences, for example, between smoking and nonsmoking groups, 11 monozygotic and dizygotic twins, 12 between females and males 8 and between homozygous females and heterozygous carriers of colour vision deficiency. 13 For clinical populations, Feitosa-Santana et al elicited odd-one-out responses of this form-for randomised triads of a combined D-15 and D-15d stimulus set-for age-matched normal controls and groups whose colour vision had potentially been impaired by exposure to mercury vapor 14 or by diabetes mellitus type 2 (DM-2). 15 For convenience, although without losing generality or statistical power, the triads in these studies did not follow a predetermined list, but rather were generated randomly.…”

“…For clinical populations, Feitosa‐Santana et al elicited odd‐one‐out responses of this form—for randomised triads of a combined D‐15 and D‐15d stimulus set—for age‐matched normal controls and groups whose colour vision had potentially been impaired by exposure to mercury vapor or by diabetes mellitus type 2 (DM‐2) . For convenience, although without losing generality or statistical power, the triads in these studies did not follow a predetermined list, but rather were generated randomly.…”

“…In the geometrical paradigm, a polar deficiency is represented as a compression of colour space . Here, this was tested by reanalysing the data of Feitosa‐Santana et al within the framework of individual‐differences MDS. The latter imposes a single geometrical solution upon all the subjects, while allowing that solution to vary in a particular way (compression along a confusion axis) controlled by a small number of parameters, to fit it to each subject's responses.…”

Occupational styrene exposure and acquired dyschromatopsia: A systematic review and meta‐analysis

“…Moreover, they are potential manifestations of various pathological conditions, including diabetes mellitus, Parkinson's disease, and chronic alcoholism . By providing sensitive early markers, dyschromatopsia‐related findings may be useful for initiating treatment, as well as monitoring the progression of disease and injury …”