OCCUPATIONAL AND ENVIRONMENTAL EXPOSURE OF GARAGE WORKERS AND TAXI DRIVERS TO AIRBORNE MANGANESE ARISING FROM THE USE OF METHYLCYCLOPENTADIENYL MANGANESE TRICARBONYL IN UNLEADED GASOLINE

Occupational and environmental exposure-to airborne manganese has been measured for two groups of workers in Montreal. taxi drivers and gara ge mechanics. In Canada methylcyclopentadienyl manganese tricarbonyl ( MMT) has replaced lead as an anti-knock agent in gasoline and represen ts a potentially important source of manganese contamination for the p opulation in general and for the two chosen groups of workers in parti cular. Twenty workers (10 taxi drivers and 10 garage mechanics) wore a personal air sampler for five consecutive working days and two off-wo rk periods. The amount of total Mn on each filter was determined by ne utron activation analysis and then converted to atmospheric Mn concent rations. The values obtained varied from 0.004 mug m-3 to 2.067 mug m- 3. At work the garage mechanics were exposed to an average of 0.250 mu g m-3 and the taxi drivers to 0.024 mug m-3. Off-work, the two groups were exposed respectively to an average of 0.007 mug m-3 and 0.011 mug m-3. In the garages there was twice as much Mn in the air on days whe n the doors were closed compared to days when they were left opened (0 .314 mug m-3/0.152 mug m-3). The levels found in this study remain wel l below the established limits for occupational and environmental airb orne exposure. These results will lead to further studies to positivel y identify the source of Mn as MMT and to explore other pathways leadi ng to the contamination of the general population.