"TOXICITY ASSESSMENT OF CHEMICAL MIXTURE; COMBINATIONS OF CARBON TERTACHLORIDE, PHENOBARBITAL, CHLOFIBRATE IN VITRO"

Masato Naya¹, Hiroshi Takeda², Kikuo Yoshida¹, Junko Nakanishi ¹

¹National Institute of Advanced Industrial Science and Technology
²Mitsubishi Chemical Safety Institute Ltd. 

 EUROTOX (Amsterdam 2007/10/8)

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Abstract

Exposure to chemicals, in both the workplace and the environment generally, usually involves more than one chemical entity. Problems associated with multiple exposures have been discussed. Minimal data are available for risk assessment of possible interaction between chemicals during the evaluation of toxicity. In order to address this matter we studied the toxicity of chemical mixtures using in vitro rat primary hepatocytes culture system.
Hepatocyte suspensions were exposed to carbon tetrachloride (CT), phenobarbital (PB) or chlofibrate (CF) or the combinations of these three chemicals over a 24-hour incubation period. Lactate dehydrogenase (LDH), proteins, and gene expression in the hepatocytes after exposure to chemicals were determined. Gene expression in the hepatocytes were monitored by cDNA micro-array and real-time RT-PCR analysis.
In the case of CT + PB, CT + CF or PB + CF, there was no evidence in synergic effect in the LDH levels. Changes in protein folding-related genes and extra-cellular matrix-related genes were detectable in the CT treated cells. Changes in those related to transcription factor, immune response, coagulation reaction and glycogen synthesis were detectable in the PB treated cells. Changes in lipid metabolism-related genes were detectable in the CF treated cells. In the case of combination exposure, similar changes were observed with single treatment of each chemical. The cDNA micro-array analysis revealed differential gene expression profiles, and it may be based on the profiles to characterize the action of the chemicals. These data suggest that the cDNA micro-array is a useful technique for evaluation of possible toxicity of chemical mixture which was not detectable in the existing in vitro toxicity evaluation techniques.

Keywords

Toxicity, Assessment, Chemical mixture, Human health