Assessment of urban population exposure to trichloroethylene and tetrachloroethylene by means of biological monitoring

In vitro cytogenetic assessment of trichloroacetic acid in human peripheral blood lymphocytes

Trichloroacetic acid (TCA), a common water disinfection byproduct and a persistent metabolite of trichloroethylene (TCE), has been examined for its genotoxic potential in human lymphocytes. Chromosomal aberration (CA) and cytokinesis-block micronucleus (CBMN) assay were employed to assess the toxicity of TCA. Lymphocytes obtained from three healthy donors were exposed to 25, 50, and 100 μg/ml concentration of TCA separately. TCA exposure resulted in chromosomal anomalies and the formation of micronuclei in lymphocytes. Chromosome analysis revealed the dose-dependent and significant induction of CA. Chromatid break/chromosome break, fragments, and chromatid exchanges were commonly observed. Exposure of higher concentration (50 and 100 μg/ml) significantly inhibited mitotic index. Data obtained with CBMN assay indicated that the induction of micronucleus (MN) formation was greater than that of CA. At 25 μg/ml, TCA induced significant frequencies of MN as compared to control cells. Significant induction of MN at the lowest concentration indicates TCA may also interact with mitotic spindles. Lower percentage of CA and MN at 100 μg/ml as compared to 50 μg/ml indicates occurrence of severe cytotoxicity on exposure of 100 μg/ml TCA in lymphocytes. Collectively, results of both cytogenetic assays indicate that exposure of TCA can induce significant genotoxic and cytotoxic effects.

Organic contamination in dialysis water: trichloroethylene as a model compound

BACKGROUND

Routine water monitoring in a haemodialysis centre revealed high trichloroethylene (TCE) concentrations. The aim of this study is to describe the measures adopted after organic contamination of dialysis water in order to avoid the possibility of patient exposure. We also carried out in vitro experiments to evaluate the accumulation of TCE in various devices normally used in a dialysis water treatment system (DWTS).

METHODS

In vivo and in vitro blood and water TCE levels were determined by means of solid phase microextraction-gas chromatography/mass spectrometer.

RESULTS

High TCE concentrations were found throughout the DWTS; acceptably low levels were obtained only by replacing the activated charcoal, ionic-exchange resins, microfilters and PVC pipes. The adsorption and realising capacities of these devices were tested in vitro, and the elimination curves made it possible to calculate the total percentage of the previously absorbed TCE mass released into the water. Evidence of exposure was confirmed by the relatively high TCE levels in the patient blood samples taken 30 days after the last exposure even if the subjects were asymptomatic. In vivo experiments showed that the blood gain of TCE through the low flux membrane during the course of dialysis was about 77+/-10.4% of the amount carried by dialysis fluid as calculated on the basis of its partition coefficient value (K(b/w) 3.75).

CONCLUSIONS

This study shows that, when present in dialysis water, the lipophilic TCE contaminant can accumulate in various devices, thus transforming them into possible sources of exposure. This highlights the importance of periodically monitoring dialysis water for organic substances that have a great affinity to the blood compartment, in order to prevent occasional or chronic patient exposure.

Epidemiologic principles in the evaluation of suspected neurotoxic disorders

Epidemiology is the study of the patterns of disease and patterns of exposures in human populations. The main goals of epidemiology are to determine whether specific population groups have an increased risk of developing particular diseases and to determine what factors may be associated with increased risks of disease. In this article, the author focuses on epidemiologic studies of potential neurotoxic exposures, reviewing the basic principles involved and the special challenges associated with providing evidence of causal relationships between exposure and adverse health conditions.