Study on kidney function in female workers exposed to perchlorethylene

Target Organ Metabolism, Toxicity, and Mechanisms of Trichloroethylene and Perchloroethylene: Key Similarities, Differences, and Data Gaps

Trichloroethylene (TCE) and perchloroethylene or tetrachloroethylene (PCE) are high-production volume chemicals with numerous industrial applications. As a consequence of their widespread use, these chemicals are ubiquitous environmental contaminants to which the general population is commonly exposed. It is widely assumed that TCE and PCE are toxicologically similar; both are simple olefins with three (TCE) or four (PCE) chlorines. Nonetheless, despite decades of research on the adverse health effects of TCE or PCE, few studies have directly compared these two toxicants. Although the metabolic pathways are qualitatively similar, quantitative differences in the flux and yield of metabolites exist. Recent human health assessments have uncovered some overlap in target organs that are affected by exposure to TCE or PCE, and divergent species- and sex-specificity with regard to cancer and noncancer hazards. The objective of this minireview is to highlight key similarities, differences, and data gaps in target organ metabolism and mechanism of toxicity. The main anticipated outcome of this review is to encourage research to 1) directly compare the responses to TCE and PCE using more sensitive biochemical techniques and robust statistical comparisons; 2) more closely examine interindividual variability in the relationship between toxicokinetics and toxicodynamics for TCE and PCE; 3) elucidate the effect of coexposure to these two toxicants; and 4) explore new mechanisms for target organ toxicity associated with TCE and/or PCE exposure.

Kidney and liver biomarkers in female dry-cleaning workers exposed to perchloroethylene

Blood and urine perchloroethylene and urine trichloroacetic acid, as markers of exposure, and serum AST, ALT, GGT and creatinine, urine total solutes and proteins, angiotensin converting enzyme, N-acetyl-ß-D-glucosaminidase and glutamine synthetase, as markers of effect, were measured in 40 dry-cleaning and 45 ironing-shop female workers. Average perchloroethylene air level in the dry-cleaning shops was 59.7 mg m(-3), i.e. three-fold lower than the current A.C.G.I.H. TLV-TWA (170 mg (m-3)). No statistically significant difference in the mean values of any of the effect markers was observed between the two groups, except for AST which was significantly higher in drycleaners. In addition, a statistically significant correlation was observed in dry-cleaners between environmental perchloroethylene and total urinary solutes (r = 0.308, p < 0.05) or urine glutamine synthetase (r= 0.469, p < 0 .01), between glutamine synthetase and blood perchloroethylene in post-shift (r= 0.406, p < 0.01) or urinary perchloroethylene in post(r= 0.571, p < 0.001) or pre-shift (r= 0.586, p < 0.001), and between urinary perchloroethylene in pre-shift and GGT (r= 0.407, p < 0.05). Interestingly, some statistically significant correlations between exposure and effect indices were found in ironing-shop workers alone, as in all subjects. Finally, transaminases, GGT and total urinary proteins were influenced by age and alcohol consumption which were significantly higher in dry-cleaners, thus providing an explanation for some of the correlations observed. In conclusion, our results show a dose-related increase of glutamine synthetase activity,a marker of damage of the pars recta of the kidney proximal tubule, in the urine of female subjects exposed to perchloroethylene concentrations in the work environment lower than current A.C.G.I.H. TLV-TWA.

Systematic literature review of uses and levels of occupational exposure to tetrachloroethylene

Tetrachloroethylene has been one of the most widely used chlorinated solvents in the United States. This review provides a basis for tetrachloroethylene exposure assessment in population-based case-control studies. We performed literature searches in MEDLINE, TOXLINE, NIOSHTIC, and the NIOSH Health Hazard Evaluation databases using relevant search terms. We calculated weighted arithmetic means from the measurement data and compiled these into three summary tables by type of operation: (1) dry cleaning, (2) degreasing, and (3) other operations. We identified 258 relevant documents, of which 179 (69%) contained useful descriptive information. Within the dry cleaning industry, the overall arithmetic mean (AM) for personal tetrachloroethylene exposures was 59 ppm (range: 0-4636, n = 1395). Machine operators who transferred wet garments to a dryer had the highest levels (AM = 150 ppm [range: 0-1000, n = 441]) of the jobs in this industry. The AM for personal measurements associated with degreasing was 95 ppm (range: 0-1800, n = 206). In addition, we identified several other sources of substantial tetrachloroethylene exposure, including cleaning mining equipment, testing coal, cleaning animal coats in taxidermy, and cleaning and duplicating film. Exposure assessment in population-based, case-control studies is a complex process requiring substantial resources. Researchers conducting these types of studies will be able to use results of the measurements to quantify tetrachloroethylene exposure levels for various jobs.

