Effectiveness of the biological monitoring of chemical exposure in the workplace: Results of a survey in an area of Northern Italy

A survey of biological monitoring results from 2000 to 2008 was carried out as a part of institutional activities performed by the Workplace Prevention and Safety Service (SPSAL) of the south area of Modena district (Italy). The survey involved 18 companies employing 945 workers altogether. According to workplace exposure, routine biological monitoring had been carried out yearly or 6-monthly in private laboratories chosen by each company. Analysis of consecutive data from six plants showed fluctuating biomarker levels inconsistent with expected occupational exposure and sometimes exceeding biological exposure indices. Surveillance samplings were thus organized for comparison to be carried out in a public reference laboratory. Overall results showed systematic underestimation of marker levels by the laboratories in charge of routine biomonitoring that, together with inappropriate biomarker selection and timing of sample collection, led to insufficient and/or ineffective corrective measures. These results raise major concerns on the reliability of laboratory assessments performed for the routine biomonitoring of exposed workers. Continuous surveillance of the consistency between biological and ambient monitoring data, together with the systematic evaluation of the analytical quality of laboratory results, would be essential for a reliable assessment of health risk in the workplace.