[Quality control in a system for the biological surveillance of exposure to n-hexane]

The paper reports the results of a quality assurance programme for routine biological monitoring of n-hexane exposure via measurement of its urinary metabolite 2.5-hexanedione. The programme involved a number of local occupational health services and was coordinated by the industrial toxicology laboratory in Florence. The analytical results show good agreement (68.6%, i.e., 46/67) between high urinary levels of 2.5-hexanedione (equal to or higher than an action level of 3.2 mg/l) and a relatively poor environmental situation at the workplace as reported by the local occupational health services. The fall in the number of 2.5-hexanedione values equal to or higher than the action level in the course of the study period (1990-1991) could be a result of the prevention measures taken. To confirm this hypothesis, 69 enterprises with at least 3 determinations in both 1990 and 1991 were selected. A 58% decrease in the mean 2.5-hexanedione value between 1990 and 1992 was observed in the group of enterprises (24) with at least one sentinel health event in 1990 (a value equal to or higher than 3.2 mg/l). In the group of enterprises with no sentinel health event in 1990, the mean 2.5-hexanedione values were practically unchanged. The authors stress the need for further studies to test the hypotheses based on the data obtained in this study.