Urinary elimination of p-dichlorobenzene (p-DCB) and weighted exposure concentration

The aim of the present work is to determine p-DCB concentration in the urine of exposed workers and to verify a possible correlation with the environmental exposure. The authors studied four subjects exposed to different p-DCB environmental concentrations during a working week. The measurement of the substances was performed by means of a Hewlett-Packard 5880 A gas-chromatograph supplied with a Hewlett-Packard 5970 A Mass Selective Detector. The analysis was performed by a head space method (after determining the urine/air partition coefficient (lambda) by the multiple phase equilibration method). The lambda value (urine/air) of p-DCB is 10.8. The Authors found a significant relationship between the difference of p-DCB urinary concentration at the beginning and end of a daily work delta Cu (microgram/l) and the p-DCB environmental concentration C-I (mg/m3) (r = 0.64) (P less than 0.01); delta Cu = 0,48C-I + 15.61. We found that with an environmental exposure of 44.7 mg/m3 median value (geometrical deviation 1.15) there is an increase of p-DCB concentration in the urine of workers during the working week. For a daily environmental exposure of 450 mg/m3 (ACGIH TLV, 1984), we think that it is possible to propose a Biological Exposure Index (B.E.I.) of 250 micrograms/l as difference between beginning and end of a daily work.