Control and hydrocarbon exposed workers participated in a cross-sectional study about the nephrotoxicity of chronic hydrocarbon exposure. Different markers of glomerular and tubular function as well as the celluria were examined and compared. The results show that the interaction between hypertension and hydrocarbon exposure has an influence on the kidney function. For the clearance the interaction age-exposure seems to play a more important role than age or exposure alone. The most useful markers appear to be the albuminuria, the N-acetyl-beta-D-glucosaminidase activity, the retinol-binding-protein concentration and the creatinine clearance.

The value of the glycosaminoglycans (GAG) determination in urine was examined in a population of hydrocarbon-exposed workers and compared to the usefulness of the fractional albumin clearance (FAC). Blood pressure and hydrocarbon exposure interact to increase the FAC but the GAG concentration seems less useful because too many other variables influence it as well.

In case-control studies on glomerulonephritis and organic solvents several authorshave assessed exposure to organic solvents with a score based on the self reported occupational history. The underlying principle is that all exposures can be weighted by an intensity factor and then added to get one number representative of lifetime exposure. As this score has hitherto not been validated the relation between this exposure score and kidney function tests in a population ofworkers with past or present exposure to organic solvents was examined. The results suggest that such relations do exist for the N-acetyl-fB-D-glucosaminidase (NAG) activity, erythrocyturia, and, perhaps, albuminuria but not for the protein creatinine ratio or for leucocyturia.In their case-control studies on glomerulonephritis and organic solvents Bell et al' and Ranskov et al2 assessed the exposure to organic solvents with an exposure score based on the occupational history. The relation between a quantitative exposure score and kidney function tests in a group of workers has not hitherto been examined.This was accomplished in the present study by comparing the possible relation between this exposure score and clinical kidney function tests in a group of workers with definable past or present exposure to organic solvents. As Bell's exposure score is a summary measure of the organic solvent exposure which supervenes in different jobs, our main purpose was its validation by the comparison of the kidney function tests in different exposure score groups and not between different occupational categories.Three hypotheses were examined: firstly, a search of correlation between exposure score and kidney function tests, secondly, the role of the duration of the exposure, and, finally, the possibility of a healthy worker effect. Subjects and methodsAltogether 148 workers were examined as a part of a larger epidemiological study programme on the nephrotoxicity of organic solvents. Seven could not be examined because ofholidays, leaving the job, refusal, foreign language, or organisational problems. The

The value of glycosaminoglycans determination in urine has been challenged because the relation between the glycosaminoglycans concentration and other signs of kidney damage is a matter of controversy. It is quite possible that the observed discrepancies could be due to the influence of the urine flow rate, the urine concentration and the time of day on the glycosaminoglycans concentration. Therefore, standardization of the urine sampling time and selection of the most appropriate unit to quantify glycosaminoglycans excretion seem to be essential.

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