This study will examine the effect of a series of metals on the luciferase activity expression induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) in H1L6.1 cells. A 2-level factorial design was employed to identify major influential metal species of four test metals (As5+, Cr6+, Cd2+, and Pb2+) in the chemically activated luciferase expression (CALUX) of H1L6.1 cells. The observed data revealed that Cr6+ exerted a significant inhibiting effect on the luciferase activity. The impact of key metal species at various concentrations was analyzed for determination of the maximum tolerable level for H1L6.1 cell. It was observed that Cr6+ lowered the luciferase activity by 36.1 and 65.4%, at levels of 1.0 and 1.5 mu g-Cr/mL-medium (p < 0.05), respectively, but showed no significant difference at higher Cr6+ concentrations (2.0-5.0 mu g-Cr/mL-medium). (C) 2008 Elsevier B.V. All rights reserved.