Elimination kinetics of metals after an accidental exposure to welding fumes

Objective We had the opportunity to study the kinetics of metals in blood and urine samples of a flame-sprayer exposed to high accident-prone workplace exposure. We measured over 1 year, the nickel, aluminium, and chromium concentrations in blood and urine specimens after exposure. On this basis, we evaluated the corresponding half-lives. Methods Blood and urine sampling were carried out five times after accidental exposure over a period of 1 year. The metals were analysed by graphite furnace atomic absorption spectrometry and Zeeman compensation with reliable methods. Either a mono-exponential or a bi-exponential function was fitted to the concentration-time courses of selected metals using weighted least squares non-linear regression analysis. The amount excreted in urine was calculated integrating the urinary decay curve and multiplying with the daily creatinine excretion. Results The first examination was carried out 15 days after exposure. The mean aluminium concentration in plasma was 8.2 mu g/l and in urine, 58.4 mu g/g creatinine. The mean nickel concentration in blood was 59.6 mu g/l and the excretion in urine 700 mu g/g creatinine. The mean chromium level in blood was 1.4 mu g/l in urine, 7.4 mu g/g creatinine. For the three elements, the metal concentrations in blood and urine exceeded the reference values at least in the initial phase. For nickel, the German biological threshold limit values (EKA) were exceeded. Conclusions Aluminium showed a mono-exponential decay, whereas the elimination of chromium and nickel was biphasic in biological fluids of the accidentally exposed welder. The half-lives were as follows: for aluminium 140 days (urine) and 160 days (plasma); for chromium 40 and 730 days (urine); for nickel 25 and 610 days (urine) as well as 30 and 240 days (blood). The renal clearance of aluminium and nickel was about 2 l/h estimated for the last monitoring day.