Stimulation of hydrogen peroxide production by drinking water contaminants in HL-60 cells sensitized by retinoic acid.

Chemical carcinogens, such as chloroform and trichloroethylene, are present in drinking water in Japan. As these contaminants are believed to have a role in carcinogenesis, we examined if chloroform and trichloroethylene, as well as methylene chloride, xylene, benzene, and ethanol, have the ability to generate hydrogen peroxide (H(2)O(2)) in human polymorphonuclear leukocytes (PMN) and human leukemia (HL-60) cells. Methylene chloride, benzene, xylene, trichloroethylene, and ethanol did not increase cellular H(2)O(2): production as measured by flow cytometry nor as observed by confocal laser microscopy. In PMN and RAuntreated HL-60 cells chloroform did not significantly affect H(2)O(2) levels. However, in HL-60 cells sensitized by pretreatment of 10 nM retinoic acid (RA) for 12 h, chloroform induced a significant increase in H(2)O(2), but the increase induced by trichloroethylene was not significant. The observed increase in fluorescence was confirmed using a confocal laser microscope. These results indicate that chloroform and trichloroethylene may stimulate H(2)O(2) production in HL60 cells sensitized by pretreatment of RA. Our method may be useful to test if weak stimulants can stimulate intracellular H(2)O(2) production.