Effect of petroleum derivatives and solvents on colour perception.
BACKGROUND
Occupational exposure to various neurotoxic chemicals has been shown to be associated with colour vision impairment. It seems that this can occur at low exposure levels, sometimes well below the recommended occupational threshold limits. This study was undertaken to determine the effect of exposure to petroleum derivatives (polyethylene, polystyrene) and solvents (perchloroethylene) on colour perception.


METHODS
Colour vision was assessed using the Ishihara plates, the D-15 test and the Farnsworth Munsell 100 Hue test. Two factories using petroleum derivatives and three dry cleaning premises were chosen at random. A total of 93 apparently healthy employees were recruited from the five workplaces. Two age-matched control groups comprising 56 people, who were support staff of the university with no exposure to petroleum, solvents or their derivatives, were also recruited.


RESULTS
All subjects passed the Ishihara test, showing that none had a congenital red-green defect. Some of the exposed employees failed the D-15 and had abnormally high FM100 Hue scores. All control subjects passed all the colour vision tests. The D-15 test showed that 28 per cent (26 of 93) of exposed employees had a colour vision defect whereas the FM 100 Hue test found that 63 per cent (59 of 93) had a colour vision defect. Most defects were of the blue-yellow type (22.6 per cent) when using the D-15 test. However, with the FM 100 Hue test, most defects were of the non-polar type with no specific axis (50.5 per cent). Mean total error scores calculated from the FM100 Hue test for exposed employees were statistically significantly higher than those of the control subjects.


CONCLUSIONS
Employees directly exposed to petroleum derivatives and solvents have a higher risk of acquiring colour vision defects compared to subjects who are not.
Sharanjeet-Kaur
Department of Optometry, Faculty of Allied Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia.
Mursyid
Ahmad
A
Kamaruddin
Afifah
A
Ariffin
Azrin
A
D000328:Adult; D016022:Case-Control Studies; D003118:Color Perception / Q000187:drug effects*; D003119:Color Perception Tests; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure; D020959:Polyethylene / Q000009:adverse effects*; D011137:Polystyrenes / Q000009:adverse effects*; D012997:Solvents / Q000009:adverse effects*; D013750:Tetrachloroethylene / Q000009:adverse effects*
D011137:Polystyrenes; D012997:Solvents; D020959:Polyethylene; D013750:Tetrachloroethylene