Potential health effects of occupational chlorinated solvent exposure

Based on toxicology, metabolism, animal studies, and human studies, occupational exposure to chlorinated aliphatic solvents (methanes, ethanes, and ethenes) has been associated with numerous adverse health effects, including central nervous system, reproductive, liver, and kidney toxicity, and carcinogenicity. However, many of these solvents remain in active, large-volume use. This article reviews the recent occupational epidemiology literature on the most widely used solvents, methylene chloride, chloroform, trichloroethylene, and tetrachloroethylene, and discusses other chlorinated aliphatics. The impact of studies to date has been lessened because of small study size, inability to control for confounding factors, particularly smoking and mixed occupational exposures, and the lack of evidence for a solid pathway from occupational exposure to biological evidence of exposure, to precursors of health effects, and to health effects. International differences in exposure limits may provide a "natural experiment" in the coming years if countries that have lowered exposure limits subsequently experience decreased adverse health effects among exposed workers. Such decreases could provide some evidence that higher levels of adverse health effects were associated with higher levels of solvent exposure. The definitive studies, which should be prospective biomarker studies incorporating body burden of solvents as well as markers of effect, remain to be done.

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.

ARF requiring hemodialysis after accidental perchloroethylene ingestion

Perchloroethylene (PCE) is an unsaturated chlorinated hydrocarbon in the form of a colorless, volatile liquid that is used as an industrial organic solvent for metal degreasing and for dry cleaning. The majority of cases of PCE intoxication have occurred by chronic inhalation, and PCE has been implicated previously in the development of mild renal dysfunction. However, the acute effects of PCE on the kidney are not well characterized, and the authors know of no reports of renal biopsy findings in the human. Here the case of a 32-year-old man who manifested by semicomatose state and oliguric acute renal failure requiring dialysis after accidental ingestion of 75 g of PCE is presented. A renal biopsy performed on the 19th day after ingestion showed features characteristic of severe acute tubular necrosis: aggregations of triangular or rhomboid crystals in the tubular lumens. A von Kossa stain showed that the crystal deposits were strongly positive for calcium. After 5 hemodialyses and conservative treatment, renal function gradually returned to normal.

Occupational exposure to tetrachloroethene and its effects on the kidneys

Occupational exposure to tetrachloroethene (TCE) has been reported to cause early adverse effects on the kidneys. We investigated the effects of TCE exposure on the kidneys in 82 exposed and 19 nonexposed workers from four dry-cleaning shops in The Netherlands. The mean inhaled amount of TCE in the exposed group, which was assessed by determination of its concentration in alveolar air samples, was 8.4 mg/m3 (range, 2.2-44.6 mg/m3). This value corresponds to a mean 8-hour time-weighted average exposure of 7.9 mg/m3 (range, 1-221 mg/m3). A chronic dose index (CDI) was estimated from data on the current TCE dose and the occupational history of the individual subjects. The mean CDI in the exposed group was 400 months X mg/m3 (range, 12-4882 months X mg/m3). Effects on the tubules were assessed with the parameters N-acetyl-beta-D-glucosaminidase, beta-galactosidase, alanine aminopeptidase, and retinol-binding protein (RBP) in urine. Early effects on the glomeruli were monitored with the parameter albumin in urine. Total protein in urine was determined for the general assessment of effects on the glomeruli and tubules. The tubular parameter RBP was increased in the exposed group, compared with the nonexposed group. None of the other parameters differed between the study groups, and none of the renal-effect parameters correlated with the TCE dose or the CDI. In conclusion, occupational exposure to TCE may cause a minor effect on the tubular RBP at exposure levels below the Dutch occupational exposure limit (240 mg/m3).

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.