PILOT-STUDY OF PERIPHERAL MARKERS OF CATECHOLAMINERGIC SYSTEMS AMONG WORKERS OCCUPATIONALLY EXPOSED TO TOLUENE

In a pilot study, serum dopamine beta-hydroxylase (DBH), platelets mon oamine oxidase type B (MAO B) activities and basal plasma prolactin (P RL) were measured, among 10 workers occupationally exposed to toluene and 10 control subjects, preceeding and immediately following vacation . Six exposed subjects were employed in an adhesive tape making indust ry and 4 in a paint making industry. Their median basal levels of urin ary hippuric acid were 0.44 mmole/mmole creatinine (cr) (range 0.23-1. 97) and 0.18 mmole/mmole cr (range 0.15-0.19) respectively, the second to last morning of the work week, preceeding vacation. The level of b asal urinary hippuric acid among the control group was 0.26 mmole/mmol e cr (range 0.03-0.38). The workers from the adhesive tape plant repor ted a significantly higher number of symptoms experienced frequently ( Kruskal-Wallis, p<0.05). On a group basis, serum DBH was lowest among the workers from the adhesive tape plant, who had the highest levels o f basal urinary hippuric acid. In addition, a negative relation was ob served between hippuric acid and serum DBH, preceeding and following v acation (Rho=-0.46, p=0.05; Rho=-0.51, p=0.03). The observed changes i n serum DBH activity are consistent with its decrease in human, follow ing long-term exposure to styrene, another aromatic hydrocarbon. The f indings of this pilot study, on a limited number of individuals sugges t that DBH may be a sensitive peripheral bioindicator. Further studies of larger groups should be done to confirm the decrease in serum DBH activity with toluene exposure and explore whether this alteration is related to the neurotoxic impairments associated with exposure. (C) 19 96 Intox Press, Inc.