Hematological toxicity of tetrachloroethylene in mice

Human health effects of tetrachloroethylene: key findings and scientific issues

BACKGROUND

The U.S. Environmental Protection Agency (EPA) completed a toxicological review of tetrachloroethylene (perchloroethylene, PCE) in February 2012 in support of the Integrated Risk Information System (IRIS).

OBJECTIVES

We reviewed key findings and scientific issues regarding the human health effects of PCE described in the U.S. EPA's Toxicological Review of Tetrachloroethylene (Perchloroethylene).

METHODS

The updated assessment of PCE synthesized and characterized a substantial database of epidemiological, experimental animal, and mechanistic studies. Key scientific issues were addressed through modeling of PCE toxicokinetics, synthesis of evidence from neurological studies, and analyses of toxicokinetic, mechanistic, and other factors (tumor latency, severity, and background rate) in interpreting experimental animal cancer findings. Considerations in evaluating epidemiological studies included the quality (e.g., specificity) of the exposure assessment methods and other essential design features, and the potential for alternative explanations for observed associations (e.g., bias or confounding).

DISCUSSION

Toxicokinetic modeling aided in characterizing the complex metabolism and multiple metabolites that contribute to PCE toxicity. The exposure assessment approach-a key evaluation factor for epidemiological studies of bladder cancer, non-Hodgkin lymphoma, and multiple myeloma-provided suggestive evidence of carcinogenicity. Bioassay data provided conclusive evidence of carcinogenicity in experimental animals. Neurotoxicity was identified as a sensitive noncancer health effect, occurring at low exposures: a conclusion supported by multiple studies. Evidence was integrated from human, experimental animal, and mechanistic data sets in assessing adverse health effects of PCE.

CONCLUSIONS

PCE is likely to be carcinogenic to humans. Neurotoxicity is a sensitive adverse health effect of PCE.

Trichloroethene and tetrachloroethene in ground waters of Zagreb, Croatia

At the end of 1986 the presence of chlorinated hydrocarbons was detected in the ground water of the industrial area of Zagreb, Croatia. Concentrations of trichloroethene and tetrachloroethene were close to or exceeded maximum admissible concentrations prescribed by the Public Health Regulations for drinking water (30 micrograms/l for trichloroethene and 10 micrograms/l for tetrachloroethene). The pumping-site situated within the area had been temporarily closed until a water-treatment plant based upon adsorption on activated carbon was built. Analysis of the results of adsorption of the investigated chlorinated hydrocarbons on activated carbon in granules confirmed a remarkably better adsorption of tetrachloroethene compared to trichloroethene. By constant monitoring and replacing of saturated carbon at the appropriate time, the concentrations of trichloroethene and tetrachloroethene in drinking water consumed by approx. 20% of the city population never exceeded maximum admissible concentrations in the course of 10 years.