Urinary excretion of proteins and enzymes in workers exposed to hydrocarbons in a shoe factory

Occupational exposure to toluene and its possible causative role in renal damage development in shoe workers

OBJECTIVES

An important, although, unprecise number of shoe workers in Leon, Mexico, are in continuous contact with toluene-based glues. The induction of renal glomerular and/or tubular lesions as a result of toluene exposure is still being discussed controversially. Our objective was to evaluate the extent of occupational exposure, assessing urinary o-Cresol excretion as a measure for toluene exposure in a population at risk as compared to a control population. Urinary albumin excretion (UAE) and N-acetyl-beta-D-glucosaminidase (NAG) enzymatic activity were tested to assess renal dysfunction.

METHODS

A cross-sectional study was performed comparing 50 toluene-exposed shoe workers and 25 control subjects. Urinary o-cresol was assessed on first and last day of labor week from exposed subjects. A single urine sample was obtained from control subjects. Urinary Albumin excretion (UAE) and (NAG) activity were examined in 12 h urine samples in all subjects. Urine and serum creatinine were measured to asses renal function.

RESULTS

At the end of the labor week, urinary o-cresol levels were higher in samples obtained from exposed subjects. Albumin excretion was similar in the exposed and control groups. NAG activity was greater in the exposed group compared to control group (median 3.5 U/g creatinine vs 1.9 U/g creatinine, z=2.6, P=0.009). An inverse relationship was found between schooling years and the NAG enzymatic activity for the two studied groups (r= -0.27, P=0.02),

CONCLUSIONS

Our findings support the hypothesis that toluene may be a factor associated with the presence of renal damage in exposed shoe workers. As NAG activity is increased, we believe the lesion initiates in the renal tubular cells.

Nephrotoxicity of organic solvents: biomarkers for early detection

OBJECTIVES

Evidence for a relationship between chronic kidney diseases or progression of already existing diseases (glomerulonephritides) and occupational solvent exposure has been found in case reports, in case-control studies and also in cross-sectional studies. An analysis of the available literature was performed with respect to markers measured in cross-sectional studies that might be useful for an early detection of solvent-induced effects on the kidney.

METHODS

The relevant cross-sectional studies were evaluated and the following markers were analyzed with respect to their suitability as biomarker for renal damage: total protein, albumin, transferrin, IgG, beta(2)-microglobulin, retinol-binding protein, N-acetyl-beta-D: -glucosaminidase, alanine aminopeptidase, beta-galactosidase, beta-glucuronidase, leucin aminopeptidase, alkaline phosphatase, lysozyme, Tamm-Horsfall protein and laminin fragments in urine as well as E-selectin, laminin and anti-laminin antibodies and anti-glomerular basement membrane antibodies in serum.

RESULTS

An increased albumin excretion was observed more frequently in groups of workers exposed to various solvents (like toluene, styrene, aliphatic/aromatic hydrocarbon mixtures, tetrachloroethene, mixtures of chlorinated hydrocarbons) than in controls. No clear pattern emerged for the other markers.

CONCLUSIONS

The determination of albumin excretion in the urine appears to be a useful parameter for monitoring solvent-exposed workers.

Occupational hydrocarbon exposure and chronic nephropathy

This review aims at discussing the questions raised by the hydrocarbon-related chronic nephropathy and its possible consequence, the hydrocarbon-related chronic renal failure. It has been attempted to adopt the point of view of the clinician. Therefore, the most important part of the review is devoted to a presentation and an analysis of the available data on humans. The main features of the available studies on human subjects are presented, their conclusions discussed in the light of the possible methodological flaws, and practical conclusions drawn. After a discussion of the main difficulties encountered for selecting the suitable exposure indicator, the studies are discussed in order of decreasing quality of the study design (cohort, case-control, cross-sectional studies, and the case reports). It is concluded that a great deal of controversies about chronic hydrocarbon-related nephropathy is explained by differences in the study design and that hydrocarbon-induced nephropathy is probably more than a mere hypothesis, although a causal relationship has not yet been proven. Finally, some practical consequences for dealing with a hydrocarbon-exposed patient diagnosed with a kidney disease and the need for further research are discussed.

Liver function tests and urinary albumin in house painters with previous heavy exposure to organic solvents

The serum activities or concentrations of aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), alkaline phosphatase (ALP), albumin, gamma-glutamyl transpeptidase (GGT), bilirubin (BIL), cholic acid (CHOL), chenodeoxycholic acid (CHENO), and transferrin with isoelectric point 5.7, and the urinary excretion of albumin were determined among male current or former house painters (n = 135) and house carpenters (n = 71) who had worked in their trades for at least 10 years before 1970. Workers who showed a value above the 90th percentile among the carpenters in at least one of the tests ASAT, ALAT, GGT, BIL, CHOL, or CHENO were regarded as showing "possible signs of liver dysfunction". Each participant's lifetime solvent exposure was evaluated by interview. The painters were divided into categories with low, intermediate, and heavy cumulative exposure during life (LTSE) or during the most exposed year (MEYSE). All participants stated none or slight recent exposure. The prevalence of possible signs of liver dysfunction increased with solvent exposure category according to LTSE as well as MEYSE with a numerically higher risk estimate in the heavy exposure category for MEYSE than for LTSE. ALP activity increased with exposure category according to both exposure estimates. This increase seemed to be due to an interaction between exposure to solvents and current or previous long term intake of medicines potentially toxic to the liver. None of these results was affected by whether or not the subjects had been exposed to solvents during the year before the investigation. The exposure to solvents was not significantly related to any other outcome variable. It is concluded that long term heavy exposure to solvents may elicit changes in conventional liver function tests indicative of a mild chronic effect on the liver. The findings also suggest that heavy solvent exposure during short time periods is a more likely cause of the findings than lifetime cumulative solvent exposure and that an interaction between solvent exposure and medicines potentially harmful to the liver may be important in the causation of the effects.