Critical levels of blood and urinary cadmium, urinary beta 2-microglobulin and retinol-binding protein for monitoring cadmium health effects.
The critical levels for monitoring cadmium health effects in 358 workers engaged in ore crushing/roasting (cadmium concentration in the workplace air 2.5-6.5 mg/m3), dry smelting (10.8-23.3 mg/m3), cadmium melting (0.01-0.16 mg/m3), and ingot making (2.8-4.7 mg/m3), were investigated. Exposure parameters such as blood and urinary cadmium were determined, together with biological parameters such as proteinuria, amino acids, glucose, beta 2-microglobulin, retinol-binding protein, albumin, plasma beta 2-microglobulin, creatinine clearance, tubular reabsorption of beta 2-microglobulin and phosphate, and blood and urinary levels of zinc, copper and lead. Factor analysis and stepwise regression analysis were then applied to the data to classify parameters and to find the main contributing parameter. Blood and urinary cadmium, urinary beta 2-microglobulin, retinol-binding protein and the ratio of urinary beta 2-microglobulin to albumin were also subjected to multiple correlation analysis, multiple regression analysis and the Chi-square test was applied to contingency tables. It is concluded, based on the data, that cadmium health effects may be assessed by using the following critical levels: blood cadmium: 10 micrograms/l, urinary cadmium: 10 micrograms/g creatinine; urinary beta 2-microglobulin: 2000 micrograms/g creatinine, urinary retinol-binding protein: 200 micrograms/g creatinine and a ratio of urinary beta 2-microglobulin to albumin of 0.001.