Assessment of colour vision impairment in male workers exposed to toluene generally above occupational exposure limits

Abstract

We investigated colour vision impairment in 45 male workers occupationally exposed to toluene (mean value of toluene concentration in ambient air = 119.96 ppm) and in 53 controls. Colour vision was evaluated by Lanthony-D-15 desaturated test and expressed as Age and Alcohol Intake Adjusted Colour Confusion Score (AACDS) or types of dyschromatopsia. Exposure was evaluated by measurement of toluene concentration in ambient air and blood, and hippuric acid and orthocresol determined in urine after the workshift. A statistically significant higher AACDS value was established in the exposed subjects compared to the controls (p < 0.0001). There was no significant difference between AACDS values on Wednesday morning compared to Monday morning. In the exposed group AACDS significantly correlated with the concentration of toluene in ambient air, concentration of toluene in blood and the concentration of hippuric acid in urine after the workshift (all p < 0.0001). Dyschromatopsias were detected in both groups, although no significant difference between groups was established. In the exposed group concentration of toluene in ambient air, alcohol intake and age explained 35.1%, concentration of toluene in blood, age and alcohol intake explained 19.9%, and concentration of hippuric acid in urine and age explained 19.2% of the variation in type III dyschromatopsia. Concentration of toluene in ambient air and age explained 28.3% of the variation in total dyschromatopsia, and concentration of hippuric acid and age explained 13.8%. In the control group, age and alcohol intake explained 19.6% of the variation in type III dyschromatopsia. In exposed workers a significant difference was found in the AACDS value compared to controls. However, no significant difference was found in the prevalence of colour vision loss in the yellow-blue and/or red-green axis. Based on the results of this study the authors conclude that the effect of toluene on colour vision can be chronic and that the possible reparation period in colour vision impairment is longer than 64 hours.

Does Occupational Exposure to Organic Solvents Affect Colour Discrimination?

“…Alcohol A study was conducted in 45 toluene-exposed workers in a consumption was in the range of 0-300 g/week for exposed printing press and in 53 non-exposed controls from a Croatian workers and 0-570 g/week for controls; the group mean values electrical product factory. [12] The two groups of workers were of were not significantly different. similar ages (mean age ~42 years) but the control subjects tended to consume more alcohol; median alcohol consumption in controls As in the previous study, blood toluene concentrations were was 87 g/week (range 0-790) compared with 34 g/week (range sampled before the work shift mid-week, but there was a discrep-0-262) in the toluene-exposed workers.…”

“…[3] tion above a threshold value (typically 500 g/week) were excluded from the analysis. Other studies [11][12][13] have tried to take account of 2. Styrene the effect of age and alcohol consumption by calculating an Age and Alcohol adjusted Colour Confusion Index (AACCI) using 2.1 Toxicokinetics and Toxicity regression analysis.…”

“…No change in colour discrimination during 30 min exposure to 290-360 ppm toluene Baelum et al [39] CS/acute, 43 print workers, Custom test Exposed printers made fewer test errors than controls LT 43 naive subjects In naive subjects colour discrimination deteriorated during 6.5h exposure to 100 ppm toluene, but no change in printers Baelum et al [40] Acute, LT 71 naive subjects Custom test No effects on colour discrimination of 7h exposure to 100 ppm toluene Cavalleri et al [41] CS 33 exposed rubber workers, D-15d Mean CCI significantly higher than in controls 16 controls CCI correlated with cumulative, but not contemporary, toluene exposure Campagna et CS 106 exposed print workers, D-15d Prevalence of test errors higher than in controls al. [42] 19 controls Test errors tritan and red-green Mean CCI significantly higher than in controls Zavalic et al [12] CS 45 exposed print workers, D-15d Not used in analysis 53 controls Zavalic et al [43,44] CS 32 exposed print workers, D-15d Not used in analysis 41 exposed shoemakers, 83 controls Nakatsuka et al [ week, so that only persistent effects due to past exposures were of toluene and colour discrimination. No airborne measurements detected and possible acute effects due to contemporary exposure of toluene were made in this study, but using a conversion based to toluene were specifically excluded.…”

Recent advances in occupational and environmental health hazards of workers exposed to gasoline compounds

“…Emerging evidence suggests that occupational exposure to organic solvents may be associated with impairment of visual function in many respects, and in particular color vision, including losses of blue yellow color, and secondary red green color dyschromatopsia [185][186][187].…”

Toluene inhalation exposure for 13 weeks causes persistent changes in electroretinograms of Long–Evans rats

“…Toluene is one of the most commonly used substances in industry and commerce and is also one of the organic solvents for which there have been reports of visual impairments in exposed workers, including impaired color discrimination (Campagna et al 2001, Cavalleri et al 2000, Zavalic et al 1998a, Zavalic et al 1998b, Zavalic et al 1998c) and decreased contrast sensitivity (Donoghue et al 1995). The U.S. Environmental Protection Agency evaluated the scientific literature regarding toluene exposure as a component of setting a reference concentration (RfC) value intended to be protective over a lifetime of exposure EPA ((EPA) 2005).…”