Toxic health effects including reversible macrothrombocytosis in workers exposed to asphalt fumes

We investigated an outbreak of irritative and neurotoxic symptoms associated with exposure to asphalt fumes in a commercial lighting factory; 27 symptomatic female workers were clinically assessed including hematologic testing. When compared with a laboratory reference group (n = 107), the workers' mean platelet volume (MPV) was significantly higher and mean platelet count was lower (p = 0.013 and p = 0.048, respectively). Five months later, the factory's ventilation system was substantially modified. Follow‐up assessments 6 months postmodification on 15 of the original workers documented a significant decline in acute symptoms and a lowering of the subjects' mean MPV towards normal (p = 0.0007 by paired t‐test). The findings suggest that reversible macrothrombocytosis (enlarged platelets) can occur among symptomatic workers exposed to asphalt fumes. © 1994 Wiley‐Liss, Inc.