[Investigations on neurotoxicity of chemical substances at the workplace. III. Determination of the motor and sensory nerve conduction velocity in persons occupationally exposed to trichloroethylene]

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.

Occupational exposure to organic solvents and long-term nervous system damage detectable by brain imaging, neurophysiology or histopathology

The purpose of the present review is to assess the evidence published in scientific literature that industrial organic solvents as a generic group have the ability to induce long-term nervous system damage in workers that can be detected by techniques other than neuropsychological testing. The main body of evidence considered in this review was 40 studies involving the use of brain imaging, neurophysiological testing, gross autopsy or histopathology in groups of workers with long-term solvent exposure. Case reports involving both solvent abuse and occupational exposure, and experimental animal data have also been reviewed as supporting data. A number of the studies in groups of workers provide evidence of the presence of marginal atrophic abnormalities in the brain or deficits in nerve conduction velocity in solvent-exposed workers. However, there are limitations in the design of many of these studies, the strength of association between exposure and effect is not consistently strong, no dose-response relationship can be detected, the reported changes lack specificity and there is no coherence between the human and experimental animal data. Overall, it is not possible to draw reliable conclusions with respect to the presence or absence of nervous system damage related to the common properties of organic solvents.

Solvent-induced chronic toxic encephalopathy

Chlorinated solvents, especially trichloroethylene, have been extensively used for metal degreasing since the beginning of this century. There have been case reports of cranial nerve damage and symptoms of acute and reversible encephalopathy. However, another issue during the last decade is the possible existence of a syndrome of chronic cerebral dysfunction. Our study deals with the risk of developing a state of psychoorganic syndrome after long-term exposure to solvents, mainly trichloroethylene. In this historical cohort study, 96 metal degreasers participated in a clinical medical and psychological examination. The risk of developing psychoorganic syndrome was proportional to the exposure duration, to increasing age, and to decreasing primary intellectual level. Using logistic regression analysis, there was a significantly increased risk of developing psychoorganic syndrome from solvent exposure. There was an odds ratio of 5.6 (0.93-34.3) for psychoorganic syndrome in the medium-exposed group. In the most highly exposed group, with a mean full-time exposure duration of 11 years, there was a significantly increased risk of psychoorganic syndrome, the adjusted odds ratio was 11.2 (1.9-66.6). None of four other potential confounders (arteriosclerotic disease, neurologic/psychiatric disease, alcohol abuse, and current solvent exposure) had any significant associations to psychoorganic syndrome.

Acute neurotoxicity after trichloroethylene ingestion. Case report

Trichloroethylene (TCE), a solvent widely used in the chemical industry, in dry cleaning because of its degreasing action and as a household grease remover, is known to have a toxic action, especially on the nervous system. Cases of intoxication, acute and chronic, due to inhalation, are reported. We report a case, certainly an unusual one, of acute oral intoxication.