Long-term study on workers occupationally exposed to ethylbenzene

Ethylbenzene is synthesized from benzene; subject to catalytic dehydrogenation it yields styrene, a raw material for the production of synthetic rubber and plastics. Long-term biomonitoring of occupational ethylbenzene exposures, carried out in the past 20 years in some 200 ethylbenzene-production workers, revealed this substance to pose little hazard to human health. As it turned out, mandelic acid concentrations in these workers' urine never exceeded 3.25 mmol.l-1 and none of the exposed showed damage to hematopoiesis and/or liver tissue. Over the last 10 years no case of malignancy has been recorded in this industrial facility belonging to a larger chemical complex where the overall incidence of cancer is about 3 times the national average. Today's low-level ethylbenzene exposures would make it fully justifiable if the present-day MAC limits, both whole-shift (200 mg.m-3) and peak (1,000 mg.m-3), were to be halved, i.e. to be lowered to 100 mg.m3 and 500 mg.m3 respectively. These newly recommended limit values are no more exceeded nowadays.