Urinary beryllium - a suitable tool for assessing occupational and environmental beryllium exposure?

Objectives: The reasons for the slow progress and lack of new knowledge in the biological monitoring of beryllium (Be) are to be found in the presumed small number of working activities involving exposure to the metal, and the lack of adequate analytical methods. The reference values for urinary Be reported earlier in the literature appear to be too high, due to the poor specificity and sensitivity of the adopted methods. The aim of this study was to correlate Be air concentrations and Be urinary levels to ascertain whether the biological indicator was suitable for assessing occupational exposure to the metal. Methods: To investigate the relationship between the Be concentrations in air and those excreted in urine, we examined 65 metallurgical workers exposed to very low levels of the metal, and 30 control subjects. The exposed workers were employed in two electric steel plants and two copper alloy foundries. The alloys were produced in electric furnaces, starting with scrap containing Be as an impurity. The Be concentrations in the air were monitored by area samplers and the levels of Be in the urine of the workers were determined in samples taken at the end of the shift. Both determinations were carried out by ICP-MS. Results: The median airborne Be concentrations in the copper alloy plants were 0.27 mug/m(3) in the furnace area and 0.31 mug/ m(3) in the casting area. Median values of 0.03 to 0.12 mug/ m(3) were determined in the steel plants, the relatively wide range probably due to differing amounts of Be in the scrap. Regression analysis was performed on the median values from four work areas and the corresponding urinary samples. A significant correlation was found for the relationship between external and internal exposure. The urinary Be levels were in the range between 0.12 and 0.15 mug/l with observation of the recommended TLV-TWA for inhalable dust of 0.2 mug/ m(3) (0.2 mug/l at the upper 95th percentile). Conclusions: Sufficient data are not currently available to be able to propose a BEI for urinary Be. Our results show that new investigations are necessary to improve the evaluation of dose indicators and the relationship between external and internal exposure to Be.