Biomonitoring of Bisphenol A exposed workers in a polyether production plant

Introduction:  Bisphenol A (BPA) is a chemical intermediate widely used in the production of synthetic polymers. While BPA shows a low acute and chronic toxicity, potential estrogenic effects of the compound are under scientific debate. Animal experiments have provided the basis for a widely accepted tolerable daily intake (TDI) value, but workplace studies are rare. As yet only a biological guidance value (BLW) for BPA based on the relation to the German Maximum Workplace Concentration (MAK value) has been set by the German Research Foundation (DFG).    

Methods:  In a study in BPA-handling employees of a polyether plant, spot urine samples were collected pre and post-shift. The urine specimens were analysed for free and total BPA, after enzymatic hydrolysis, using a validated and quality-controlled GC-MS method. To correct for diuretic variance, urinary creatinine was analysed by HPLC-UV. A reference group of employees from the same site but without occupational BPA exposure was also monitored.    

Results:  Conjugated BPA was detected after enzymatic hydrolysis in all pre and post-shift urines, while free BPA was traceable only in isolated cases. The median concentration of urinary BPA slightly increased during the shift, with most results being well in the range of the reference group and of the general population (about 10 microg/g creatinine). The maximum concentrations found in samples from BPA handling workers were about 500 microg/g creatinine or 2,100 microg/L, respectively (German BLW: 80,000 microg/L).    

Discussion:  All urinary BPA concentrations were far below the German Biological Guidance Value. Also, the recently proposed TDI-based so-called 'biomonitoring equivalent' of 2,600 microg/g creatinine was not exceeded. While an influence of different personal protective equipment on urinary BPA was observed, the overall low level of exposure does not suggest an increased health risk associated with occupational BPA exposure in the plant.