BIOLOGICAL MONITORING OF CADMIUM EXPOSURE - RELIABILITY OF SPOT URINESAMPLES

Concentration-dilution of spot urine samples is a shortcoming of the b iological monitoring of industrial xenobiotics. To ascertain whether t he adjustment of urinary cadmium measured in spot samples is appropria te, urine samples were taken three times, once a week for 3 successive weeks, from 25 welders employed in the manufacture of jewellery (tota l 75 samples). Cadmium, creatinine, specific gravity, total urinary so lutes, urinary volume and urinary flow rate were measured in 12-h coll ections and in spot samples taken immediately afterwards. Creatinine a nd total urinary solutes showed high inverse correlation with urinary flow rate (r = -0.858 and r = -0.768 respectively). Urinary cadmium di splayed a similar trend but the correlation was not significant (r = - 0.145). Creatinine adjustment of urinary cadmium values in spot sample s increased the correlation with the same index in timed samples adjus ted for urinary volume (r = -0.808) or urinary flow rate (r = 0.821) c ompared with non-adjustment (r = 0.732 and r = 0.738, respectively). C reatinine adjustment of spot sample values is also suitable for a wide range of urinary concentrations; discarding excessively diluted or co ncentrated urines, correlation of urine samples improved for non-adjus ted or specific gravity-adjusted values, whereas no changes were obser ved for creatinine-adjusted values.