Neurobehavioural effects on workers in a video tape manufacturing factory in Singapore

This study was carried out in a video tape manufacturing factory in Singapore where workers were exposed to mixed solvents consisting of methyl ethyl ketone (MEK), cyclohexanone (CHE), tetrahydrofuran (THF), and toluene (TOL). The objectives were to quantify workers' exposure to the various solvents and to evaluate if there were any neurobehavioural changes among the workers compared to controls. Nineteen exposed workers out of the workforce of forty-five were studied. Twenty-six workers (with no exposure) matched for ethnic group, age, and years of education served as controls. Eight-hour personal environmental samples were analyzed for the 19 workers along with symptom questionnaires, clinical examinations, and neurobehavioural tests including the Santa Ana Dexterity, Finger Tapping, Digit Span, and Visual Reproduction tests. The mean TWA concentrations for MEK, THF, CHE, and TOL were all below the current American Conference of Governmental Industrial Hygienists Threshold Limit Values (TLV). However, the total solvents concentration index exceed unity in one of the work areas. Significant differences were observed for prevalence of headache, and eyes and nose irritation among the exposed workers. There were also significant differences for the Santa Ana test for both-hands, Digit Span test and Visual Reproduction test. However, no dose-effect relation between behavioral scores and airborne solvent exposure was noted. The study suggests that solvent-exposed workers in video tape manufacturing plants may have poorer visual motor control and recent memory impairment (visual and verbal) than unexposed workers. Dermal absorption of solvents may have played a role in these results by increasing workers exposure.